Download Hi-Res Image 下载 Hi-Res 图像Download to MS-PowerPoint
下载到 MS-PowerPointCite This: 引用以下内容：ACS Nano ACS 纳米 2022, 16, 1, 111-118
下载到 MS-PowerPointCite This: 引用以下内容：ACS Nano ACS 纳米 2022, 16, 1, 111-118
Your access to this publication has been provided by Learn More
Article 文章2021 年 11 月 17 日
Exfoliation and Delamination of Ti3C2Tx MXene Prepared via Molten Salt Etching Route
通过熔盐蚀刻路线制备的 Ti 3 C 2 T x MXene 的剥离和分层Click to copy article link
点击复制文章链接Article link copied!
点击复制文章链接Article link copied!
- Liyuan Liu 刘丽媛Liyuan LiuCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceRS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, FranceMore by Liyuan Liu
- Metin Orbay 梅廷·奥尔贝Metin OrbayCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceRS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, FranceMore by Metin Orbay
- Sha Luo 沙罗Sha LuoCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceState Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, 730000 Lanzhou, Gansu, People’s Republic of ChinaMore by Sha Luo
- Sandrine Duluard 桑德琳·杜鲁阿德Sandrine DuluardCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceMore by Sandrine Duluard
- Hui Shao 邵慧Hui Shao 邵慧CIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, France
CIRIMAT， UMR CNRS 5085， Université Paul Sabatier 图卢兹第三大学， 118 Route de Narbonne， 31062 图卢兹， 法国RS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, France
RS2E，法国电化学储能网络，FR CNRS 3459,80039 Amiens Cedex，法国More by Hui Shao 更多 Hui Shao 的产品 - Justine Harmel 贾斯汀·哈梅尔Justine Harmel 贾斯汀·哈梅尔CIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, France
CIRIMAT， UMR CNRS 5085， Université Paul Sabatier 图卢兹第三大学， 118 Route de Narbonne， 31062 图卢兹， 法国RS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, France
RS2E，法国电化学储能网络，FR CNRS 3459,80039 Amiens Cedex，法国More by Justine Harmel 更多 Justine Harmel 的产品 - Patrick Rozier 帕特里克·罗齐尔Patrick RozierCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceRS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, FranceMore by Patrick Rozier
- Pierre-Louis Taberna 皮埃尔-路易·塔伯纳Pierre-Louis TabernaCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, FranceRS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, FranceMore by Pierre-Louis Taberna
- Patrice Simon* 帕特里斯·西蒙*Patrice Simon 帕特里斯·西蒙*E-mail: simon@chimie.ups-tlse.frCIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, France
CIRIMAT， UMR CNRS 5085， Université Paul Sabatier 图卢兹第三大学， 118 Route de Narbonne， 31062 图卢兹， 法国RS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, France
RS2E，法国电化学储能网络，FR CNRS 3459,80039 Amiens Cedex，法国
*电子邮件：simon@chimie.ups-tlse.frMore by Patrice Simon 更多 Patrice Simon 的产品
Abstract 抽象
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
MXenes are two-dimensional metal carbides or nitrides that are currently proposed in many applications thanks to their unique attributes including high conductivity and accessible surface. Recently, a synthetic route was proposed to prepare MXenes from the molten salt etching of precursors allowing for the preparation of MXene (denoted as MS-MXenes, for molten salt MXene) with tuned surface termination groups, resulting in improved electrochemical properties. However, further delamination of as-prepared multilayer MS-MXenes still remains a major challenge. Here, we report on the successful exfoliation of MS-Ti3C2Txvia the intercalation of the organic molecule TBAOH (tetrabutylammonium hydroxide), followed by sonication to separate the layers. The treatment time could be adapted to tune the wetting behavior of the MS-Ti3C2Tx. As a result, a self-supported Cl-terminated MXene film could be prepared by filtration. Finally, MS-Ti3C2Tx used as a Li-ion battery anode could achieve a high specific capacity of 225 mAh g–1 at a 1C rate together with an excellent rate capability of 95 mAh g–1 at 167C. These results also show that tuning of the surface chemistry of MXene is of key importance to this field with the likely result being increased electrochemical performance.
MXenes 是二维金属碳化物或氮化物，由于其独特的属性（包括高导电性和可接近的表面），目前在许多应用中被提出。最近，提出了一种合成路线，从前驱体的熔盐蚀刻中制备 MXenes，从而可以制备具有调谐表面终止基团的 MXene（表示为 MS-MXenes，用于熔盐 MXene），从而改善电化学性能。然而，制备的多层 MS-MXene 的进一步分层仍然是一个主要挑战。在这里，我们报告了通过嵌入有机分子 TBAOH（四丁基氢氧化铵）成功剥离 MS-Ti 3 C 2 T x ，然后超声处理以分离各层。可以调整处理时间以调整 MS-Ti 3 C 2 T x 的润湿行为。结果，可以通过过滤制备自支撑的 Cl 封端 MXene 薄膜。最后，用作锂离子电池负极的 MS-Ti 3 C 2 T x 可以在 1C 倍率下实现 225 mAh g –1 的高比容量，在 167C 下可以达到 95 mAh g –1 的优异倍率能力。这些结果还表明，调整 MXene 的表面化学性质对该领域至关重要，其结果可能是提高电化学性能。
This publication is licensed under the terms of your
institutional subscription.
Request reuse permissions.
本出版物根据您的机构订阅条款获得许可。请求重用权限。
Copyright © 2021 American Chemical Society
版权所有 © 2021 美国化学会
版权所有 © 2021 美国化学会
Introduction 介绍
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
The discovery of two-dimensional (2D) transition metal carbides or carbonitrides in 2011, termed MXenes, has attracted wide attention from the research community due to its great potential applications in various fields. (1−3) MXenes are conventionally prepared by selective etching in a F-containing aqueous electrolyte of atomically thin A layer elements from MAX phase precursors, where M stands for an early transition metal (Sc, Ti, V, Nb, Cr, etc.), A represents an element from group 13–16 (Al, Si, etc.), and X is carbon and/or nitrogen. (2) The general formula of MXenes is Mn+1XnTx (n = 1–3), where T denotes surface groups such as OH, O, and/or F groups. (1,4−6) The surface functional groups of MXenes affect not only the thermodynamic stability and optical properties but also the electronic (including band structure, work function) and electrochemical performance. (7) Although no method has been found so far to finely tune the types of surface functional groups, those surface terminations are highly dependent on the synthetic route and postsynthesis treatment. (8,9)
2011 年发现的二维 （2D） 过渡金属碳化物或碳氮化物，称为 MXenes，由于其在各个领域的巨大潜在应用而受到研究界的广泛关注。（1-3） MXenes 通常是通过在含 F 的水电解质中选择性蚀刻制备的，该电解质由来自 MAX 相前驱体的原子薄 A 层元素组成，其中 M 代表早期过渡金属（Sc、Ti、V、Nb、Cr 等），A 代表第 13-16 族的元素（Al、Si 等），X 是碳和/或氮。（2） MXenes 的一般分子式为 M n+1 X n T x （n = 1–3），其中 T 表示 OH、O 和/或 F 基团等表面基团。（1,4−6） MXenes 的表面官能团不仅影响热力学稳定性和光学性质，还影响电子（包括能带结构、功函数）和电化学性能。（7） 尽管到目前为止还没有找到微调表面官能团类型的方法，但这些表面终止高度依赖于合成路线和合成后处理。(8,9)
2011 年发现的二维 （2D） 过渡金属碳化物或碳氮化物，称为 MXenes，由于其在各个领域的巨大潜在应用而受到研究界的广泛关注。（1-3） MXenes 通常是通过在含 F 的水电解质中选择性蚀刻制备的，该电解质由来自 MAX 相前驱体的原子薄 A 层元素组成，其中 M 代表早期过渡金属（Sc、Ti、V、Nb、Cr 等），A 代表第 13-16 族的元素（Al、Si 等），X 是碳和/或氮。（2） MXenes 的一般分子式为 M n+1 X n T x （n = 1–3），其中 T 表示 OH、O 和/或 F 基团等表面基团。（1,4−6） MXenes 的表面官能团不仅影响热力学稳定性和光学性质，还影响电子（包括能带结构、功函数）和电化学性能。（7） 尽管到目前为止还没有找到微调表面官能团类型的方法，但这些表面终止高度依赖于合成路线和合成后处理。(8,9)
Until recently, aqueous solutions containing fluoride ions remained the mainstream method to etch the A-layer of the MAX phase to prepare MXenes. Etching electrolytes such as hydrofluoric acid (HF (2)) or fluoride-based compounds (LiF+HCl, (10) (NH4)HF2 (11)) are used, which results in −F, −OH, and −O surface-terminated MXene (hereinafter termed HF-MXene). All the etching mechanisms of the above methods involved the use/formation of a hazardous HF solution. It then appears particularly important to find alternative, nonhazardous synthesis routes to achieve scalable preparation of MXenes. Recently, Li etal. reported on the synthesis of the Zn-based MAX phase and surface F-free, Cl-terminated MXenes by reaction of the MAX phase and Lewis acidic molten salt at 550 °C via a replacement reaction mechanism. (12) Following this pioneering work, the synthesis of MS-MXenes was extended to a wide range of elements for the A-site of the MAX precursors (Zn, Al, Si, Ga) and Lewis acid melt composition. (13−15) The influence of the nature of the surface functional groups on the electrochemical performance of MS-MXene was also studied. (13) Used as a Li-ion battery anode, MS-Ti3C2Tx delivered a Li+ storage capacity up to 200 mAh g–1 in a 1 M LiPF6 carbonate-based electrolyte with good power performance (∼100 mAh g–1 at 60C). However, the rate performance was limited by the difficulty in exfoliating/delaminating further the prepared multilayered MS-MXene particles as a result of the change of synthesis route and surface groups.
直到最近，含有氟离子的水溶液仍然是刻蚀 MAX 相的 A 层以制备 MXenes 的主流方法。使用氢氟酸 （HF （2）） 或氟化物基化合物 （LiF+HCl， （10） （NH 4 ）HF 2 （11）） 等蚀刻电解质，得到 −F、−OH 和 −O 表面封端的 MXene（以下简称 HF-MXene）。上述方法的所有蚀刻机制都涉及有害 HF 溶液的使用/形成。因此，寻找替代的、无害的合成途径以实现 MXenes 的可扩展制备似乎尤为重要。最近，Li 等人。报道了 MAX 相和 Lewis 酸性熔盐在 550 °C 下通过置换反应机制反应合成 Zn 基 MAX 相和表面无 F、Cl 封端的 MXenes。（12） 在这项开创性工作之后，MS-MXenes 的合成扩展到 MAX 前驱体的 A 位元素（Zn、Al、Si、Ga）和路易斯酸熔融组成的广泛元素。（13−15） 还研究了表面官能团的性质对 MS-MXene 电化学性能的影响。（13） 用作锂离子电池负极，MS-Ti C T 在 1 M LiPF 6 碳酸酯基电解质中提供高达 200 mAh g –1 的锂 + 存储容量，具有良好的功率性能（60C 时 ∼100 mAh g –1 ）。 2 x 3 然而，由于合成路线和表面基团的变化，制备的多层 MS-MXene 颗粒难以进一步剥离/分层，因此倍率性能受到限制。
直到最近，含有氟离子的水溶液仍然是刻蚀 MAX 相的 A 层以制备 MXenes 的主流方法。使用氢氟酸 （HF （2）） 或氟化物基化合物 （LiF+HCl， （10） （NH 4 ）HF 2 （11）） 等蚀刻电解质，得到 −F、−OH 和 −O 表面封端的 MXene（以下简称 HF-MXene）。上述方法的所有蚀刻机制都涉及有害 HF 溶液的使用/形成。因此，寻找替代的、无害的合成途径以实现 MXenes 的可扩展制备似乎尤为重要。最近，Li 等人。报道了 MAX 相和 Lewis 酸性熔盐在 550 °C 下通过置换反应机制反应合成 Zn 基 MAX 相和表面无 F、Cl 封端的 MXenes。（12） 在这项开创性工作之后，MS-MXenes 的合成扩展到 MAX 前驱体的 A 位元素（Zn、Al、Si、Ga）和路易斯酸熔融组成的广泛元素。（13−15） 还研究了表面官能团的性质对 MS-MXene 电化学性能的影响。（13） 用作锂离子电池负极，MS-Ti C T 在 1 M LiPF 6 碳酸酯基电解质中提供高达 200 mAh g –1 的锂 + 存储容量，具有良好的功率性能（60C 时 ∼100 mAh g –1 ）。 2 x 3 然而，由于合成路线和表面基团的变化，制备的多层 MS-MXene 颗粒难以进一步剥离/分层，因此倍率性能受到限制。
Over the past few years, important research efforts have been made in HF-MXene delamination to improve their electrochemical performance compared to their multilayered counterparts. (16,17) Several organic molecules such as dimethyl sulfoxide (DMSO), (16) isopropylamine, (18) or tetrabutylammonium hydroxide (TBAOH) (19) have been reported as effective intercalants for efficient HF-MXenes delamination. (17)
在过去的几年里，HF-MXene 分层方面已经进行了重要的研究工作，以改善其与多层叠层相比的电化学性能。（16,17） 据报道，几种有机分子，如二甲基亚砜 （DMSO）、（16） 异丙胺、（18） 或四丁基氢氧化铵 （TBAOH） （19） 是高效 HF-MXenes 分层的有效嵌入剂。(17)
在过去的几年里，HF-MXene 分层方面已经进行了重要的研究工作，以改善其与多层叠层相比的电化学性能。（16,17） 据报道，几种有机分子，如二甲基亚砜 （DMSO）、（16） 异丙胺、（18） 或四丁基氢氧化铵 （TBAOH） （19） 是高效 HF-MXenes 分层的有效嵌入剂。(17)
In this work, we propose to further exfoliate MS-MXene by intercalation of the organic molecule tetrabutylammonium tetrafluoroborate (TBATFB), followed by sonication to separate the layers. The electrochemical behavior of MS-Ti3C2Tx used as a Li-ion battery anode before and after further exfoliation was compared, as well as the hydrophilic properties of the Ti3C2Tx/electrolyte interface. In addition, delaminated MS-Ti3C2Tx MXene could be successfully prepared by extending the surfactant treatment and sonification time in tetramethylammonium hydroxide (TMAOH).
在这项工作中，我们建议通过嵌入有机分子四氟硼酸四丁基铵 （TBATFB） 来进一步剥离 MS-MXene，然后超声处理以分离各层。比较了进一步剥离前后用作锂离子电池负极的 MS-Ti 3 C 2 T x 的电化学行为，以及 Ti 3 C 2 T x /电解质界面的亲水性能。此外，通过延长表面活性剂在四甲基氢氧化铵 （TMAOH） 中的处理和声化时间，可以成功制备分层的 MS-Ti 3 C 2 T x MXene。
在这项工作中，我们建议通过嵌入有机分子四氟硼酸四丁基铵 （TBATFB） 来进一步剥离 MS-MXene，然后超声处理以分离各层。比较了进一步剥离前后用作锂离子电池负极的 MS-Ti 3 C 2 T x 的电化学行为，以及 Ti 3 C 2 T x /电解质界面的亲水性能。此外，通过延长表面活性剂在四甲基氢氧化铵 （TMAOH） 中的处理和声化时间，可以成功制备分层的 MS-Ti 3 C 2 T x MXene。
Results and Discussion 结果与讨论
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
Materials Characterizations
材料表征
Figure 1a shows a sketch of the reaction between Ti3AlC2 and CuCl2 at 680 °C during Ti3C2 MXene synthesis; the reactions are listed below:
图 1a 显示了 Ti 3 3 C 2 MXene 合成过程中 Ti AlC 2 和 CuCl 2 在 680 °C 下的反应草图;反应如下：
CuCl2 together with NaCl/KCl turned to a molten state at the reaction temperature. The Al layer in Ti3AlC2 is oxidized into Al3+ by concomitant reduction of the Lewis acid Cu2+ into Cu on the MXene surface; further AlCl3 gas is formed, which can act as an effective agent to expand the MXene layer (eq 1). (12) Excess Cu2+ also partially reacts with the exposed Ti atoms from Ti3C2 to form metallic Cu, while charge compensation is ensured by Cl– anions reacting to form Ti3C2Cl2 (eq 2). (12) The formation mechanism of Ti3C2Cl2 from Ti3AlC2 is analogous to that of chemical etching of Ti3AlC2 in HF solution, where Cu2+ and Cl– act as H+ and F–, respectively. (2) As-prepared powders of Ti3C2Cl2 were further immersed in ammonium persulfate (APS) oxidizing solution to remove Cu particles from the Ti3C2Cl2 MXene surface, which also results in the addition of O-based surface groups. This final material prepared from this molten salt route will be noted as MS-Ti3C2Tx MXene, where Tx stands for O and Cl surface groups; under these experimental conditions, no −OH or −F surface termination is present on the MS-MXene surface. (13)
CuCl 2 与 NaCl/KCl 一起在反应温度下变为熔融态。Ti 3 AlC 2 中的 Al 层通过在 MXene 表面上将路易斯酸 Cu 还原 2+ 成 Cu 而被氧化成 3+ Al;进一步形成 AlCl 3 气体，它可以作为扩展 MXene 层的有效剂（方程 1）。（12） 过量的 Cu 2+ 也与 Ti 3 C 2 中暴露的 Ti 原子部分反应形成金属 Cu，而 Cl – 阴离子反应形成 Ti 3 C 2 Cl 2 （方程 2） 确保电荷补偿。（12） Ti 3 AlC 2 2 形成 Ti C 2 Cl 的机理类似于 Ti 3 AlC 2 在 HF 溶液中的化学蚀刻，其中 Cu 2+ 和 Cl 分别 – 充当 H + 和 F – 。 3 （2） 将制备的 Ti 3 C 2 Cl 粉末进一步浸入过硫酸铵 （APS） 氧化液中，以去除 Ti 3 C 2 Cl 2 MXene 表面的 Cu 颗粒，这也导致了 O 基表面基团的添加。 2 由该熔盐路线制备的最终材料将记为 MS-Ti 3 C 2 T x MXene，其中 T x 代表 O 和 Cl 表面基团;在这些实验条件下，MS-MXene 表面不存在 -OH 或 -F 表面终止。(13)
图 1a 显示了 Ti 3 3 C 2 MXene 合成过程中 Ti AlC 2 和 CuCl 2 在 680 °C 下的反应草图;反应如下：
(1)
(2)
CuCl 2 与 NaCl/KCl 一起在反应温度下变为熔融态。Ti 3 AlC 2 中的 Al 层通过在 MXene 表面上将路易斯酸 Cu 还原 2+ 成 Cu 而被氧化成 3+ Al;进一步形成 AlCl 3 气体，它可以作为扩展 MXene 层的有效剂（方程 1）。（12） 过量的 Cu 2+ 也与 Ti 3 C 2 中暴露的 Ti 原子部分反应形成金属 Cu，而 Cl – 阴离子反应形成 Ti 3 C 2 Cl 2 （方程 2） 确保电荷补偿。（12） Ti 3 AlC 2 2 形成 Ti C 2 Cl 的机理类似于 Ti 3 AlC 2 在 HF 溶液中的化学蚀刻，其中 Cu 2+ 和 Cl 分别 – 充当 H + 和 F – 。 3 （2） 将制备的 Ti 3 C 2 Cl 粉末进一步浸入过硫酸铵 （APS） 氧化液中，以去除 Ti 3 C 2 Cl 2 MXene 表面的 Cu 颗粒，这也导致了 O 基表面基团的添加。 2 由该熔盐路线制备的最终材料将记为 MS-Ti 3 C 2 T x MXene，其中 T x 代表 O 和 Cl 表面基团;在这些实验条件下，MS-MXene 表面不存在 -OH 或 -F 表面终止。(13)
Figure 1 图 1
Figure 1. Schematic and realistic views of the molten salt synthesis method and exfoliation process. (a) Schematic representation of the synthesis and exfoliation of MXene prepared via a Lewis acidic etching route. Pristine MS-Ti3C2Tx before (left) and after (right) TBAOH treatment after (b) centrifugation at 3500 rpm for 30 min and (c) collection by filtration. (d) Tyndall effect for nanoflakes dispersed in water after TBAOH treatment.
图 1.熔盐合成方法和剥离过程的示意图和实景图。（a） 通过 Lewis 酸性蚀刻路线制备的 MXene 合成和剥离的示意图。（b） 以 3500 rpm 离心 30 分钟和 （c） 过滤收集后，TBAOH 处理前（左）和后（右）的原始 MS-Ti 3 C 2 T x 。（d） TBAOH 处理后分散在水中的纳米薄片的 Tyndall 效应。
For conventional HF-MXenes, one of the most widely applied methods for delamination is to intercalate DMSO solvent followed by sonication, (17) thanks to matching the surface energy between DMSO and HF-MXene; however, this method failed to produce delaminated MS-Ti3C2Tx. As shown in Figure S1, the SEM image of DMSO-treated MS-Ti3C2Tx shows thick, multilayer MS-MXene flakes, and precipitation in the solution is observed after just a couple of hours. After APS washing, the pH of MS-Ti3C2Tx in deionized water is 3.9, indicating the release of protons from MS-Ti3C2Tx MXene in the electrolyte. In addition, a small number of K-ions coming from the MS precursor still remain on the MXene surface (see Table S1). After the addition of TBAOH into the MS-Ti3C2Tx suspension, the pH gradient between the acidic MS-MXene and alkaline TBAOH electrolyte results in ion exchange between the bulky tetraalkylammonium ions (TBA+) and cations (protons and K-ions), leading to MXene structure swelling. After sonication to promote exfoliation, TBAOH-treated MS-Ti3C2Tx was centrifuged at 3500 rpm for 30 min to eliminate the sediment. Figure 1b shows the pristine and TBAOH-treated MS-Ti3C2Tx after centrifugation followed by sonication. For pristine MS-Ti3C2Tx, the precipitation occurs after only 2 h, while the suspension of TBAOH-treated MS-MXene is still stable after 2 weeks (see Figure S2). By shining a laser beam into the suspension of TBAOH-treated MS-MXene, a clear Tyndall effect can be observed, as shown in Figure 1d, thereby confirming the existence of a colloidal suspension. (18) Differently from pristine MS-MXene, the TBAOH-treated MS-MXene material can form a film after filtration, as shown in Figure 1c; however, the film is brittle with poor mechanical properties, differently from HF-MXene after delamination. (10) MS-Ti3C2Tx has also been treated with 1 M NaOH and tetraethylammonium hydroxide (TEAOH) by following the same procedure, but no stable suspension could be obtained (Figure S3). A large TBA+ cation results in improving the stability of the suspension, assumed to be linked with a decrease in the flake thickness and improved exfoliation of the MS-MXene.
对于传统的 HF-MXene，应用最广泛的分层方法之一是嵌入 DMSO 溶剂，然后进行超声处理，（17） 这要归功于 DMSO 和 HF-MXene 之间的表面能匹配;然而，这种方法未能产生分层的 MS-Ti 3 C 2 T x 。如图 S1 所示，DMSO 处理的 MS-Ti 3 C 2 T x 的 SEM 图像显示厚厚的多层 MS-MXene 薄片，并且仅在几个小时后即可观察到溶液中的沉淀。APS 洗涤后，去离子水中 MS-Ti 3 C 2 T x 的 pH 值为 3.9，表明电解液中 MS-Ti 3 C 2 T x MXene 释放了质子。此外，来自 MS 前驱体的少量 K 离子仍保留在 MXene 表面上（参见表 S1）。在 MS-Ti 3 C 2 T x 悬浮液中添加 TBAOH 后，酸性 MS-MXene 和碱性 TBAOH 电解质之间的 pH 梯度导致大体积四烷基铵离子 （TBA + ） 和阳离子（质子和 K 离子）之间的离子交换，导致 MXene 结构膨胀。超声处理以促进剥离后，将 TBAOH 处理的 MS-Ti 3 C 2 T x 以 3500 rpm 离心 30 分钟以去除沉淀物。图 1b 显示了离心后超声处理后的原始和 TBAOH 处理的 MS-Ti 3 C 2 T x 。对于原始 MS-Ti 3 C 2 T x ，沉淀仅在 2 小时后发生，而 TBAOH 处理的 MS-MXene 的悬浮液在 2 周后仍然稳定（参见图 S2）。 通过将激光束照射到 TBAOH 处理的 MS-MXene 的悬浮液中，可以观察到明显的 Tyndall 效应，如图 1d 所示，从而确认胶体悬浮液的存在。（18） 与原始的 MS-MXene 不同，TBAOH 处理的 MS-MXene 材料在过滤后可以形成薄膜，如图 1c 所示;然而，该薄膜较脆，机械性能差，与分层后的 HF-MXene 不同。（10） MS-Ti 3 C 2 T x 也按照相同的程序用 1 M NaOH 和四乙基氢氧化铵 （TEAOH） 处理，但无法获得稳定的悬浮液（图 S3）。大的 TBA + 阳离子导致悬浮液的稳定性提高，据推测与薄片厚度的减少和 MS-MXene 的剥离改善有关。
对于传统的 HF-MXene，应用最广泛的分层方法之一是嵌入 DMSO 溶剂，然后进行超声处理，（17） 这要归功于 DMSO 和 HF-MXene 之间的表面能匹配;然而，这种方法未能产生分层的 MS-Ti 3 C 2 T x 。如图 S1 所示，DMSO 处理的 MS-Ti 3 C 2 T x 的 SEM 图像显示厚厚的多层 MS-MXene 薄片，并且仅在几个小时后即可观察到溶液中的沉淀。APS 洗涤后，去离子水中 MS-Ti 3 C 2 T x 的 pH 值为 3.9，表明电解液中 MS-Ti 3 C 2 T x MXene 释放了质子。此外，来自 MS 前驱体的少量 K 离子仍保留在 MXene 表面上（参见表 S1）。在 MS-Ti 3 C 2 T x 悬浮液中添加 TBAOH 后，酸性 MS-MXene 和碱性 TBAOH 电解质之间的 pH 梯度导致大体积四烷基铵离子 （TBA + ） 和阳离子（质子和 K 离子）之间的离子交换，导致 MXene 结构膨胀。超声处理以促进剥离后，将 TBAOH 处理的 MS-Ti 3 C 2 T x 以 3500 rpm 离心 30 分钟以去除沉淀物。图 1b 显示了离心后超声处理后的原始和 TBAOH 处理的 MS-Ti 3 C 2 T x 。对于原始 MS-Ti 3 C 2 T x ，沉淀仅在 2 小时后发生，而 TBAOH 处理的 MS-MXene 的悬浮液在 2 周后仍然稳定（参见图 S2）。 通过将激光束照射到 TBAOH 处理的 MS-MXene 的悬浮液中，可以观察到明显的 Tyndall 效应，如图 1d 所示，从而确认胶体悬浮液的存在。（18） 与原始的 MS-MXene 不同，TBAOH 处理的 MS-MXene 材料在过滤后可以形成薄膜，如图 1c 所示;然而，该薄膜较脆，机械性能差，与分层后的 HF-MXene 不同。（10） MS-Ti 3 C 2 T x 也按照相同的程序用 1 M NaOH 和四乙基氢氧化铵 （TEAOH） 处理，但无法获得稳定的悬浮液（图 S3）。大的 TBA + 阳离子导致悬浮液的稳定性提高，据推测与薄片厚度的减少和 MS-MXene 的剥离改善有关。
Figure 2a shows the X-ray diffraction (XRD) patterns of the MAX phase precursor (black plot), the MXene after removal from the molten salt bath (red plot) and after washing in APS to remove Cu (blue plot), and the MXene after TBAOH exfoliation treatment (green). Right after synthesis (Figure 2a, red plot), most of the diffraction peaks corresponding to the pristine Ti3AlC2MAX precursor disappeared, leaving (00l) peaks as well as several broad and low-intensity peaks in the 2θ range from 5° to 80°. These features indicate the successful etching of the Al layer from Ti3AlC2 into layered Ti3C2. Additionally, the shift of Ti3C2 (002) diffraction peaks from 2θ = 9.63° to 8.07° (±0.02°) indicates an expansion of the interlayer distance from 9.17 Å to 10.98 Å (±0.03 Å). The newly formed sharp and intense peaks centered at 2θ angles of 43.29°, 50.43°, and 74.13° can be identified as metallic Cu. The XRD pattern after washing with APS ((NH4)2S2O8) solution only shows (001) peaks (Figure 2a, blue plot) as a result of Cu removal. After TBAOH treatment and freeze-drying, the main peaks of MS-Ti3C2Tx in the XRD pattern (Figure 2a, green plot) still remain, which evidence Ti3C2Tx. The low intensity of (002) and (004) peaks reveals that freeze-dried TBAOH-treated MS-MXene flakes sit in a different orientation. In addition, both (002) and (004) peaks slightly shift from 8.07° to 7.81° and 16.14° to 15.62°, respectively, for (002) and (004) peaks. This indicates a slight expansion of the MS-MXene structure following intercalation of the TBA cation, from 10.94 Å (neat) to 11.31 Å (after TBAOH treatment). At the same time, slight peak broadening is observed, indicating a smaller flake size. (20) Differently from the accordion-like multilayered morphology of original MS-Ti3C2Tx (Figure 2b), a parallel restacked layered morphology (Figure 2c) was observed after TBAOH treatment and filtration, further confirmed by parallel stacking as shown in the cross-section image (Figure S4). The TEM image (Figure 2d) shows transparent Ti3C2Tx sheets with well-defined and clean edges, with the lateral size around 600 nm. The selected area electron diffraction pattern (SAED) (Figure 2e) shows sharp reflections indexed with a hexagonal crystal system indicating that the TBAOH treatment does not alter the crystallinity of the Ti3C2Tx nanosheets. (21) The high-resolution TEM (HRTEM) image in Figure 2f confirms the thickness is around 2.05 nm, corresponding to ∼2 layers considering the thickness of the monolayer (∼1.03 nm). (22,23) These samples with expanded interlayer distance will be further termed as e-MS-Ti3C2Tx. Zeta-potential (ζ) measurements of MS-Ti3C2Tx suspensions before and after TBAOH treatment have been made in water at different pH to determine the surface charge and the fundamental interaction between the particles. As shown in Figure 2g, a negative ζ was measured in a pH range from 2.9 to 10.2 varying from 0 to −67 mV. The maximum zeta potential (absolute value) is almost twice that of DMSO-treated HF-Ti3C2Tx, (16) but similar to TBAOH-treated HF-Ti3CNTx. (19) The isoelectric point is located at pH 2.9, which is far away from the pH of e-MS-Ti3C2Tx (pH = 7.6) in water. The strong electrostatic repulsion between highly negatively charged e-Ti3C2Tx nanosheets results in a stable colloidal suspension by limiting aggregation, such as previously observed for DMSO-treated HF-MXene. (16) Differently from e-MS-Ti3C2Tx, the zeta potential of pristine MS-Ti3C2Tx is nearly 0 mV as a function of pH (Figure 2h), as the result of the instability of the pristine MS-Ti3C2Tx suspension after a couple of hours. Finally, the determination of the particle size (Figure 2i) shows, after TBAOH treatment and sonication, a size range from 200 to 1000 nm with the distribution of peak positions at 600 nm, which corresponds well with the TEM results (Figure 2d).
图 2a 显示了 MAX 相前驱体（黑色图）、从熔盐浴中取出后的 MXene（红色图）和 APS 洗涤以去除 Cu 后的 MXene（蓝色图）以及 TBAOH 剥离处理后的 MXene（绿色）的 X 射线衍射 （XRD） 图谱。合成后（图 2a，红图），对应于原始 Ti 3 AlC 2 MAX 前驱体的大部分衍射峰消失，留下 （00l） 峰以及 5° 至 80° 范围内 2θ 范围内的几个宽峰和低强度峰。这些特征表明 Al 层成功地从 Ti 3 AlC 2 蚀刻成层状 Ti 3 C 2 。此外，Ti 3 C 2 （002） 衍射峰从 2θ = 9.63° 偏移到 8.07° （±0.02°） 表明层间距离从 9.17 Å 扩展到 10.98 Å （±0.03 Å）。以 43.29°、50.43° 和 74.13° 的 2θ 角为中心的新形成的尖锐而强烈的峰可以识别为金属 Cu。用 APS （（NH 4 ） 2 S 2 O 8 ） 溶液洗涤后的 XRD 图谱仅显示 （001） 由于去除了铜而产生的峰（图 2a，蓝色图）。经过 TBAOH 处理和冷冻干燥后，XRD 图谱中 MS-Ti 3 C 2 T x 的主峰仍然存在（图 2a，绿色图），证明了 Ti 3 C 2 T x 。（002） 和 （004） 峰的低强度表明，冻干 TBAOH 处理的 MS-MXene 薄片位于不同的方向。此外，（002） 和 （004） 峰的 （002） 和 （004） 峰分别从 8.07° 和 16.14° 略微偏移至 15.62°。这表明 TBA 阳离子嵌入后 MS-MXene 结构略有膨胀，从 10.94 Å（纯）扩展到 11。31 Å （TBAOH 处理后）。同时，观察到轻微的峰展宽，表明片状尺寸较小。（20） 与原始 MS-Ti 3 C 2 T x 的手风琴状多层形态不同（图 2b），在 TBAOH 处理和过滤后观察到平行的重新堆叠分层形态（图 2c），通过平行堆叠进一步证实，如横截面图所示（图 S4）。TEM 图像（图 2d）显示了透明的 Ti 3 C 2 T x 片材，具有清晰和干净的边缘，横向尺寸约为 600 nm。所选区域电子衍射图 （SAED）（图 2e）显示了以六边形晶体系统为索引的尖锐反射，表明 TBAOH 处理不会改变 Ti 3 C 2 T x 纳米片的结晶度。（21） 图 2f 中的高分辨率 TEM （HRTEM） 图像证实厚度约为 2.05 nm，考虑到单层的厚度 （∼1.03 nm），对应于 ∼2 层。（22,23） 这些层间距离扩大的样品将进一步称为 e-MS-Ti 3 C 2 T x 。在不同 pH 值的水中对 TBAOH 处理前后的 MS-Ti 3 C 2 T x 悬浮液进行 Zeta 电位 （ζ） 测量，以确定表面电荷和颗粒之间的基本相互作用。如图 2g 所示，在 2.9 至 10.2 的 pH 范围内测得负ζ，变化范围为 0 至 −67 mV。最大 zeta 电位（绝对值）几乎是 DMSO 处理的 HF-Ti 3 C 2 T x 的两倍，（16），但与 TBAOH 处理的 HF-Ti 3 CNT x 相似。（19） 等电点位于 pH 2 处。9，与水中 e-MS-Ti 3 C 2 T x 的 pH 值 （pH = 7.6） 相去甚远。高负电荷的 e-Ti 3 C 2 T x 纳米片之间的强静电排斥通过限制聚集产生稳定的胶体悬浮液，例如之前在 DMSO 处理的 HF-MXene 中观察到的那样。（16） 与 e-MS-Ti 3 C 2 T x 不同，原始 MS-Ti 3 C 2 T x 的 zeta 电位与 pH 值的函数关系接近 0 mV（图 2h），这是原始 MS-Ti 3 C 2 T x 悬浮液在几个小时后不稳定的结果。最后，粒径的测定（图 2i）显示，在 TBAOH 处理和超声处理后，粒径范围为 200 至 1000 nm，峰位置分布在 600 nm，这与 TEM 结果非常吻合（图 2d）。
图 2a 显示了 MAX 相前驱体（黑色图）、从熔盐浴中取出后的 MXene（红色图）和 APS 洗涤以去除 Cu 后的 MXene（蓝色图）以及 TBAOH 剥离处理后的 MXene（绿色）的 X 射线衍射 （XRD） 图谱。合成后（图 2a，红图），对应于原始 Ti 3 AlC 2 MAX 前驱体的大部分衍射峰消失，留下 （00l） 峰以及 5° 至 80° 范围内 2θ 范围内的几个宽峰和低强度峰。这些特征表明 Al 层成功地从 Ti 3 AlC 2 蚀刻成层状 Ti 3 C 2 。此外，Ti 3 C 2 （002） 衍射峰从 2θ = 9.63° 偏移到 8.07° （±0.02°） 表明层间距离从 9.17 Å 扩展到 10.98 Å （±0.03 Å）。以 43.29°、50.43° 和 74.13° 的 2θ 角为中心的新形成的尖锐而强烈的峰可以识别为金属 Cu。用 APS （（NH 4 ） 2 S 2 O 8 ） 溶液洗涤后的 XRD 图谱仅显示 （001） 由于去除了铜而产生的峰（图 2a，蓝色图）。经过 TBAOH 处理和冷冻干燥后，XRD 图谱中 MS-Ti 3 C 2 T x 的主峰仍然存在（图 2a，绿色图），证明了 Ti 3 C 2 T x 。（002） 和 （004） 峰的低强度表明，冻干 TBAOH 处理的 MS-MXene 薄片位于不同的方向。此外，（002） 和 （004） 峰的 （002） 和 （004） 峰分别从 8.07° 和 16.14° 略微偏移至 15.62°。这表明 TBA 阳离子嵌入后 MS-MXene 结构略有膨胀，从 10.94 Å（纯）扩展到 11。31 Å （TBAOH 处理后）。同时，观察到轻微的峰展宽，表明片状尺寸较小。（20） 与原始 MS-Ti 3 C 2 T x 的手风琴状多层形态不同（图 2b），在 TBAOH 处理和过滤后观察到平行的重新堆叠分层形态（图 2c），通过平行堆叠进一步证实，如横截面图所示（图 S4）。TEM 图像（图 2d）显示了透明的 Ti 3 C 2 T x 片材，具有清晰和干净的边缘，横向尺寸约为 600 nm。所选区域电子衍射图 （SAED）（图 2e）显示了以六边形晶体系统为索引的尖锐反射，表明 TBAOH 处理不会改变 Ti 3 C 2 T x 纳米片的结晶度。（21） 图 2f 中的高分辨率 TEM （HRTEM） 图像证实厚度约为 2.05 nm，考虑到单层的厚度 （∼1.03 nm），对应于 ∼2 层。（22,23） 这些层间距离扩大的样品将进一步称为 e-MS-Ti 3 C 2 T x 。在不同 pH 值的水中对 TBAOH 处理前后的 MS-Ti 3 C 2 T x 悬浮液进行 Zeta 电位 （ζ） 测量，以确定表面电荷和颗粒之间的基本相互作用。如图 2g 所示，在 2.9 至 10.2 的 pH 范围内测得负ζ，变化范围为 0 至 −67 mV。最大 zeta 电位（绝对值）几乎是 DMSO 处理的 HF-Ti 3 C 2 T x 的两倍，（16），但与 TBAOH 处理的 HF-Ti 3 CNT x 相似。（19） 等电点位于 pH 2 处。9，与水中 e-MS-Ti 3 C 2 T x 的 pH 值 （pH = 7.6） 相去甚远。高负电荷的 e-Ti 3 C 2 T x 纳米片之间的强静电排斥通过限制聚集产生稳定的胶体悬浮液，例如之前在 DMSO 处理的 HF-MXene 中观察到的那样。（16） 与 e-MS-Ti 3 C 2 T x 不同，原始 MS-Ti 3 C 2 T x 的 zeta 电位与 pH 值的函数关系接近 0 mV（图 2h），这是原始 MS-Ti 3 C 2 T x 悬浮液在几个小时后不稳定的结果。最后，粒径的测定（图 2i）显示，在 TBAOH 处理和超声处理后，粒径范围为 200 至 1000 nm，峰位置分布在 600 nm，这与 TEM 结果非常吻合（图 2d）。
Figure 2 图 2
Figure 2. Material characterization of e-MS-Ti3C2Tx. (a) XRD patterns of pristine Ti3AlC2 before (black line) and after (red line) reaction with CuCl2, multilayered MS-Ti3C2Tx (blue line), and e-MS-Ti3C2Tx (green line) TBAOH treatment. SEM graph of (b) MS-Ti3C2Tx MXene and (c) e-MS-Ti3C2Tx (collected by filtration). (d) TEM graph of e-MS-Ti3C2Tx. (e) Selected area electron diffraction (SAED) pattern and (f) HRTEM image of e-MS-Ti3C2Tx. Zeta potentials of (g) e-MS-Ti3C2Tx and (h) multilayered MS-Ti3C2Tx. (i) Mean size of multilayered MS-Ti3C2Tx (gray line) and e-MS-Ti3C2Tx (red line) in DI water.
图 2.e-MS-Ti 3 C 2 、T x 的材料表征。（a） 与 CuCl 反应前（黑线）和后（红线）原始 Ti 3 AlC 2 的 XRD 图谱 2 ，多层 MS-Ti 3 C 2 T x （蓝线）和 e-MS-Ti 3 C 2 T x （绿线）TBAOH 处理。（b） MS-Ti 3 C 2 T x MXene 和 （c） e-MS-Ti 3 C 2 T x （通过过滤收集）的 SEM 图。（d） e-MS-Ti 3 C 2 T x 的 TEM 图。（e） 选定区域电子衍射 （SAED） 图样和 （f） e-MS-Ti 3 C 2 T x 的 HRTEM 图像。（g） e-MS-Ti 3 C 2 T x 和 （h） 多层 MS-Ti 3 C 2 T x 的 Zeta 电位。（i） 去离子水中多层 MS-Ti 3 C 2 T x （灰线）和 e-MS-Ti 3 C 2 T x （红线）的平均尺寸。
Electrochemical Characterizations
电化学表征
A series of electrochemical characterizations were performed to evaluate the electrochemical performance of freeze-dried e-MS-Ti3C2Tx. Figure 3a shows the initial two cyclic voltammetry (CV) cycles recorded at 1 mV s–1 in LP30 electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate with 1:1 volume ratio). During the first cycle, an irreversible capacity loss is observed upon reduction (lithiation) due to the formation of the solid electrolyte interphase (SEI) layer. (24) The SEI layer formation at the first cycle decreases the Coulombic efficiency down to 36%, as a result of the increased electrochemical surface area. Although we did not focus on that specific point, the Coulombic efficiency at the first cycle could be improved by postannealing treatment for instance. (25) In the subsequent cycle, CV shows a mirror-like shape with no redox peak during Li intercalation/deintercalation reactions, similarly to what we previously observed for pristine MS-Ti3C2Tx (Figure S5a, see also ref (13)). In Figure 3b, an almost constant current was observed during the oxidation process from 1 mV s–1 to 200 mV s–1 in a potential range between 0.2 and 2.0 V versus Li+/Li, indicating a reversible behavior for the freeze-dried e-MS-Ti3C2Tx. The discharge capacity of freeze-dried e-MS-Ti3C2Tx is 225 and 95 mA h g–1 at current densities of 0.2 and 16 A g–1, respectively (Figure 3c), corresponding to an impressive ∼42% capacity retention after 80 increases of current density. Comparatively, the discharge capacities of pristine MS-Ti3C2Tx can only reach 205 and 25 mA h g–1 at current densities of 0.2 and 16 A g–1, respectively (Figure S5c). Figure 3d compares the specific capacity of MS-Ti3C2Tx before and after TBAOH treatment at different C-rates calculated from the galvanostatic charge–discharge profiles (Figures 3c and S5c), where both electrodes have a similar weight loading of 1.1 mg cm–2. The capacity retention of e-MS-Ti3C2Tx reaches 42% from 0.2 to 16 A g–1, while pristine MS-Ti3C2Tx with similar weight loading shows only 15% retention in the same current range due to slow kinetics even at 20 mV s–1. Those numbers evidence the higher power capability of the e-MS-Ti3C2Tx, which can be explained by the improved electrochemically accessible specific surface area of e-MS-Ti3C2Tx and faster ion transport. (26) EDS analysis of the e-MS-Ti3C2Tx shows that the main effect of the TBAOH treatment is the −O content increases (see Table S1), indicating the possible −O group addition due to the dissolved oxygen during the 6 h sonification process. These results agree well with the result of density functional theory (DFT) stimulations showing that O-terminated Ti3C2 MXene exhibits the highest theoretical Li ion storage capacity. (27) The cycling stability of the e-MS-Ti3C2Tx was evaluated at a current density of 4 A g–1. A capacity of about 85 mA h g–1 was still delivered after 2000 cycles (Figure S6), corresponding to a capacity retention of 72%. Moreover, the electrochemical performance of TBAOH-treated MXene is also strongly affected by the drying methods. (28) While oven-dried (80 °C for 12 h) e-MS-Ti3C2Tx has a similar electrochemical signature to the freeze-dried one (Figure S7a), the gravimetric capacity and power performance are strongly affected (Figure S7b and c) as a result of limited Li-ion transport in the electrode structure due to the stacking of oven-dried e-Ti3C2Tx layers, (28) supported by the presence of sharp (002) and (004) peaks in the XRD pattern in Figure S8. In addition, the electrochemical performance of freeze-dried MS-Ti3C2Tx has also been evaluated to evidence the significance of TBAOH treatment. As shown in Figure S9, without TBAOH treatment, freeze-dried MS-Ti3C2Tx shows a similar capacity (180 mAh g–1) and low power capability to that observed for oven-dried MS-Ti3C2Tx.
进行了一系列电化学表征，以评价冻干 e-MS-Ti 3 C 2 T x 的电化学性能。图 3a 显示了在 LP30 电解液中以 1 mV s –1 记录的初始两个循环伏安法 （CV） 循环（1 M LiPF 6 在碳酸乙烯酯/碳酸二甲酯中，体积比为 1：1）。在第一个循环中，由于固体电解质界面 （SEI） 层的形成，在还原（锂化）时观察到不可逆的容量损失。（24） 由于电化学表面积增加，在第一个循环中形成 SEI 层将库仑效率降低到 36%。虽然我们没有关注那个特定的点，但例如，可以通过后退火处理来提高第一个周期的库仑效率。（25） 在随后的循环中，CV 在 Li 嵌入/脱嵌反应过程中呈镜状形状，没有氧化还原峰，类似于我们之前观察到的原始 MS-Ti 3 C 2 T x （图 S5a，另见参考文献 （13））。在图 3b 中，在 0.2 至 2.0 V 的电位范围内，从 1 mV s –1 到 200 mV s –1 的氧化过程中观察到几乎恒定的电流，表明 + 冻干 e-MS-Ti 3 C 2 T x 的行为是可逆的。在电流密度为 0.2 和 16 A g 时，冻干 e-MS-Ti 3 C 2 T x 的放电容量分别为 225 和 95 mA h g –1 （图 3c），相当于在电流密度增加 80 次后令人印象深刻的 ∼42% 容量保持率。 –1 相比之下，原始 MS-Ti 3 C 2 T x 的放电容量在 0.2 和 16 A g –1 的电流密度下分别只能达到 205 和 25 mA h g –1 （图 S5c）。图 3d 比较了 TBAOH 处理前后 MS-Ti 3 C 2 T x 在根据恒电流充放电曲线计算的不同 C 速率下的比容量（图 3c 和 S5c），其中两个电极具有相似的 1.1 mg cm –2 重量负载。e-MS-Ti 3 C 2 T x 的容量保持率在 0.2 至 16 A g –1 范围内达到 42%，而具有相似重量负载的原始 MS-Ti 3 C 2 T x 在相同电流范围内仅显示出 15% 的保留率，因为即使在 20 mV s –1 下动力学也很慢。这些数字证明了 e-MS-Ti 3 C 2 T x 具有更高的功率能力，这可以通过 e-MS-Ti 3 C 2 T x 的电化学可及比表面积的改善和更快的离子传输来解释。（26） e-MS-Ti 3 C 2 T x 的 EDS 分析表明，TBAOH 处理的主要效果是 -O 含量增加（见表 S1），表明在 6 小时超声化过程中由于溶解氧可能添加 -O 基团。这些结果与密度泛函理论 （DFT） 刺激的结果非常吻合，该结果表明 O 封端的 Ti 3 C 2 MXene 表现出最高的理论锂离子存储容量。（27） 在 4 A g –1 的电流密度下评估了 e-MS-Ti 3 C 2 T x 的循环稳定性。 2000 次循环后仍提供约 85 mA h g –1 的容量（图 S6），对应于 72% 的容量保持。此外，TBAOH 处理的 MXene 的电化学性能也受到干燥方法的强烈影响。（28） 虽然烘箱干燥（80 °C 12 小时）e-MS-Ti 3 C 2 T x 具有与冻干相似的电化学特征（图 S7a），但由于烘箱干燥的 e-Ti 3 C 2 T x 的堆叠，电极结构中的锂离子传输受到限制，因此重量容量和功率性能受到强烈影响（图 S7b 和 c）层 （28） 由图 S8 中 XRD 图谱中存在尖锐 （002） 和 （004） 峰支持。此外，还评估了冻干 MS-Ti 3 C 2 T x 的电化学性能，以证明 TBAOH 处理的重要性。如图 S9 所示，未经 TBAOH 处理，冻干 MS-Ti 3 C 2 T x 显示出与烘箱干燥的 MS-Ti 3 C 2 T x 相似的容量 （180 mAh g –1 ） 和低功耗能力。
进行了一系列电化学表征，以评价冻干 e-MS-Ti 3 C 2 T x 的电化学性能。图 3a 显示了在 LP30 电解液中以 1 mV s –1 记录的初始两个循环伏安法 （CV） 循环（1 M LiPF 6 在碳酸乙烯酯/碳酸二甲酯中，体积比为 1：1）。在第一个循环中，由于固体电解质界面 （SEI） 层的形成，在还原（锂化）时观察到不可逆的容量损失。（24） 由于电化学表面积增加，在第一个循环中形成 SEI 层将库仑效率降低到 36%。虽然我们没有关注那个特定的点，但例如，可以通过后退火处理来提高第一个周期的库仑效率。（25） 在随后的循环中，CV 在 Li 嵌入/脱嵌反应过程中呈镜状形状，没有氧化还原峰，类似于我们之前观察到的原始 MS-Ti 3 C 2 T x （图 S5a，另见参考文献 （13））。在图 3b 中，在 0.2 至 2.0 V 的电位范围内，从 1 mV s –1 到 200 mV s –1 的氧化过程中观察到几乎恒定的电流，表明 + 冻干 e-MS-Ti 3 C 2 T x 的行为是可逆的。在电流密度为 0.2 和 16 A g 时，冻干 e-MS-Ti 3 C 2 T x 的放电容量分别为 225 和 95 mA h g –1 （图 3c），相当于在电流密度增加 80 次后令人印象深刻的 ∼42% 容量保持率。 –1 相比之下，原始 MS-Ti 3 C 2 T x 的放电容量在 0.2 和 16 A g –1 的电流密度下分别只能达到 205 和 25 mA h g –1 （图 S5c）。图 3d 比较了 TBAOH 处理前后 MS-Ti 3 C 2 T x 在根据恒电流充放电曲线计算的不同 C 速率下的比容量（图 3c 和 S5c），其中两个电极具有相似的 1.1 mg cm –2 重量负载。e-MS-Ti 3 C 2 T x 的容量保持率在 0.2 至 16 A g –1 范围内达到 42%，而具有相似重量负载的原始 MS-Ti 3 C 2 T x 在相同电流范围内仅显示出 15% 的保留率，因为即使在 20 mV s –1 下动力学也很慢。这些数字证明了 e-MS-Ti 3 C 2 T x 具有更高的功率能力，这可以通过 e-MS-Ti 3 C 2 T x 的电化学可及比表面积的改善和更快的离子传输来解释。（26） e-MS-Ti 3 C 2 T x 的 EDS 分析表明，TBAOH 处理的主要效果是 -O 含量增加（见表 S1），表明在 6 小时超声化过程中由于溶解氧可能添加 -O 基团。这些结果与密度泛函理论 （DFT） 刺激的结果非常吻合，该结果表明 O 封端的 Ti 3 C 2 MXene 表现出最高的理论锂离子存储容量。（27） 在 4 A g –1 的电流密度下评估了 e-MS-Ti 3 C 2 T x 的循环稳定性。 2000 次循环后仍提供约 85 mA h g –1 的容量（图 S6），对应于 72% 的容量保持。此外，TBAOH 处理的 MXene 的电化学性能也受到干燥方法的强烈影响。（28） 虽然烘箱干燥（80 °C 12 小时）e-MS-Ti 3 C 2 T x 具有与冻干相似的电化学特征（图 S7a），但由于烘箱干燥的 e-Ti 3 C 2 T x 的堆叠，电极结构中的锂离子传输受到限制，因此重量容量和功率性能受到强烈影响（图 S7b 和 c）层 （28） 由图 S8 中 XRD 图谱中存在尖锐 （002） 和 （004） 峰支持。此外，还评估了冻干 MS-Ti 3 C 2 T x 的电化学性能，以证明 TBAOH 处理的重要性。如图 S9 所示，未经 TBAOH 处理，冻干 MS-Ti 3 C 2 T x 显示出与烘箱干燥的 MS-Ti 3 C 2 T x 相似的容量 （180 mAh g –1 ） 和低功耗能力。
Figure 3 图 3
Figure 3. Electrochemical characterization in 1 M LiPF6 in ethylene carbonate/dimethyl carbonate electrolyte of e-MS-Ti3C2Tx with a mass loading of around 1.1 mg cm–2. (a) First three CV cycles recorded at 1 mV s–1. (b) CVs recorded at various potential scan rates from 1 to 200 mV s–1. (c) Galvanostatic charge–discharge (GCD) curves recorded at various current density from 0.2 to 16 A g–1. (d) Discharge time and capacity values of a multilayer before (black line) and after (red line) TBAOH treatment from 0.2 A g–1 (1C) to 16 A g–1 (167.5C).
图 3.e-MS-Ti C T 6 的 e-MS-Ti C 2 T x 电解质中 1 M LiPF 的电化学表征 –2 。 3 （a） 在 1 mV s –1 处记录的前三个 CV 周期。（b） 以 1 至 200 mV s –1 的各种潜在扫描速率记录的 CV。（c） 在 0.2 至 16 A g –1 的各种电流密度下记录的恒电流充放电 （GCD） 曲线。（d） TBAOH 处理之前（黑线）和之后（红线）多层的放电时间和容量值，从 0.2 A g –1 （1C） 到 16 A g –1 （167.5C）。
Interface Modification of MS-Ti3C2Tx
MS-Ti 3 C 2 T x 的界面修饰
Differently from the hydrophilic HF-MXene, (28) pristine MS-MXene has a hydrophobic surface due to the absence of a −OH group on the surface. To further characterize the change of surface properties, water contact angle measurements were performed on an MS-MXene electrode film (prepared by mixing 80 wt % of MXene powders together with 15 wt % of carbon black and 5 wt % of PTFE binder) before and after TBAOH treatment. As shown in Figure 4a, different TBAOH treatment times lead to distinct wetting behavior of MS-Ti3C2Tx. The pristine MS-Ti3C2Tx film presents a hydrophobic nature with a water contact angle of 136°, whereas the MS-Ti3C2Tx samples after TBAOH treatment show a decreasing contact angle with the TBAOH treatment time (see Figure 4a). The water contact angle (WCA) values were 118°, 95°, and 23° for 12, 24 and 72 h treatment times, respectively, indicating that the hydrophilicity increases with longer TBAOH treatment time. According to the report of Liu etal., (30) the hydrophilicity of MXene materials can be improved by introducing oxygen-containing polar groups. In the present case, the immersion in strong TBAOH base may result in slow surface oxidation of the MXene surface into hydroxyl groups under a prolonged sonication process, possibly by dissolved oxygen. (29) To further understand the evolution of MS-MXene in TBAOH solution, TEM observations and electrochemical measurements were successively performed on the MS-Ti3C2Tx after TBAOH treatment for 24 and 72 h. As shown in Figure S10, some black dots were present on both basal and edge planes of MS-Ti3C2Tx sheets after 24 h, and large defects and nanoparticles of about 50 nm diameter can be observed after 72 h. Moreover, a new peak at 25.2° corresponding to anatase TiO2 can be observed in the XRD patterns (see Figure S11a) of MS-Ti3C2Tx after 72 h of treatment in TBAOH solution, indicating that Ti3C2Tx slowly oxidized into TiO2 (PDF#00-021-1272). (9,31) This is supported by the electrochemical signature of MS-Ti3C2Tx, where a broad cathodic peak at 1.2 V and anodic peak at 2.1 V observed with increasing the treatment time (Figure S11b) could be attributed to the (de)lithiation behavior of TiO2. (9)
与亲水性 HF-MXene 不同，（28） 原始 MS-MXene 由于表面不存在 −OH 基团，因此具有疏水表面。为了进一步表征表面特性的变化，在 TBAOH 处理前后对 MS-MXene 电极膜（通过将 80 wt % 的 MXene 粉末与 15 wt % 的炭黑和 5 wt% 的 PTFE 粘合剂混合制备）进行水接触角测量。如图 4a 所示，不同的 TBAOH 处理时间导致 MS-Ti 3 C 2 T x 的不同润湿行为。原始的 MS-Ti 3 C 2 T x 薄膜具有疏水性，水接触角为 136°，而 TBAOH 处理后的 MS-Ti 3 C 2 T x 样品显示接触角随 TBAOH 处理时间的减少（见图 4a）。12 、 24 和 72 h 处理时间的水接触角 （WCA） 值分别为 118° 、 95° 和 23°，表明亲水性随着 TBAOH 处理时间的延长而增加。根据 Liu 等人的报告，（30） 通过引入含氧极性基团可以提高 MXene 材料的亲水性。在目前的情况下，浸泡在强 TBAOH 碱中可能导致在长时间的超声处理过程中，MXene 表面缓慢地表面氧化成羟基，可能是通过溶解氧。（29） 为了进一步了解 MS-MXene 在 TBAOH 溶液中的演变，在 TBAOH 处理 24 和 72 h 后，先后对 MS-Ti 3 C 2 T x 进行了 TEM 观察和电化学测量。 如图 S10 所示，24 小时后，MS-Ti 3 C 2 T x 片材的基平面和边缘平面上都存在一些黑点，72 小时后可以观察到直径约为 50 nm 的大缺陷和纳米颗粒。此外，在 TBAOH 溶液中处理 72 小时后，在 MS-Ti C T 的 XRD 图谱（参见图 S11a）中可以观察到对应于锐钛矿 TiO 2 的 25.2° 新峰，表明 Ti 3 C 2 T x 缓慢氧化成 TiO 2 （PDF#00-021-1272）。 x 2 3 （9,31） MS-Ti 3 C 2 T x 的电化学特征支持了这一点，其中随着处理时间的增加，在 1.2 V 处观察到宽阴极峰，在 2.1 V 处观察到阳极峰（图 S11b）可归因于 TiO 2 的（去）锂化行为。 (9)
与亲水性 HF-MXene 不同，（28） 原始 MS-MXene 由于表面不存在 −OH 基团，因此具有疏水表面。为了进一步表征表面特性的变化，在 TBAOH 处理前后对 MS-MXene 电极膜（通过将 80 wt % 的 MXene 粉末与 15 wt % 的炭黑和 5 wt% 的 PTFE 粘合剂混合制备）进行水接触角测量。如图 4a 所示，不同的 TBAOH 处理时间导致 MS-Ti 3 C 2 T x 的不同润湿行为。原始的 MS-Ti 3 C 2 T x 薄膜具有疏水性，水接触角为 136°，而 TBAOH 处理后的 MS-Ti 3 C 2 T x 样品显示接触角随 TBAOH 处理时间的减少（见图 4a）。12 、 24 和 72 h 处理时间的水接触角 （WCA） 值分别为 118° 、 95° 和 23°，表明亲水性随着 TBAOH 处理时间的延长而增加。根据 Liu 等人的报告，（30） 通过引入含氧极性基团可以提高 MXene 材料的亲水性。在目前的情况下，浸泡在强 TBAOH 碱中可能导致在长时间的超声处理过程中，MXene 表面缓慢地表面氧化成羟基，可能是通过溶解氧。（29） 为了进一步了解 MS-MXene 在 TBAOH 溶液中的演变，在 TBAOH 处理 24 和 72 h 后，先后对 MS-Ti 3 C 2 T x 进行了 TEM 观察和电化学测量。 如图 S10 所示，24 小时后，MS-Ti 3 C 2 T x 片材的基平面和边缘平面上都存在一些黑点，72 小时后可以观察到直径约为 50 nm 的大缺陷和纳米颗粒。此外，在 TBAOH 溶液中处理 72 小时后，在 MS-Ti C T 的 XRD 图谱（参见图 S11a）中可以观察到对应于锐钛矿 TiO 2 的 25.2° 新峰，表明 Ti 3 C 2 T x 缓慢氧化成 TiO 2 （PDF#00-021-1272）。 x 2 3 （9,31） MS-Ti 3 C 2 T x 的电化学特征支持了这一点，其中随着处理时间的增加，在 1.2 V 处观察到宽阴极峰，在 2.1 V 处观察到阳极峰（图 S11b）可归因于 TiO 2 的（去）锂化行为。 (9)
Figure 4 图 4
Figure 4. Evolution of MS-Ti3C2Tx in TBAOH and TMAOH. (a) Water contact angle of MS-Ti3C2Tx treated by TBAOH for 0, 12, 24, and 72 h, respectively. (b) SEM image of MS-Ti3C2Tx MXene after TMAOH treatment for 72 h, followed by an 18 h bath sonification and selection at 7000 rpm. (c) Photo showing the flexibility of the filtrated TMAOH-treated MS-MXene after selection.
图 4.TBAOH 和 TMAOH 中 MS-Ti 3 C 2 T x 的演变。（a） TBAOH 处理 MS-Ti 3 C 2 T x 的水接触角分别为 0、12、24 和 72 h。（b） TMAOH 处理 72 小时后 MS-Ti 3 C 2 T x MXene 的 SEM 图像，然后在 7000 rpm 下进行 18 小时的浴超声化和选择。（c） 照片显示了筛选后过滤的 TMAOH 处理的 MS-MXene 的柔韧性。
It was reported that hydroxyl groups play a significant role in the delamination of MXene. (32) Therefore, a more hydrophilic TMAOH, due to the shorter chain size, has been chosen to treat MS-Ti3C2Tx for 72 h, followed by an 18 h bath sonification and selection by centrifugation at 7000 rpm. As shown in Figure 4b and c, free-standing Ti3C2Tx paper could be prepared by filtration of the suspension onto a porous membrane, leading to the production of an MS-MXene self-supported thin film. The water contact angle of the above free-standing film is measured to be 24.2° (see Figure S12), which evidences its more hydrophilic surface. However, the filtered electrode shows poor electrochemical performance in 1 M LiPF6 in an ethylene carbonate/dimethyl carbonate electrolyte (Figure S13) as a result of hydrophilic surface groups and the compact layered structure, which limits full access of the electrolyte ions between the MXene layers.
据报道，羟基在 MXene 的分层中起重要作用。（32） 因此，由于链尺寸较短，选择更亲水性的 TMAOH 处理 MS-Ti 3 C 2 T x 72 小时，然后进行 18 小时的浴超声化，并通过 7000 rpm 离心进行选择。如图 4b 和 c 所示，可以通过将悬浮液过滤到多孔膜上来制备独立的 Ti 3 C 2 T x 纸，从而产生 MS-MXene 自支撑薄膜。上述独立式薄膜的水接触角测量为 24.2°（见图 S12），这证明了其更亲水的表面。然而，由于亲水表面基团和紧凑的层状结构，过滤电极在碳酸乙烯酯/碳酸二甲酯电解质 6 中的 1 M LiPF 中显示出较差的电化学性能（图 S13），这限制了电解质离子在 MXene 层之间的完全进入。
据报道，羟基在 MXene 的分层中起重要作用。（32） 因此，由于链尺寸较短，选择更亲水性的 TMAOH 处理 MS-Ti 3 C 2 T x 72 小时，然后进行 18 小时的浴超声化，并通过 7000 rpm 离心进行选择。如图 4b 和 c 所示，可以通过将悬浮液过滤到多孔膜上来制备独立的 Ti 3 C 2 T x 纸，从而产生 MS-MXene 自支撑薄膜。上述独立式薄膜的水接触角测量为 24.2°（见图 S12），这证明了其更亲水的表面。然而，由于亲水表面基团和紧凑的层状结构，过滤电极在碳酸乙烯酯/碳酸二甲酯电解质 6 中的 1 M LiPF 中显示出较差的电化学性能（图 S13），这限制了电解质离子在 MXene 层之间的完全进入。
Conclusions 结论
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
In this paper, TBAOH was selected as a solvent for the exfoliation of MS-Ti3C2Tx. During the process, ion exchange between the bulky tetraalkylammonium ions (TBA+) and cations (protons and K-ions) is assumed to allow a bulky TBA+ cation to access the interlayer space, resulting in further exfoliation from multi- to few-layer MXene. The TBAOH-treated MS-Ti3C2Tx nanosheet suspension was found to be stable for 2 weeks, without apparent precipitation. When TBAOH-treated MS-Ti3C2Tx was tested as an anode material in a Li-ion battery, a high specific capacity of 225 mAh g–1 at 1C and excellent rate capability of 95 mAh g–1 at 167C could be achieved, indicating improved electrochemical performance versus multilayered (pristine) MS-Ti3C2Tx. Interestingly, TBAOH treatment resulted in the change of the wettability of MS-MXene, as evidenced from the decrease of contact angle with the duration of TBAOH treatment time. Moreover, a self-supported Cl-terminated MXene film could be prepared by filtration.
在本文中，TBAOH 被选为 MS-Ti 3 C 2 T x 剥离的溶剂。在此过程中，假设大体积的四烷基铵离子 （TBA + ） 和阳离子（质子和 K 离子）之间的离子交换允许大体积的 TBA + 阳离子进入层间空间，从而导致从多层 MXene 进一步剥离到几层 MXene。发现 TBAOH 处理的 MS-Ti 3 C 2 T x 纳米片悬浮液稳定 2 周，无明显沉淀。当 TBAOH 处理的 MS-Ti 3 C 2 T x 作为锂离子电池中的负极材料进行测试时，在 1C 时可以实现 225 mAh g –1 的高比容量，在 167C 时可以实现 95 mAh g –1 的出色倍率能力，表明与多层（原始）MS-Ti 3 C 2 T x 相比，电化学性能更高.有趣的是，TBAOH 处理导致 MS-MXene 润湿性发生变化，接触角随 TBAOH 处理时间的持续时间而减小证明。此外，可以通过过滤制备自支撑的 Cl 封端 MXene 薄膜。
在本文中，TBAOH 被选为 MS-Ti 3 C 2 T x 剥离的溶剂。在此过程中，假设大体积的四烷基铵离子 （TBA + ） 和阳离子（质子和 K 离子）之间的离子交换允许大体积的 TBA + 阳离子进入层间空间，从而导致从多层 MXene 进一步剥离到几层 MXene。发现 TBAOH 处理的 MS-Ti 3 C 2 T x 纳米片悬浮液稳定 2 周，无明显沉淀。当 TBAOH 处理的 MS-Ti 3 C 2 T x 作为锂离子电池中的负极材料进行测试时，在 1C 时可以实现 225 mAh g –1 的高比容量，在 167C 时可以实现 95 mAh g –1 的出色倍率能力，表明与多层（原始）MS-Ti 3 C 2 T x 相比，电化学性能更高.有趣的是，TBAOH 处理导致 MS-MXene 润湿性发生变化，接触角随 TBAOH 处理时间的持续时间而减小证明。此外，可以通过过滤制备自支撑的 Cl 封端 MXene 薄膜。
Experimental Section 实验部分
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
Preparation of MS-MXenes MS-MXenes 的制备
Ti3AlC2 was used as the MAX phase precursor, and CuCl2 (Sigma-Aldrich, CAS # 7447-39-4), NaCl (Sigma-Aldrich, CAS # 7647-14-5), and KCl (Sigma-Aldrich, CAS # 7447-40-7) were selected as the molten salt. In a typical procedure, Ti3AlC2 was mixed with molten salt according to the following ratio (Ti3AlC2:CuCl2:NaCl:KCl = 1:3:2:2 molar ratio) and ground well for 10 min in air to make sure the mixture was homogeneous. Then the mixture was heated to 680 °C at a heating ramp of 4 °C/min under flowing argon in a tube furnace for 24 h. The resulting reddish-brown products were washed using deionized water and collected by vacuum filtration with a porous anodic aluminum oxide membrane filter (47 mm diameter, 0.2 mm pore size, Whatman Anodisc, Maidstone, UK). Afterward, an APS ((NH4)2S2O8, Sigma-Aldrich, CAS # 7727-54-0) solution was prepared and added inside to further dissolve the residual Cu. Finally, the above products were collected by vacuum filtration after cleaning by deionized water and then dried in a vacuum oven at 80 °C overnight.
以 Ti 3 AlC 2 作为 MAX 相前驱体，选择 CuCl 2 （Sigma-Aldrich， CAS # 7447-39-4）、NaCl （Sigma-Aldrich， CAS # 7647-14-5） 和 KCl （Sigma-Aldrich， CAS # 7447-40-7） 作为熔盐。在典型程序中，将 Ti 3 AlC 2 按以下比例（Ti 3 AlC 2 ：CuCl 2 ：NaCl：KCl = 1：3：2：2 摩尔比）与熔盐混合，并在空气中充分研磨 10 分钟，以确保混合物均匀。然后在管式炉中，在流动的氩气下，以 4 °C/min 的加热速度将混合物加热至 680 °C，持续 24 小时。使用去离子水洗涤所得红棕色产物，并使用多孔阳极氧化铝膜过滤器（直径 47 mm，孔径 0.2 mm，Whatman Anodisc，Maidstone，UK）通过真空过滤收集。之后，制备 APS （（NH 4 ） 2 S 2 O，Sigma-Aldrich，CAS 8 # 7727-54-0）溶液并加入内部以进一步溶解残留的 Cu。最后，经去离子水清洗后，经真空过滤收集上述产物，然后在 80 °C 的真空烘箱中干燥过夜。
以 Ti 3 AlC 2 作为 MAX 相前驱体，选择 CuCl 2 （Sigma-Aldrich， CAS # 7447-39-4）、NaCl （Sigma-Aldrich， CAS # 7647-14-5） 和 KCl （Sigma-Aldrich， CAS # 7447-40-7） 作为熔盐。在典型程序中，将 Ti 3 AlC 2 按以下比例（Ti 3 AlC 2 ：CuCl 2 ：NaCl：KCl = 1：3：2：2 摩尔比）与熔盐混合，并在空气中充分研磨 10 分钟，以确保混合物均匀。然后在管式炉中，在流动的氩气下，以 4 °C/min 的加热速度将混合物加热至 680 °C，持续 24 小时。使用去离子水洗涤所得红棕色产物，并使用多孔阳极氧化铝膜过滤器（直径 47 mm，孔径 0.2 mm，Whatman Anodisc，Maidstone，UK）通过真空过滤收集。之后，制备 APS （（NH 4 ） 2 S 2 O，Sigma-Aldrich，CAS 8 # 7727-54-0）溶液并加入内部以进一步溶解残留的 Cu。最后，经去离子水清洗后，经真空过滤收集上述产物，然后在 80 °C 的真空烘箱中干燥过夜。
Exfoliation and Delamination of MS-MXenes
MS-MXenes 的剥离和分层
A 0.2 g amount of MS-Ti3C2Tx was added to 5 mL of an aqueous solution of TBAOH (40%) and 10 mL of deionized water under Ar gas and kept overnight under stirring at 40 °C in a water bath. The obtained colloidal MXene suspension was then centrifuged at 15 300 rpm with a large excess of water to totally separate the intercalated powder from the liquid TBAOH. Deionized water was subsequently added to the residue in a weight ratio of MXene to water of 1:500. Ultrasonication of the bath was carried out for 6 h at low temperature (ice) to limit oxidation. Then, the TBAOH-treated MS-MXenes were centrifuged at 3500 rpm for 30 min to eliminate the sediment. After the elimination of the precipitate, the MXene was dried via vacuum freeze-drying for 4 days. For delamination, the MS-Ti3C2Tx MXene was left in TMAOH for 72 h, in which 18 h were dedicated to sonication in an iced bath to avoid oxidation. The sonication was accomplished as a step-by-step process (6 h each day) and stored inside the freezer during the rest of the time. Following the sonication process, the solution was centrifuged at 15 300 rpm for 15 min to precipitate all particles, and the above TMAOH solution was removed by using a pipet. Finally, the delaminated MS-MXene was centrifuged at 7000 rpm for 8 min to eliminate the sediment. After the elimination of the precipitate, the delaminated MXene was collected by vacuum filtration.
在 Ar 气体下，将 0.2 g 的 MS-Ti 3 C 2 T x 添加到 5 mL TBAOH （40%） 水溶液和 10 mL 去离子水中，并在 40 °C 下在水浴中搅拌保存过夜。然后将获得的胶体 MXene 悬浮液以 15 300 rpm 的速度离心，加入大量过量的水，以将插层粉末与液体 TBAOH 完全分离。随后以 MXene 与水的重量比为 1：500 的重量比将去离子水添加到残留物中。在低温（冰）下对浴液进行超声处理 6 小时以限制氧化。然后，将 TBAOH 处理的 MS-MXenes 以 3500 rpm 离心 30 分钟以去除沉淀物。去除沉淀后，将 MXene 通过真空冷冻干燥干燥 4 天。对于分层，将 MS-Ti 3 C 2 T x MXene 在 TMAOH 中放置 72 小时，其中 18 小时专门用于在冰浴中超声处理以避免氧化。超声处理是一个循序渐进的过程（每天 6 小时），其余时间存放在冰箱内。超声处理后，将溶液以 15 300 rpm 离心 15 分钟以沉淀所有颗粒，并使用移液管除去上述 TMAOH 溶液。最后，将分层的 MS-MXene 以 7000 rpm 离心 8 min，以去除沉淀物。除去沉淀后，真空过滤收集分层的 MXene。
在 Ar 气体下，将 0.2 g 的 MS-Ti 3 C 2 T x 添加到 5 mL TBAOH （40%） 水溶液和 10 mL 去离子水中，并在 40 °C 下在水浴中搅拌保存过夜。然后将获得的胶体 MXene 悬浮液以 15 300 rpm 的速度离心，加入大量过量的水，以将插层粉末与液体 TBAOH 完全分离。随后以 MXene 与水的重量比为 1：500 的重量比将去离子水添加到残留物中。在低温（冰）下对浴液进行超声处理 6 小时以限制氧化。然后，将 TBAOH 处理的 MS-MXenes 以 3500 rpm 离心 30 分钟以去除沉淀物。去除沉淀后，将 MXene 通过真空冷冻干燥干燥 4 天。对于分层，将 MS-Ti 3 C 2 T x MXene 在 TMAOH 中放置 72 小时，其中 18 小时专门用于在冰浴中超声处理以避免氧化。超声处理是一个循序渐进的过程（每天 6 小时），其余时间存放在冰箱内。超声处理后，将溶液以 15 300 rpm 离心 15 分钟以沉淀所有颗粒，并使用移液管除去上述 TMAOH 溶液。最后，将分层的 MS-MXene 以 7000 rpm 离心 8 min，以去除沉淀物。除去沉淀后，真空过滤收集分层的 MXene。
Physical Characterizations
物理特性
XRD data were collected by a D4 Endeavor X-ray diffractometer (Bruker, Germany) equipped with Cu Kα radiation (λ = 0.154 nm). The morphology of the MXenes was observed with a JSM 7100F scanning electron microscope (SEM) (JEOL, Japan). TEM and HRTEM images were performed using a JEM-2100 F microscope working at an acceleration voltage of 200 kV. The zeta potential was measured using a Zetasizer Nano ZS90 (Malvern Instruments Ltd., UK, England). The pH for the solutions of MXenes in deionized (DI) water was adjusted using HCl and NaOH. At each pH value, 10 measurements were collected for the zeta potential and the mean value was reported. The WCA was measured via a contact angle meter (DSA30 drop shape analyzer from Kruss).
XRD 数据由配备 Cu Kα 辐射 （λ = 0.154 nm） 的 D4 Endeavor X 射线衍射仪（德国布鲁克）收集。使用 JSM 7100F 扫描电子显微镜 （SEM） （JEOL，日本） 观察 MXenes 的形态。TEM 和 HRTEM 图像是使用在 200 kV 加速电压下工作的 JEM-2100 F 显微镜进行的。使用 Zetasizer Nano ZS90（Malvern Instruments Ltd.，英国，英国）测量 zeta 电位。使用 HCl 和 NaOH 调节 MXenes 在去离子 （DI） 水中溶液的 pH 值。在每个 pH 值下，收集 10 次 zeta 电位测量值并报告平均值。WCA 是通过接触角仪（Kruss 的 DSA30 液滴形状分析仪）测量的。
XRD 数据由配备 Cu Kα 辐射 （λ = 0.154 nm） 的 D4 Endeavor X 射线衍射仪（德国布鲁克）收集。使用 JSM 7100F 扫描电子显微镜 （SEM） （JEOL，日本） 观察 MXenes 的形态。TEM 和 HRTEM 图像是使用在 200 kV 加速电压下工作的 JEM-2100 F 显微镜进行的。使用 Zetasizer Nano ZS90（Malvern Instruments Ltd.，英国，英国）测量 zeta 电位。使用 HCl 和 NaOH 调节 MXenes 在去离子 （DI） 水中溶液的 pH 值。在每个 pH 值下，收集 10 次 zeta 电位测量值并报告平均值。WCA 是通过接触角仪（Kruss 的 DSA30 液滴形状分析仪）测量的。
Electrochemical Measurements
电化学测量
MXene powders were processed into free-standing electrode films by mixing 80 wt % of MXene powders together with 15 wt % of carbon black and 5 wt % of PTFE binder, followed by vacuum drying for 1 day. The electrode mass loading was around 1.1 mg cm–2. Lithium metal foils were used as both counter and reference electrodes, and a Cu disk was used as working electrode current collector. The electrolyte was a commercial solution of LP30 (1 M LiPF6 in ethylene carbonate/dimethyl carbonate with 1:1 volume ratio), and two layers of 260-μm-thick porous glass fibers (Whatman GF/A) were used as the separator. Two-electrode Swagelok cells were assembled in an argon-filled glovebox (moisture <0.1 ppm, oxygen <0.1 ppm) to perform electrochemical measurements.
通过将 80 wt % 的 MXene 粉末与 15 wt % 的炭黑和 5 wt% 的 PTFE 粘合剂混合，然后真空干燥 1 天，将 MXene 粉末加工成独立的电极膜。电极质量负载约为 1.1 mg cm –2 。锂金属箔用作对电极和参比电极，Cu 盘用作工作电极集流体。电解质为 LP30 的商业溶液（1 M LiPF 6 在碳酸乙烯酯/碳酸二甲酯中，体积比为 1：1），并使用两层 260 μm 厚的多孔玻璃纤维 （Whatman GF/A） 作为隔膜。将双电极世伟洛克电池组装在充满氩气的手套箱（水分 <0.1 ppm，氧气 <0.1 ppm）中，以进行电化学测量。
通过将 80 wt % 的 MXene 粉末与 15 wt % 的炭黑和 5 wt% 的 PTFE 粘合剂混合，然后真空干燥 1 天，将 MXene 粉末加工成独立的电极膜。电极质量负载约为 1.1 mg cm –2 。锂金属箔用作对电极和参比电极，Cu 盘用作工作电极集流体。电解质为 LP30 的商业溶液（1 M LiPF 6 在碳酸乙烯酯/碳酸二甲酯中，体积比为 1：1），并使用两层 260 μm 厚的多孔玻璃纤维 （Whatman GF/A） 作为隔膜。将双电极世伟洛克电池组装在充满氩气的手套箱（水分 <0.1 ppm，氧气 <0.1 ppm）中，以进行电化学测量。
Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic cycling were performed using a VMP3 potentiostat (Biologic, France). Cyclic voltammetry and galvanostatic cycling was carried out within a potential range from 0.2 to 3 V vs Li/Li+. Electrochemical impedance spectroscopy was performed at open-circuit potential with a 10 mV amplitude between 10 mHz and 200 kHz.
使用 VMP3 恒电位仪 （Biologic， France） 进行循环伏安法、电化学阻抗谱和恒电流循环。循环伏安法和恒电流循环在 0.2 至 3 V vs Li/Li + 的电位范围内进行。电化学阻抗谱是在开路电位下进行的，振幅为 10 mV，介于 10 mHz 和 200 kHz 之间。
使用 VMP3 恒电位仪 （Biologic， France） 进行循环伏安法、电化学阻抗谱和恒电流循环。循环伏安法和恒电流循环在 0.2 至 3 V vs Li/Li + 的电位范围内进行。电化学阻抗谱是在开路电位下进行的，振幅为 10 mV，介于 10 mHz 和 200 kHz 之间。
Supporting Information 支持信息
Click to copy section link
单击以复制部分链接Section link copied!
单击以复制部分链接Section link copied!
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsnano.1c08498.
Additional experimental data such as EDS, TEM, and electrochemical properties of the pristine and TMAOH-treated MS-Ti3C2 MXenes (PDF)
其他实验数据，例如原始和 TMAOH 处理的 MS-Ti 3 C 2 MXenes 的 EDS、TEM 和电化学性质 （PDF）
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Author Information
Click to copy section linkSection link copied!
- Patrice Simon - CIRIMAT, UMR CNRS 5085, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse, France; RS2E, Réseau Français sur le Stockage Electrochimique de l’Energie, FR CNRS 3459, 80039 Amiens Cedex, France;
https://orcid.org/0000-0002-0461-8268;
Acknowledgments
Click to copy section linkSection link copied!
L.L. was supported by ERC Synergy Grant MoMa-Stor #951513. P.S. and P.L.T. acknowledge the support from Agence Nationale de la Recherche (Labex Store-ex) and ERC Synergy Grant MoMa-Stor #951513. M.O. was supported by the Mundus plus “MESC” Master program of the European Commission.
References
Click to copy section linkSection link copied!
This article references 32 other publications.
- 1Lukatskaya, M. R.; Mashtalir, O.; Ren, C. E.; Dall’Agnese, Y.; Rozier, P.; Taberna, P. L.; Naguib, M.; Simon, P.; Barsoum, M. W.; Gogotsi, Y. Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide. Science (Washington, DC, U. S.) 2013, 341 (6153), 1502– 1505, DOI: 10.1126/science.1241488Google Scholar1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFSmsLjO&md5=c700d741ed4085a1a8cb2cd6f3d30facCation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium CarbideLukatskaya, Maria R.; Mashtalir, Olha; Ren, Chang E.; Dall'Agnese, Yohan; Rozier, Patrick; Taberna, Pierre Louis; Naguib, Michael; Simon, Patrice; Barsoum, Michel W.; Gogotsi, YuryScience (Washington, DC, United States) (2013), 341 (6153), 1502-1505CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)The intercalation of ions into layered compds. has long been exploited in energy storage devices such as batteries and electrochem. capacitors. However, few host materials are known for ions much larger than lithium. We demonstrate the spontaneous intercalation of cations from aq. salt solns. between two-dimensional (2D) Ti3C2 MXene layers. MXenes combine 2D conductive carbide layers with a hydrophilic, primarily hydroxyl-terminated surface. A variety of cations, including Na+, K+, NH4+, Mg2+, and Al3+, can also be intercalated electrochem., offering capacitance in excess of 300 F per cubic centimeter (much higher than that of porous carbons). This study provides a basis for exploring a large family of 2D carbides and carbonitrides in electrochem. energy storage applications using single- and multivalent ions.
- 2Naguib, M.; Kurtoglu, M.; Presser, V.; Lu, J.; Niu, J.; Heon, M.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W. Two-Dimensional Nanocrystals Produced by Exfoliation of Ti 3AlC 2. Adv. Mater. 2011, 23 (37), 4248– 4253, DOI: 10.1002/adma.201102306Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGisLnL&md5=2c476f3f7f645d96680e0f4c9c3513e0Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2Naguib, Michael; Kurtoglu, Murat; Presser, Volker; Lu, Jun; Niu, Junjie; Heon, Min; Hultman, Lars; Gogotsi, Yury; Barsoum, Michel W.Advanced Materials (Weinheim, Germany) (2011), 23 (37), 4248-4253CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Treatment of Ti3AlC2 powders for 2 h in HF results in the formation of exfoliated 2-dimensional (2D) Ti3C2 layers (nanosheets). The Ti3AlC2 structure is composed of individual Ti3C2 layers sepd. by Al atoms. Upon reaction with HF, Al atoms are removed from between the layers, resulting in the exfoliation of individual Ti3C2 layers from each other due to the loss of metallic bonding holding them together when the Al atoms are present. The exposed 2D Ti3C2 layers possess 2 exposed Ti atoms per unit formula that should be satisfied by suitable ligands. Since the expts. were conducted in an aq. environment rich in F ions, hydroxyl and F are the most probable ligands. Modeling of each case was conduced by attaching resp. ligands to the exposed Ti atoms followed by full geometry optimizations. The exposed Ti surfaces appear to be terminated by OH and/or F. The large elastic moduli predicted by ab initio simulation, and the possibility of varying their surface chem. render these nanosheets attractive as polymer composite fillers. The implications and importance of this work extend far beyond the results shown herein. There are over 60 currently known MAX phases; therefore, this work, in principle, opens the door for formation of a large no. of 2D Mn+1Xn structures, including the carbides and nitrides of Ti, V, Cr, Nb, Ta, Hf, and Zr. The latter could include 2D structures of combination of M-atoms, e.g., Ti0.5Zr0.5InC and/or different combinations of C and N, such as Ti2AlC0.5N0.5, if the selective chem. etching is extended to other MAX phases. We currently have solid evidence for the exfoliation of Ta4AlC3 into Ta4C3 flakes.
- 3Wang, X.; Mathis, T. S.; Li, K.; Lin, Z.; Vlcek, L.; Torita, T.; Osti, N. C.; Hatter, C.; Urbankowski, P.; Sarycheva, A.; Tyagi, M.; Mamontov, E.; Simon, P.; Gogotsi, Y. Influences from Solvents on Charge Storage in Titanium Carbide MXenes. Nat. Energy 2019, 4 (3), 241– 248, DOI: 10.1038/s41560-019-0339-9Google Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXmslKjurw%253D&md5=8ab785d740429399dee7cc50ec0e3e00Influences from solvents on charge storage in titanium carbide MXenesWang, Xuehang; Mathis, Tyler S.; Li, Ke; Lin, Zifeng; Vlcek, Lukas; Torita, Takeshi; Osti, Naresh C.; Hatter, Christine; Urbankowski, Patrick; Sarycheva, Asia; Tyagi, Madhusudan; Mamontov, Eugene; Simon, Patrice; Gogotsi, YuryNature Energy (2019), 4 (3), 241-248CODEN: NEANFD; ISSN:2058-7546. (Nature Research)Pseudocapacitive energy storage in supercapacitor electrodes differs significantly from the elec. double-layer mechanism of porous carbon materials, which requires a change from conventional thinking when choosing appropriate electrolytes. Here we show how simply changing the solvent of an electrolyte system can drastically influence the pseudocapacitive charge storage of the two-dimensional titanium carbide, Ti3C2 (a representative member of the MXene family). Measurements of the charge stored by Ti3C2 in lithium-contg. electrolytes with nitrile-, carbonate- and sulfoxide-based solvents show that the use of a carbonate solvent doubles the charge stored by Ti3C2 when compared with the other solvent systems. We find that the chem. nature of the electrolyte solvent has a profound effect on the arrangement of mols./ions in Ti3C2, which correlates directly to the total charge being stored. Having nearly completely desolvated lithium ions in Ti3C2 for the carbonate-based electrolyte leads to high volumetric capacitance at high charge-discharge rates, demonstrating the importance of considering all aspects of an electrochem. system during development.
- 4Beda, A.; Taberna, P. L.; Simon, P.; Matei Ghimbeu, C. Hard Carbons Derived from Green Phenolic Resins for Na-Ion Batteries. Carbon 2018, 139, 248– 257, DOI: 10.1016/j.carbon.2018.06.036Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXht1GmsLrK&md5=11d925e13b5904589cee1f65b1e20779Hard carbons derived from green phenolic resins for Na-ion batteriesBeda, Adrian; Taberna, Pierre-Louis; Simon, Patrice; Matei Ghimbeu, CameliaCarbon (2018), 139 (), 248-257CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)Hard carbons have become recently one of the most promising classes of anode materials for Na ion batteries (NIBs) owing to their high specific capacity and good cycling stability. Among the precursors used to prep. hard C, phenolic resins are of great interest due to their high C yield, however, their toxicity must be overcome. The authors propose a green, simple and scalable procedure to obtain phenolic resins which by pyrolysis at high temp. (>1000°) result in eco-friendly hard carbons with low surface area, disordered structure and high C yield. The influence of several synthesis parameters (type of solvent, thermopolymn./annealing temp. and gas flow) was studied to det. the impact on both phenolic resin and hard C characteristics. The synthesis time (12 h-3 days) depends on the used solvent whereas the C yield (25-35%) on the crosslinking degree which could be controlled by adjusting both thermopolymn. temp. and atm. The structure of the hard carbons mainly changed with the carbonization temp. (1100-1700°) while the texture of the material was sensitive to most of the studied parameters. Stable reversible capacity up to 270 mA h g-1 and 100% coulombic efficiency (CE) after few cycles are obtained, demonstrating the potential for Na-ion applications.
- 5Lukatskaya, M. R.; Kota, S.; Lin, Z.; Zhao, M. Q.; Shpigel, N.; Levi, M. D.; Halim, J.; Taberna, P. L.; Barsoum, M. W.; Simon, P.; Gogotsi, Y. Ultra-High-Rate Pseudocapacitive Energy Storage in Two-Dimensional Transition Metal Carbides. Nat. Energy 2017, 6 (July), 1– 6, DOI: 10.1038/nenergy.2017.105Google ScholarThere is no corresponding record for this reference.
- 6Simon, P. Two-Dimensional MXene with Controlled Interlayer Spacing for Electrochemical Energy Storage. ACS Nano 2017, 11 (3), 2393– 2396, DOI: 10.1021/acsnano.7b01108Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjvFygtrs%253D&md5=cf1962337f1b6cfbd37e344b0bead0a9Two-Dimensional MXene with Controlled Interlayer Spacing for Electrochemical Energy StorageSimon, PatriceACS Nano (2017), 11 (3), 2393-2396CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review is presented. In this issue of ACS Nano, Luo et al. report the prepn. of pillared two-dimensional (2D) Ti3C2 MXenes with controllable interlayer spacings between 1 and 2.708 nm. These materials were further intercalated by ion exchange with Sn(+IV) ions. The results show improved electrochem. performance due to improved ion accessibility into the 2D structure as well as the confinement effect, which limits vol. expansion during the Li-alloying reaction. Beyond this specific example, the demonstration that the interlayer spacings of MXenes can be fine-tuned by creating pillared structures based on the spontaneous intercalation of surfactants opens new perspectives in the field of electrochem. energy storage.
- 7Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y. 2D Metal Carbides and Nitrides (MXenes) for Energy Storage. Nat. Rev. Mater. 2017, 2 (2), DOI: 10.1038/natrevmats.2016.98 .Google ScholarThere is no corresponding record for this reference.
- 8Hu, M.; Hu, T.; Li, Z.; Yang, Y.; Cheng, R.; Yang, J.; Cui, C.; Wang, X. Surface Functional Groups and Interlayer Water Determine the Electrochemical Capacitance of Ti3C2 T x MXene. ACS Nano 2018, 12 (4), 3578– 3586, DOI: 10.1021/acsnano.8b00676Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXmvVaru74%253D&md5=25f8b2c699e45197ee6b1f92c61a8b88Surface Functional Groups and Interlayer Water Determine the Electrochemical Capacitance of Ti3C2Tx MXeneHu, Minmin; Hu, Tao; Li, Zhaojin; Yang, Yi; Cheng, Renfei; Yang, Jinxing; Cui, Cong; Wang, XiaohuiACS Nano (2018), 12 (4), 3578-3586CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)MXenes, an emerging class of conductive two-dimensional materials, have been regarded as promising candidates in the field of electrochem. energy storage. The electrochem. performance of their representative Ti3C2Tx, where T represents the surface termination group of F, O, or OH, strongly relies on termination-mediated surface functionalization, but an in-depth understanding of the relationship between them remains unresolved. Here, we studied comprehensively the structural feature and electrochem. performance of two kinds of Ti3C2Tx MXenes obtained by etching the Ti3AlC2 precursor in aq. HF soln. at low concn. (6 mol/L) and high concn. of (15 mol/L). A significantly higher capacitance was recognized in a low-concn. HF-etched MXene (Ti3C2Tx-6M) electrode. In situ Raman spectroscopy and XPS demonstrate that Ti3C2Tx-6M has more components of the -O functional group. In combination with X-ray diffraction anal., low-field 1H NMR spectroscopy in terms of relaxation time unambiguously underlines that Ti3C2Tx-6M is capable of accommodating more high-mobility H2O mols. between the Ti3C2Tx interlayers, enabling more hydrogen ions to be more readily accessible to the active sites of Ti3C2Tx-6M. The two main key factors (i.e., high content of -O functional groups that are involved bonding/debonding-induced pseudocapacitance and more high-mobility water intercalated between the MXene interlayers) simultaneously account for the superior capacitance of the Ti3C2Tx-6M electrode. This study provides a guideline for the rational design and construction of high-capacitance MXene and MXene-based hybrid electrodes in aq. electrolytes.
- 9Moitzheim, S.; De Gendt, S.; Vereecken, P. M. Investigation of the Li-Ion Insertion Mechanism for Amorphous and Anatase TiO 2 Thin-Films. J. Electrochem. Soc. 2019, 166 (2), A1– A9, DOI: 10.1149/2.1091816jesGoogle Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXotVWlsrc%253D&md5=2e5297b1b3beead168d6a408a35afd03Investigation of the Li-ion insertion mechanism for amorphous and anatase TiO2 Thin-FilmsMoitzheim, S.; Gendt, S. De; Vereecken, P. M.Journal of the Electrochemical Society (2019), 166 (2), A1-A9CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)Titania is considered an interesting anode candidate for Li+-ion batteries, as it offers a high theor. capacity (1280 mAh cm-3 or 336 mAh g-1) and long term cycling stability. Unfortunately, the most commonly investigated anatase structure never reaches the theor. capacity at practical charging rates (i.e. above 1 C). In this work, we compare amorphous (am-TiO2) to anatase TiO2 thin-films, and investigate the exceptional performance of am-TiO2 as Li+-ion insertion electrode. An in-depth electrochem. characterization using cyclic voltammetry (CV), const. current lithiation and delithiation, and potentiostatic intermittent titrn. technique (PITT) is performed. From CV, the insertion and extn. kinetics of am-TiO2 is unrestricted by diffusion, contrary to anatase. Based on our combined electrochem. results, two different mechanisms are formulated for anatase and am- TiO2. Whereas anatase is filled from the "top-down", with a buildup of Li near the electrode/electrolyte interface, am-TiO2 shows a "bottom-up" filling mechanism. This discrepancy is ascribed to the difference in diffusion coeff. measured for am-TiO2 and anatase. This work highlights the differences of Li-ion insertion into amorphous TiO2 compared to anatase, and gives guidance on material development for high capacity and fast charging electrodes.
- 10Ghidiu, M.; Lukatskaya, M. R.; Zhao, M. Q.; Gogotsi, Y.; Barsoum, M. W. Conductive Two-Dimensional Titanium Carbide “Clay” with High Volumetric Capacitance. Nature 2014, 516 (7529), 78– 81, DOI: 10.1038/nature13970Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVakt7zN&md5=ac29b037ec6f81f7b64dd05b878bf626Conductive two-dimensional titanium carbide 'clay' with high volumetric capacitanceGhidiu, Michael; Lukatskaya, Maria R.; Zhao, Meng-Qiang; Gogotsi, Yury; Barsoum, Michel W.Nature (London, United Kingdom) (2014), 516 (7529), 78-81CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)A conductive two-dimensional titanium carbide material (called "clay" because of its maleability and "shapeability") with a high volumetric capacitance is prepd. by etching titanium carbide (Ti3AlC2) with a soln. of LiF in concd. HCl. The resulting sediment (of general formula Ti3C2T, in which T denotes surface functionality) is a hydrophilic material that undergoes swelling when hydrated, and can be shaped like clay and dried into a highly conductive solid or rolled into films tens of micrometers thick. Additive-free films of this titanium carbide "clay" have volumetric capacitances of up to 900 F per cm3, and has excellent cyclability and rate performance. The prepn. method avoids the hazards of handling concd. hydrofluoric acid.
- 11Feng, A.; Yu, Y.; Jiang, F.; Wang, Y.; Mi, L.; Yu, Y.; Song, L. Fabrication and Thermal Stability of NH4HF2-Etched Ti3C2MXene. Ceram. Int. 2017, 43 (8), 6322– 6328, DOI: 10.1016/j.ceramint.2017.02.039Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXis1Sjsrg%253D&md5=40e5c0733421dea5e3885cce94de37caFabrication and thermal stability of NH4HF2-etched Ti3C2 MXeneFeng, Aihu; Yu, Yun; Jiang, Feng; Wang, Yong; Mi, Le; Yu, Yang; Song, LixinCeramics International (2017), 43 (8), 6322-6328CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)MXene, a new family of 2D transition metal carbides and carbonitrides, has been proved to possess excellent elec. cond. and hydrophilicity. In this work, a single-step method to produce the larger interplanar spacing 2D MXene Ti3C2 by etching Ti3AlC2 with NH4HF2 was demonstrated, and the optimal reaction conditions between Ti3AlC2 and NH4HF2 were systematically researched. The morphol. and microstructure of samples were characterized by SEM (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). The thermal stability of Ti3C2 was investigated by the thermogravimetry (TG) and differential thermal analyzer (DTA). It was found that the lattice parameter c of obtained Ti3C2 was up to 24.9 Å, and the larger interplanar spacing Ti3C2 was more stable than the sample exfoliated by HF. The transition temp. in air from NH4HF2-etched Ti3C2 to anatase TiO2 thoroughly is more than 500°C, and the multilayered structure of Ti3C2 could be well retained even after 900°C heat treatment, while the value of HF-etched Ti3C2 is less than 350°C. This work is important for exploring a safe synthesis method and well understanding the thermal stability of 2D MXene materials.
- 12Li, M.; Lu, J.; Luo, K.; Li, Y.; Chang, K.; Chen, K.; Zhou, J.; Rosen, J.; Hultman, L.; Eklund, P.; Persson, P.; Du, S.; Chai, Z.; Huang, Z.; Huang, Q. Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes. J. Am. Chem. Soc. 2019, 141 (11), 4730– 4737, DOI: 10.1021/jacs.9b00574Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXktVCiu7w%253D&md5=29c378a685955409963f771851acb591Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenesLi, Mian; Lu, Jun; Luo, Kan; Li, Youbing; Chang, Keke; Chen, Ke; Zhou, Jie; Rosen, Johanna; Hultman, Lars; Eklund, Per; Persson, Per O. A.; Du, Shiyu; Chai, Zhifang; Huang, Zhengren; Huang, QingJournal of the American Chemical Society (2019), 141 (11), 4730-4737CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesizing a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition-metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between the Zn element from molten ZnCl2 and the Al element in MAX phase precursors (Ti3AlC2, Ti2AlC, Ti2AlN, and V2AlC), novel MAX phases Ti3ZnC2, Ti2ZnC, Ti2ZnN, and V2ZnC were synthesized. When employing excess ZnCl2, Cl-terminated MXenes (such as Ti3C2Cl2 and Ti2CCl2) were derived by a subsequent exfoliation of Ti3ZnC2 and Ti2ZnC due to the strong Lewis acidity of molten ZnCl2. A-site element replacement in traditional MAX phases by late transition-metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temp. and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addn., this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to prepg. MXenes through an HF-free chem. approach.
- 13Li, Y.; Shao, H.; Lin, Z.; Lu, J.; Liu, L.; Duployer, B.; Persson, P. O. Å.; Eklund, P.; Hultman, L.; Li, M.; Chen, K.; Zha, X.; Du, S.; Rozier, P.; Chai, Z.; Raymundo-Piñero, E.; Taberna, P. L.; Simon, P.; Huang, Q. A General Lewis Acidic Etching Route for Preparing MXenes with Enhanced Electrochemical Performance in Non-Aqueous Electrolyte. Nat. Mater. 2020, 19 (8), 894– 899, DOI: 10.1038/s41563-020-0657-0Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXmvFylsrs%253D&md5=4b3f9d9b2c467a77dce144c51a394322A general Lewis acidic etching route for preparing MXenes with enhanced electrochemical performance in non-aqueous electrolyteLi, Youbing; Shao, Hui; Lin, Zifeng; Lu, Jun; Liu, Liyuan; Duployer, Benjamin; Persson, Per O. A.; Eklund, Per; Hultman, Lars; Li, Mian; Chen, Ke; Zha, Xian-Hu; Du, Shiyu; Rozier, Patrick; Chai, Zhifang; Raymundo-Pinero, Encarnacion; Taberna, Pierre-Louis; Simon, Patrice; Huang, QingNature Materials (2020), 19 (8), 894-899CODEN: NMAACR; ISSN:1476-1122. (Nature Research)Two-dimensional carbides and nitrides of transition metals, known as MXenes, are a fast-growing family of materials that have attracted attention as energy storage materials. MXenes are mainly prepd. from Al-contg. MAX phases (where A = Al) by Al dissoln. in F-contg. soln.; most other MAX phases have not been explored. Here a redox-controlled A-site etching of MAX phases in Lewis acidic melts is proposed and validated by the synthesis of various MXenes from unconventional MAX-phase precursors with A elements Si, Zn, and Ga. A neg. electrode of Ti3C2 MXene material obtained through this molten salt synthesis method delivers a Li+ storage capacity of ≤ 738 C g-1 (205 mAh g-1) with high charge-discharge rate and a pseudocapacitive-like electrochem. signature in 1 M LiPF6 carbonate-based electrolyte. MXenes prepd. via this molten salt synthesis route may prove suitable for use as high-rate neg.-electrode materials for electrochem. energy storage applications.
- 14Kamysbayev, V.; Filatov, A. S.; Hu, H.; Rui, X.; Lagunas, F.; Wang, D.; Klie, R. F.; Talapin, D. V. Covalent Surface Modifications and Superconductivity of Two-Dimensional Metal Carbide MXenes. Science (Washington, DC, U. S.) 2020, 369 (6506), 979– 983, DOI: 10.1126/science.aba8311Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1GrsbzL&md5=e353a4299a9744b88bd512bd5969a528Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenesKamysbayev, Vladislav; Filatov, Alexander S.; Hu, Huicheng; Rui, Xue; Lagunas, Francisco; Wang, Di; Klie, Robert F.; Talapin, Dmitri V.Science (Washington, DC, United States) (2020), 369 (6506), 979-983CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)Versatile chem. transformations of surface functional groups in two-dimensional transition-metal carbides (MXenes) open up a previously unexplored design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorg. salts. Successful synthesis of MXenes with oxygen, imido, sulfur, chlorine, selenium, bromine, and tellurium surface terminations, as well as bare MXenes (no surface termination), was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interat. distances in the MXene lattice, and Tin+1Cn (n = 1, 2) MXenes terminated with telluride (Te2-) ligands show a giant (>18%) in-plane lattice expansion compared with the unstrained titanium carbide lattice. The surface groups also control supercond. of niobium carbide MXenes.
- 15Li, M.; Li, X.; Qin, G.; Luo, K.; Lu, J.; Li, Y.; Liang, G.; Huang, Z.; Zhou, J.; Hultman, L.; Eklund, P.; Persson, P.O. Å.; Du, S.; Chai, Z.; Zhi, C.; Huang, Q. Halogenated Ti3C2MXenes with Electrochemically Active Terminals for High-Performance Zinc Ion Batteries. ACS Nano 2021, 15 (1), 1077– 1085, DOI: 10.1021/acsnano.0c07972Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmtFykuw%253D%253D&md5=15e37cc12243369ff321efb594e0816fHalogenated Ti3C2 MXenes with Electrochemically Active Terminals for High-Performance Zinc Ion BatteriesLi, Mian; Li, Xinliang; Qin, Guifang; Luo, Kan; Lu, Jun; Li, Youbing; Liang, Guojin; Huang, Zhaodong; Zhou, Jie; Hultman, Lars; Eklund, Per; Persson, Per O. A.; Du, Shiyu; Chai, Zhifang; Zhi, Chunyi; Huang, QingACS Nano (2021), 15 (1), 1077-1085CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The class of two-dimensional metal carbides and nitrides known as MXenes offer a distinct manner of property tailoring for a wide range of applications. The ability to tune the surface chem. for expanding the property space of MXenes is thus an important topic, although exptl. exploration of surface terminals remains a challenge. Here, we synthesized Ti3C2 MXene with unitary, binary, and ternary halogen terminals, e.g., -Cl, -Br, -I, -BrI, and -ClBrI, to investigate the effect of surface chem. on the properties of MXenes. The electrochem. activity of Br and I elements results in the extraordinary electrochem. performance of the MXenes as cathodes for aq. zinc ion batteries. The -Br- and -I-contg. MXenes, e.g., Ti3C2Br2 and Ti3C2I2, exhibit distinct discharge platforms with considerable capacities of 97.6 and 135 mAh·g-1. Ti3C2(BrI) and Ti3C2(ClBrI) exhibit dual discharge platforms with capacities of 117.2 and 106.7 mAh·g-1. In contrast, the previously discovered MXenes Ti3C2Cl2 and Ti3C2(OF) exhibit no discharge platforms and only ~ 50% of capacities and energy densities of Ti3C2Br2. These results emphasize the effectiveness of the Lewis-acidic-melt etching route for tuning the surface chem. of MXenes and also show promise for expanding the MXene family toward various applications.
- 16Mashtalir, O.; Naguib, M.; Mochalin, V. N.; Dall’Agnese, Y.; Heon, M.; Barsoum, M. W.; Gogotsi, Y. Intercalation and Delamination of Layered Carbides and Carbonitrides. Nat. Commun. 2013, 4, 1– 7, DOI: 10.1038/ncomms2664Google ScholarThere is no corresponding record for this reference.
- 17Alhabeb, M.; Maleski, K.; Anasori, B.; Lelyukh, P.; Clark, L.; Sin, S.; Gogotsi, Y. Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide (Ti3C2Tx MXene). Chem. Mater. 2017, 29 (18), 7633– 7644, DOI: 10.1021/acs.chemmater.7b02847Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtlyhsLjN&md5=768044a456d251660fa0120ea6cf8557Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide (Ti3C2Tx MXene)Alhabeb, Mohamed; Maleski, Kathleen; Anasori, Babak; Lelyukh, Pavel; Clark, Leah; Sin, Saleesha; Gogotsi, YuryChemistry of Materials (2017), 29 (18), 7633-7644CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXenes) were discovered in 2011. Since the original discovery, >20 different compns. have been synthesized by the selective etching of MAX phase and other precursors and many more theor. predicted. They offer a variety of different properties, making the family promising candidates in a wide range of applications, such as energy storage, electromagnetic interference shielding, water purifn., electrocatalysis, and medicine. These soln.-processable materials have the potential to be highly scalable, deposited by spin, spray, or dip coating, painted or printed, or fabricated in a variety of ways. Due to this promise, the amt. of research on MXenes has been increasing, and methods of synthesis and processing are expanding quickly. The fast evolution of the material can also be noticed in the wide range of synthesis and processing protocols that det. the yield of delamination, as well as the quality of the 2D flakes produced. Here we describe the exptl. methods and best practices we use to synthesize the most studied MXene, titanium carbide (Ti3C2Tx), using different etchants and delamination methods. We also explain effects of synthesis parameters on the size and quality of Ti3C2Tx and suggest the optimal processes for the desired application.
- 18Mashtalir, O.; Lukatskaya, M. R.; Zhao, M. Q.; Barsoum, M. W.; Gogotsi, Y. Amine-Assisted Delamination of Nb2C MXene for Li-Ion Energy Storage Devices. Adv. Mater. 2015, 27 (23), 3501– 3506, DOI: 10.1002/adma.201500604Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnsFCltrs%253D&md5=ccb60c8d992d93a495989af04a405d86Amine-Assisted Delamination of Nb2C MXene for Li-Ion Energy Storage DevicesMashtalir, Olha; Lukatskaya, Maria R.; Zhao, Meng-Qiang; Barsoum, Michel W.; Gogotsi, YuryAdvanced Materials (Weinheim, Germany) (2015), 27 (23), 3501-3506CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)MXenes are stacks of 2D early transition metal carbides and carbonitrides of general formula Mn+1XnTx , where M stands for metal atom, X stands for C and/or N, n = 1, 2, or 3, and Tx represents various surface terminations (OH, O, and/or F groups). Delaminated MXenes can store more charge than their multilayer counterparts; introduction of carbon additives, such as carbon nanotubes (CNTs) into the electrode structure improves ion accessibility to the MXene layers and boosts both specific capacities and resulting rate performances. So far only Ti3C2Tx has been synthesized and tested in delaminated form. To delaminate the latter DMSO, DMSO, was used. In this Communication, our main goal is to report on the delamination of a second representative of the MXene family Nb2CTx using an amine instead of DMSO. The electrochem. behavior of delaminated Nb2CTx/CNT composite electrodes in Li-ion batteries and supercapacitors are superior to their multilayered counterparts.
- 19Naguib, M.; Unocic, R. R.; Armstrong, B. L.; Nanda, J. Large-Scale Delamination of Multi-Layers Transition Metal Carbides and Carbonitrides “MXenes.. Dalt. Trans. 2015, 44 (20), 9353– 9358, DOI: 10.1039/C5DT01247CGoogle Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXms1ygu7w%253D&md5=d9a88c056f39d4c0ef9a0921d58b6dacLarge-scale delamination of multi-layers transition metal carbides and carbonitrides "MXenes"Naguib, Michael; Unocic, Raymond R.; Armstrong, Beth L.; Nanda, JagjitDalton Transactions (2015), 44 (20), 9353-9358CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Herein we report on a general approach to delaminate multi-layered MXenes using an org. base to induce swelling that in turn weakens the bonds between the MX layers. Simple agitation or mild sonication of the swollen MXene in water resulted in the large-scale delamination of the MXene layers. The delamination method is demonstrated for vanadium carbide and titanium carbonitride MXenes.
- 20Holder, C. F.; Schaak, R. E. Tutorial on Powder X-Ray Diffraction for Characterizing Nanoscale Materials. ACS Nano 2019, 13 (7), 7359– 7365, DOI: 10.1021/acsnano.9b05157Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtl2iu7%252FN&md5=1cc19bb0dce3776f4aefcb3eee6a308bTutorial on Powder X-ray Diffraction for Characterizing Nanoscale MaterialsHolder, Cameron F.; Schaak, Raymond E.ACS Nano (2019), 13 (7), 7359-7365CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review. The authors provide the broad nanoscience and nanotechnol. communities with a brief tutorial on some of the key aspects of powder XRD data that are often encountered when analyzing samples of nanoscale materials, with an emphasis on inorg. nanoparticles of various sizes, shapes, and dimensionalities.
- 21Ahmed, B.; Anjum, D. H.; Hedhili, M. N.; Gogotsi, Y.; Alshareef, H. N. H2O2 Assisted Room Temperature Oxidation of Ti2C MXene for Li-Ion Battery Anodes. Nanoscale 2016, 8 (14), 7580– 7587, DOI: 10.1039/C6NR00002AGoogle Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XjslKiur4%253D&md5=657228c1d37c6ff8c631b85e1113b98aH2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodesAhmed, Bilal; Anjum, Dalaver H.; Hedhili, Mohamed N.; Gogotsi, Yury; Alshareef, Husam N.Nanoscale (2016), 8 (14), 7580-7587CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidn. at room temp. when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) anal. We show that the reaction time and the amt. of hydrogen peroxide used are the limiting factors, which det. the morphol. and compn. of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepd. MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g-1, 337 mA h g-1 and 297 mA h g-1 were obtained for H2O2 treated MXene at current densities of 100 mA g-1, 500 mA g-1 and 1000 mA g-1, resp. In addn., when tested at a very high c.d., such as 5000 mA g-1, the H2O2 treated MXene showed a specific capacity of 150 mA h g-1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.
- 22Yuen, A. C. Y.; Chen, T. B. Y.; Lin, B.; Yang, W.; Kabir, I. I.; De Cachinho Cordeiro, I. M.; Whitten, A. E.; Mata, J.; Yu, B.; Lu, H. D.; Yeoh, G. H. Study of Structure Morphology and Layer Thickness of Ti3C2MXene with Small-Angle Neutron Scattering (SANS). Compos. Part C Open Access 2021, 5 (May), 100155, DOI: 10.1016/j.jcomc.2021.100155Google ScholarThere is no corresponding record for this reference.
- 23Lipatov, A.; Lu, H.; Alhabeb, M.; Anasori, B.; Gruverman, A.; Gogotsi, Y.; Sinitskii, A. Elastic Properties of 2D Ti3C2Tx MXene Monolayers and Bilayers. Sci. Adv. 2018, 4 (6), 1– 8, DOI: 10.1126/sciadv.aat0491Google ScholarThere is no corresponding record for this reference.
- 24Birkl, C. R.; Roberts, M. R.; McTurk, E.; Bruce, P. G.; Howey, D. A. Degradation Diagnostics for Lithium Ion Cells. J. Power Sources 2017, 341, 373– 386, DOI: 10.1016/j.jpowsour.2016.12.011Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVKrs7rI&md5=9ceba52b3288d990c89f44dd5c2405afDegradation diagnostics for lithium ion cellsBirkl, Christoph R.; Roberts, Matthew R.; McTurk, Euan; Bruce, Peter G.; Howey, David A.Journal of Power Sources (2017), 341 (), 373-386CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)Degrdn. in lithium ion (Li-ion) battery cells is the result of a complex interplay of a host of different phys. and chem. mechanisms. The measurable, phys. effects of these degrdn. mechanisms on the cell can be summarised in terms of three degrdn. modes, namely loss of lithium inventory, loss of active pos. electrode material and loss of active neg. electrode material. The different degrdn. modes are assumed to have unique and measurable effects on the open circuit voltage (OCV) of Li-ion cells and electrodes. The presumptive nature and extent of these effects has so far been based on logical arguments rather than exptl. proof. This work presents, for the first time, exptl. evidence supporting the widely reported degrdn. modes by means of tests conducted on coin cells, engineered to include different, known amts. of lithium inventory and active electrode material. Moreover, the general theory behind the effects of degrdn. modes on the OCV of cells and electrodes is refined and a diagnostic algorithm is devised, which allows the identification and quantification of the nature and extent of each degrdn. mode in Li-ion cells at any point in their service lives, by fitting the cells' OCV.
- 25Kong, F.; He, X.; Liu, Q.; Qi, X.; Zheng, Y.; Wang, R.; Bai, Y. Improving the Electrochemical Properties of MXene Ti3C2Multilayer for Li-Ion Batteries by Vacuum Calcination. Electrochim. Acta 2018, 265, 140– 150, DOI: 10.1016/j.electacta.2018.01.196Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVOqtLo%253D&md5=0d8c62eeed5a88a742709abc93b29247Improving the electrochemical properties of MXene Ti3C2 multilayer for Li-ion batteries by vacuum calcinationKong, Fanyu; He, Xiaodong; Liu, Qianqian; Qi, Xinxin; Zheng, Yongting; Wang, Rongguo; Bai, YueleiElectrochimica Acta (2018), 265 (), 140-150CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Ltd.)The electrochem. properties of MXene Ti3C2 multilayer for Li-ion batteries were improved greatly by vacuum calcination, after systematically evaluating its thermal stability in different atm. in details. In air, the as-prepd. Ti3C2 could not be oxidized up to 429.9° and the rutile-TiO2 would remain as the oxidn. product at 1200°. The surface functional groups esp. F groups can be eliminated by heat treatment. After vacuum calcination at 400°, the Ti3C2 show much higher capacities due to the removal of OH groups (126.4 mAh g-1 at 1C), and exhibited excellent rate capability. Besides, the formation of TiO2 nanoparticles at 700° further increases the 1st coulombic efficiency (62%) and capacity retention after 100 cycles (97%). In contrast, the dense microstructures of resulting TiCx formed after calcination at 1000° results in the worst electrochem. properties. This paper presented a relatively simple and easily scalable post-treatment for improving the electrochem. properties of MXene, and demonstrated a great potential of Ti3C2 of using as anode material for Li-ion batteries.
- 26Lv, G.; Wang, J.; Shi, Z.; Fan, L. Intercalation and Delamination of Two-Dimensional MXene (Ti3C2Tx) and Application in Sodium-Ion Batteries. Mater. Lett. 2018, 219, 45– 50, DOI: 10.1016/j.matlet.2018.02.016Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtVCku70%253D&md5=0bb2edd37b1c9c9fae0e76dd875a689fIntercalation and delamination of two-dimensional MXene (Ti3C2Tx) and application in sodium-ion batteriesLv, Guoxia; Wang, Jing; Shi, Zhiqiang; Fan, LipingMaterials Letters (2018), 219 (), 45-50CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The initial multilayer-structure two-dimensional transition metal carbide MXene (as-Ti3C2Tx) were synthesized by selectively etching Mn+1AXn in HF, and the surface of MXene adhere to some functional groups. Intercalation and delamination by ultrasonication in alc. or DMSO produce less lamellar structure of resultant (d-Ti3C2Tx) and change the surface circumstance. This fabricated fewer-sheets samples not only improve the elec. conductibility, specific area, but also reduce the ion diffusion resistance. Meanwhile, the d-aTi3C2Tx and d-D-Ti3C2Tx show outstanding capacity of 110 or 120 mAh g-1 at 100 mA g-1 with coulombic efficiency of ∼95%, which lead to 26% increase compared with as-Ti3C2Tx (95 mAh g-1) for Na-ion batteries, and remarkable capacitance retention of 84.5% or 85.8% after cycles for in alc. and DMSO, resp.
- 27Xie, Y.; Naguib, M.; Mochalin, V. N.; Barsoum, M. W.; Gogotsi, Y.; Yu, X.; Nam, K. W.; Yang, X. Q.; Kolesnikov, A. I.; Kent, P. R. C. Role of Surface Structure on Li-Ion Energy Storage Capacity of Two-Dimensional Transition-Metal Carbides. J. Am. Chem. Soc. 2014, 136 (17), 6385– 6394, DOI: 10.1021/ja501520bGoogle Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXltFGlsbk%253D&md5=8a48485460db1c614d1ec6741da1120fRole of surface structure on Li-ion energy storage capacity of two-dimensional transition-metal carbidesXie, Yu; Naguib, Michael; Mochalin, Vadym N.; Barsoum, Michel W.; Gogotsi, Yury; Yu, Xiqian; Nam, Kyung-Wan; Yang, Xiao-Qing; Kolesnikov, Alexander I.; Kent, Paul R. C.Journal of the American Chemical Society (2014), 136 (17), 6385-6394CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A combination of d. functional theory (DFT) calcns. and expts. is used to shed light on the relation between surface structure and Li-ion storage capacities of the following functionalized two-dimensional (2D) transition-metal carbides or MXenes: Sc2C, Ti2C, Ti3C2, V2C, Cr2C, and Nb2C. The Li-ion storage capacities are found to strongly depend on the nature of the surface functional groups, with O groups exhibiting the highest theor. Li-ion storage capacities. MXene surfaces can be initially covered with OH groups, removable by high-temp. treatment or by reactions in the first lithiation cycle. This was verified by annealing f-Nb2C and f-Ti3C2 at 673 and 773 K in vacuum for 40 h and in situ X-ray adsorption spectroscopy (XAS) and Li capacity measurements for the first lithiation/delithiation cycle of f-Ti3C2. The high-temp. removal of water and OH was confirmed using X-ray diffraction and inelastic neutron scattering. The voltage profile and X-ray adsorption near edge structure of f-Ti3C2 revealed surface reactions in the first lithiation cycle. Moreover, lithiated oxygen terminated MXenes surfaces are able to adsorb addnl. Li beyond a monolayer, providing a mechanism to substantially increase capacity, as obsd. mainly in delaminated MXenes and confirmed by DFT calcns. and XAS. The calcd. Li diffusion barriers are low, indicative of the measured high-rate performance. We predict the not yet synthesized Cr2C to possess high Li capacity due to the low activation energy of water formation at high temp., while the not yet synthesized Sc2C is predicted to potentially display low Li capacity due to higher reaction barriers for OH removal.
- 28Liu, L.; Lin, Z.; Chane-Ching, J. Y.; Shao, H.; Taberna, P. L.; Simon, P. 3D RGO Aerogel with Superior Electrochemical Performance for K – Ion Battery. Energy Storage Mater. 2019, 19, 306– 313, DOI: 10.1016/j.ensm.2019.03.013Google ScholarThere is no corresponding record for this reference.
- 29Guan, Y.; Zhang, M.; Qin, J.; Ma, X.; Li, C.; Tang, J. Hydrophilicity-Dependent Distinct Frictional Behaviors of Different Modified MXene Nanosheets. J. Phys. Chem. C 2020, 124 (25), 13664– 13671, DOI: 10.1021/acs.jpcc.0c01551Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVCrsLrI&md5=861dbac90d7c896caec69480dae5f36cHydrophilicity-Dependent Distinct Frictional Behaviors of Different Modified MXene NanosheetsGuan, Yanxue; Zhang, Miaomiao; Qin, Juan; Ma, Xingxing; Li, Chen; Tang, JilinJournal of Physical Chemistry C (2020), 124 (25), 13664-13671CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)MXene nanosheets are promising to be ultrathin solid lubricant or interface solving the friction and wear problems of miniaturized equipment. Here, the frictional behaviors and adhesive properties of the Ti3C2, F-Ti3C2, and TMA-Ti3C2 nanosheets were explored by at. force microscope for the first time. The nanofrictional behavior of TMA-Ti3C2 was significantly different from that of Ti3C2 and F-Ti3C2. The friction of TMA-Ti3C2 increased slightly and then decreased as the load decreased, leading to the appearance of a neg. friction factor; the frictions of Ti3C2 and F-Ti3C2 decreased with decreasing load, resulting in pos. friction factors. Meanwhile, because the surface of TMA-Ti3C2 was more hydrophilic than that of Ti3C2 and F-Ti3C2, the friction and adhesion of TMA-Ti3C2 were greater than those of Ti3C2 and F-Ti3C2. It indicated that the surface properties played an important role in the adhesion and friction. Hence, adjusting the surface properties of MXene nanosheets will provide a new direction for designing solid lubricants and nanointerfaces in micro- and nanoelectromech. systems.
- 30Liu, J.; Liu, Z.; Zhang, H. B.; Chen, W.; Zhao, Z.; Wang, Q. W.; Yu, Z. Z. Ultrastrong and Highly Conductive MXene-Based Films for High-Performance Electromagnetic Interference Shielding. Adv. Electron. Mater. 2020, 6 (1), 1– 8, DOI: 10.1002/aelm.201901094Google ScholarThere is no corresponding record for this reference.
- 31Wang, P.; Lu, X.; Boyjoo, Y.; Wei, X.; Zhang, Y.; Guo, D.; Sun, S.; Liu, J. Pillar-Free TiO2/Ti3C2 Composite with Expanded Interlayer Spacing for High-Capacity Sodium Ion Batteries. J. Power Sources 2020, 451, 227756, DOI: 10.1016/j.jpowsour.2020.227756Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtlajurs%253D&md5=7ecde58494a71e12d91aa162dca3dcb4Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing for high-capacity sodium ion batteriesWang, Peiyuan; Lu, Xiaoxuan; Boyjoo, Yash; Wei, Xiaorong; Zhang, Yonghui; Guo, Dongjie; Sun, Shumin; Liu, JianJournal of Power Sources (2020), 451 (), 227756CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)The lamellar transition metal oxides, sulfides and carbides with expanded interlayer spacing have attracted wide attention due to their enlargeable interlayer diffusion channels and larger contact areas. However, the existence of pillars between the interlayer would occupy the inter layer voids, which would hinder the accommodation of more Li ion, Na ion and so on. Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing was prepd. by sintering the pre-intercalated pristine Ti3C2 with TMAOH under N2 atmosphere. The obtained TiO2/Ti3C2 composite showed remarkable capacity (237.8 mA-h g-1 at 100 mA g-1) and long-term stability (153 mA-h g-1after 100 cycles at c.d. of 600 mA g-1) as anode material for Na ion batteries. These remarkable electrochem. properties of pillar-free TiO2/Ti3C2 were ascribed to its effective expanded interlayer distance fixed by TiO2 nanoparticles attached on the edge plane of Ti3C2, pseudocapacitance contribution of TiO2 nanoparticles, and the synergistic effect between TiO2 and Ti3C2. This work offered a general strategy for fabricating pillar-free MXene-based composites with enlarged interlayer spacing.
- 32Arole, K.; Blivin, J. W.; Saha, S.; Zhao, X.; Holta, D. E.; Sarmah, A.; Cao, H.; Radovic, M.; Lutkenhaus, J. L.; Green, M. J. Water-Dispersible Ti 3C 2T z MXene Nanosheets by Acid-Free, Molten Salt Etching. Cell Press 2021, 1 (2), 35Google ScholarThere is no corresponding record for this reference.
Cited By
Click to copy section linkSection link copied!
This article is cited by 188 publications.
- Kunal Roy, Navya Rani M, Manikanta Palya Narayanaswamy, Tathagata Sardar, Vidyashankar S, Dinesh Rangappa. Rapid and Direct Conversion of the Ti3AlC2 MAX Phase to Ti3C2Tx MXene Nanosheets by a Supercritical Water-Assisted Etching Process. ACS Applied Nano Materials 2024, 7
(23)
, 27628-27639. https://doi.org/10.1021/acsanm.4c05612
- Haoming Ding, Youbing Li, Mian Li, Zhifang Chai, Qing Huang. Layered Transition Metal Carbides/Nitrides: From Chemical Etching to Chemical Editing. Accounts of Materials Research 2024, Article ASAP.
- Qing Feng, Mingyuan Dou, Jing Yang, Shuai Zou, Zhenpeng Li, Lixia Wei, Fuchuan Huang. Heterostructures Comprised of MXene Nanosheets for Tribology: A Review. ACS Applied Nano Materials 2024, 7
(19)
, 22379-22416. https://doi.org/10.1021/acsanm.4c04210
- Yixuan Yang, Shenglin Yang, Xiaohu Xia, Shigang Hui, Ben Wang, Bingsuo Zou, Yabin Zhang, Jianping Sun, John H. Xin. MXenes for Wearable Physical Sensors toward Smart Healthcare. ACS Nano 2024, 18
(36)
, 24705-24740. https://doi.org/10.1021/acsnano.4c08258
- Zimo Pang, Zhichao Chen, Jianyu Li, Dongdong Liu, Guangyue Zhang, Canshang Liu, Chengkai Du, Weiwei Zhou. Advances in Inorganic Foam Materials Fabricated Via Blowing Strategy: A Comprehensive Review. ACS Nano 2024, 18
(33)
, 21747-21778. https://doi.org/10.1021/acsnano.4c05321
- Mumtahina Mim, Khairul Habib, Sazratul Nayeem Farabi, Syed Awais Ali, Md Abu Zaed, Mohammad Younas, Saidur Rahman. MXene: A Roadmap to Sustainable Energy Management, Synthesis Routes, Stabilization, and Economic Assessment. ACS Omega 2024, 9
(30)
, 32350-32393. https://doi.org/10.1021/acsomega.4c04849
- Yueang Jin, Xueqian Zhang, Yongchun Zhu, Jiajia Ye, Yitai Qian, Zhiguo Hou. Reversible Deposition/Dissolution of Double Hydroxides to Modulate Electrolyte pH Enabling High-Performance Aqueous Zinc-Ion Batteries. ACS Applied Materials & Interfaces 2024, 16
(22)
, 28391-28401. https://doi.org/10.1021/acsami.4c01861
- Carina Büchner, Niels Kubitza, Ali M. Malik, John Jamboretz, Aysha A. Riaz, Yujiang Zhu, Christoph Schlueter, Martha R. McCartney, David J. Smith, Anna Regoutz, Jochen Rohrer, Christina S. Birkel. Chemical Conversions within the Mo–Ga–C System: Layered Solids with Variable Ga Content. Inorganic Chemistry 2024, 63
(17)
, 7725-7734. https://doi.org/10.1021/acs.inorgchem.4c00107
- Shaobo Tu, Longguo Qiu, Chen Liu, Fanshuai Zeng, You-You Yuan, Mohamed Nejib Hedhili, Valentina Musteata, Yinchang Ma, Kun Liang, Naisheng Jiang, Husam N. Alshareef, Xixiang Zhang. Suppressing Dielectric Loss in MXene/Polymer Nanocomposites through Interfacial Interactions. ACS Nano 2024, 18
(14)
, 10196-10205. https://doi.org/10.1021/acsnano.4c00475
- Teng Zhang, Kateryna Shevchuk, Ruocun John Wang, Hyunho Kim, Jamal Hourani, Yury Gogotsi. Delamination of Chlorine-Terminated MXene Produced Using Molten Salt Etching. Chemistry of Materials 2024, 36
(4)
, 1998-2006. https://doi.org/10.1021/acs.chemmater.3c02872
- Eduardo Ruiz-Hitzky, Cristina Ruiz-Garcia, Xiaoying Wang. MXenes and Clay Minerals in the Framework of the 2D Organic–Inorganic Hybrid Nanomaterials. Chemistry of Materials 2023, 35
(24)
, 10295-10315. https://doi.org/10.1021/acs.chemmater.3c01759
- Jie Zhou, Martin Dahlqvist, Jonas Björk, Johanna Rosen. Atomic Scale Design of MXenes and Their Parent Materials─From Theoretical and Experimental Perspectives. Chemical Reviews 2023, 123
(23)
, 13291-13322. https://doi.org/10.1021/acs.chemrev.3c00241
- Varun Natu, Michel W. Barsoum. MXene Surface Terminations: A Perspective. The Journal of Physical Chemistry C 2023, 127
(41)
, 20197-20206. https://doi.org/10.1021/acs.jpcc.3c04324
- Teng Zhang, Christopher E. Shuck, Kateryna Shevchuk, Mark Anayee, Yury Gogotsi. Synthesis of Three Families of Titanium Carbonitride MXenes. Journal of the American Chemical Society 2023, 145
(41)
, 22374-22383. https://doi.org/10.1021/jacs.3c04712
- Jingxuan Cui, Jiao Wu, Le Mi, Aihu Feng, Yang Yu, Yun Yu. Effects of the Etching Process on Infrared Emissivity Properties of Ti3C2Tx MXene: Implications for Infrared Stealth. ACS Applied Nano Materials 2023, 6
(19)
, 18354-18363. https://doi.org/10.1021/acsanm.3c03664
- Kateryna Shevchuk, Asia Sarycheva, Christopher E. Shuck, Yury Gogotsi. Raman Spectroscopy Characterization of 2D Carbide and Carbonitride MXenes. Chemistry of Materials 2023, 35
(19)
, 8239-8247. https://doi.org/10.1021/acs.chemmater.3c01742
- Prakash Chandra . Emerging Trends in Advanced Synthesis and Properties: Mxenes as Super Materials. , 71-100. https://doi.org/10.1021/bk-2023-1442.ch004
- Bartholomew Richard, Susmi Anna Thomas, Amarendar Reddy M, Mohan Reddy Pallavolu, Jayesh Cherusseri. Minireview on Fluid Manipulation Techniques for the Synthesis and Energy Applications of Two-Dimensional MXenes: Advances, Challenges, and Perspectives. Energy & Fuels 2023, 37
(10)
, 6999-7013. https://doi.org/10.1021/acs.energyfuels.3c00589
- Wei Qi, Yuqi He, Mengjie Li, Wentao Chen, Jun Yang, Long Zhao. Fabrication Strategy of MXenes through Ionic-Liquid-Based Microemulsions toward Supercapacitor Electrodes. Langmuir 2022, 38
(45)
, 13995-14003. https://doi.org/10.1021/acs.langmuir.2c02373
- Guillaume Jeanmairet, Benjamin Rotenberg, Mathieu Salanne. Microscopic Simulations of Electrochemical Double-Layer Capacitors. Chemical Reviews 2022, 122
(12)
, 10860-10898. https://doi.org/10.1021/acs.chemrev.1c00925
- Varun Natu, Rahul Pai, Olivia Wilson, Edward Gadasu, Hussein Badr, Avishek Karmakar, Andrew J. D. Magenau, Vibha Kalra, Michel W. Barsoum. Effect of Base/Nucleophile Treatment on Interlayer Ion Intercalation, Surface Terminations, and Osmotic Swelling of Ti3C2Tz MXene Multilayers. Chemistry of Materials 2022, 34
(2)
, 678-693. https://doi.org/10.1021/acs.chemmater.1c03390
- Wen Siong Poh, Wen Jie Yiang, Do Yee Hoo, Sheng Qiang Zheng, Poi Sim Khiew, Chuan Yi Foo. MXene-based nanomaterials as anode materials. 2025, 473-525. https://doi.org/10.1016/B978-0-443-13338-1.00012-5
- Nadeem Hussain Solangi, Lakshmi Prasanna Lingamdinne, Rama Rao Karri, Nabisab Mujawar Mubarak, Shaukat Ali Mazari, Janardhan Reddy Koduru. Emerging 2D MXene quantum dots for catalytic conversion of CO2. Carbon 2025, 232 , 119758. https://doi.org/10.1016/j.carbon.2024.119758
- Jiaxin Quan, Xupu Jiang, Ting Ding, Wujun Ma, Min Li, Chuntao Lan, Hengxue Xiang, Wanfei Li, Meifang Zhu, Yuegang Zhang. Recent progress in MXene fiber: Materials, fabrication techniques, and potential applications. Chemical Engineering Journal 2025, 503 , 158320. https://doi.org/10.1016/j.cej.2024.158320
- Xiangrui Chen, Chengdeng Wang, Haofeng Shi, Jinpeng Li, Jiashuai Wang, Zhi Wang, Zhaokun Wang, Liyuan Bai, Yan Gao, Guanyong Wang, Yousong Gu, Xiaoqin Yan. Enhanced sodium storage in MXene transition metal chalcogenides anode through dual molten salt etching. Electrochimica Acta 2025, 509 , 145334. https://doi.org/10.1016/j.electacta.2024.145334
- Jeconiah J.M. Siregar, Early Zahwa Alharissa, Grandprix T.M. Kadja. Latest developments in the design and fabrication of two-dimensional carbides and nitrides (MXenes). Surfaces and Interfaces 2025, 56 , 105686. https://doi.org/10.1016/j.surfin.2024.105686
- K. Karuppasamy, Ganesh Kumar Veerasubramani, Vishwanath Hiremath, Dhanasekaran Vikraman, P. Santhoshkumar, Georgios N. Karanikolos, Ali Abdulkareem Alhammadi, Hyun-Seok Kim, Akram Alfantazi. Unlocking recent progress in niobium and vanadium carbide-based MXenes for sodium-ion batteries. Journal of Materials Chemistry A 2025, 119 https://doi.org/10.1039/D4TA05669H
- Eric Campbell, Alex Brown, Huynh Tam Minh Nguyen, Kelin He, Munkhbayar Batmunkh, Yu Lin Zhong. Recent Advances in Selective Chemical Etching of Nanomaterials for High‐Performance Electrodes in Electrocatalysis and Energy Storage. Small 2024, 4 https://doi.org/10.1002/smll.202409552
- Yan Wang, Liang Huang. Recent Advances in Salt‐Assisted Synthesis of 2D Materials. Small 2024, 33 https://doi.org/10.1002/smll.202410028
- Xiaoling He, Chengqiang Cui, Ying Chen, Li Zhang, Xinxin Sheng, Delong Xie. MXene and Polymer Collision: Sparking the Future of High‐Performance Multifunctional Coatings. Advanced Functional Materials 2024, 34
(51)
https://doi.org/10.1002/adfm.202409675
- Zhijie Cui, Pengwei Zhao, Honghai Wang, Chunli Li, Wenchao Peng, Jiapeng Liu. Tandem Effect Promotes MXene‐Supported Dual‐Site Janus Nanoparticles for High‐Efficiency Nitrate Reduction to Ammonia and Energy Output through Zn‐Nitrate Battery. Advanced Functional Materials 2024, 34
(52)
https://doi.org/10.1002/adfm.202410941
- Sunil Kumar, Syed Muhammad Zain Mehdi, Yongho Seo. 1D MXenes: Synthesis, Properties, and Applications. Small 2024, 20
(49)
https://doi.org/10.1002/smll.202405576
- Basiru O. Yusuf, Mustapha Umar, Mansur Aliyu, Aliyu M. Alhassan, Mohammed Mosaad Awad, Omer A. Taialla, AbdulHakam Shafiu Abdullahi, Jamilu Nura Musa, Khalid R. Alhooshani, Saheed A. Ganiyu. Recent advances and future prospects of MXene-based photocatalysts in environmental remediations. Journal of Environmental Chemical Engineering 2024, 12
(6)
, 114812. https://doi.org/10.1016/j.jece.2024.114812
- KA Sree Raj, Minjun Hwang, Srinivasan Alagar, Seungheon Choi, Chandra Sekhar Rout, Sang Mun Jeong, Ho Seok Park. MXenes for hybrid metal-ion storage and desalination. Journal of Energy Chemistry 2024, 2 https://doi.org/10.1016/j.jechem.2024.12.013
- Ting Yan, L.C. Xu, W.G. Pan, L.W. Wang. MXene - A frontier exploiter in carbon dioxide conversion: Synthesis and adsorption. Nano Today 2024, 59 , 102546. https://doi.org/10.1016/j.nantod.2024.102546
- Zhiwei Gao, Wei Lai. Structurally‐Modulated Substrate of MXene for Surface‐Enhanced Raman Scattering Sensing. ChemPhysChem 2024, 1 https://doi.org/10.1002/cphc.202400604
- Swedha Madhu, Jayden MacKenzie, Kuljeet Singh Grewal, Aitazaz A. Farooque, Ghada I. Koleilat, Gurpreet Singh Selopal. Titanium Carbide (Ti
3
C
2
T
x
) MXene for Sequestration of Aquatic Pollutants. ChemSusChem 2024, 17
(21)
https://doi.org/10.1002/cssc.202400421
- Xiao-Wen Dai, Zheng-Ran Wang, Xiao-Long Wang, Jing-Yun Chun, Chuan-Liang Wei, Li-Wen Tan, Jin-Kui Feng. MXene-based sodium–sulfur batteries: synthesis, applications and perspectives. Rare Metals 2024, 36 https://doi.org/10.1007/s12598-024-03022-y
- Alsha Subash, Sanchari Sen, Minoo Naebe, Balasubramanian Kandasubramanian, Manisha Kulthe, Akansha Kore. MXene
—Reclaimed Cellulose Acetate Composites for Methylene Blue Removal Through Synergistic Adsorption and Photocatalysis. Polymers for Advanced Technologies 2024, 35
(11)
https://doi.org/10.1002/pat.6622
- Xianglong Kong, Xiaohang Zong, Zijin Lei, Zicong Wang, Ying Zhao, Xudong Zhao, Junming Zhang, Zhiliang Liu, Yueming Ren, Linzhi Wu, Milin Zhang, Fei He, Piaoping Yang. A Universal In‐Situ Interfacial Growth Strategy for Various MXene‐Based van der Waals Heterostructures with Uniform Heterointerfaces: The Efficient Conversion from 3D Composite to 2D Heterostructures. Small 2024, 20
(45)
https://doi.org/10.1002/smll.202405174
- Arumugam Sangili, Binesh Unnikrishnan, Shun Ruei Hu, Han-Wei Chu, Hung-Lung Chou, Ren-Siang Wu, Chih-Ching Huang, Huan-Tsung Chang. Ammonia-assisted heterocyclic amine exerts soft delamination and interlayer engineering of Ti3C2Tx MXene for fabricating stable supercapacitors. Energy Storage Materials 2024, 73 , 103809. https://doi.org/10.1016/j.ensm.2024.103809
- Sahil Jangra, Bhushan Kumar, Jaishree Sharma, Shilpi Sengupta, Subhankar Das, R.K. Brajpuriya, Anil Ohlan, Yogendra Kumar Mishra, M.S. Goyat. A review on overcoming challenges and pioneering advances: MXene-based materials for energy storage applications. Journal of Energy Storage 2024, 101 , 113810. https://doi.org/10.1016/j.est.2024.113810
- Hanh An Nguyen, Nguyen Tran Truc Phuong, Thi Ngoc Diep Trinh, Nhu Hoa Thi Tran, Kieu The Loan Trinh. Synthesis and applications of MXene-based materials in biosensors for screening infectious pathogens. Sensors and Actuators A: Physical 2024, 378 , 115784. https://doi.org/10.1016/j.sna.2024.115784
- Yu Song, Zeshan Sun, Peng Kong, He Gui, Yuchao Li, Yanxin Wang, Jianguo Tang, Linjun Huang. Recent advances in MXene based intelligent sensing. Chemical Engineering Journal 2024, 500 , 157305. https://doi.org/10.1016/j.cej.2024.157305
- Narendra Bandaru, Ch.Venkata Reddy, Kalyani Vallabhudasu, Mule Vijayalakshmi, Kakarla Raghava Reddy, Bai Cheolho, Jaesool Shim, Tejraj M. Aminabhavi. Exploring the potential of MXene nanohybrids as high-performance anode materials for lithium-ion batteries. Chemical Engineering Journal 2024, 500 , 157317. https://doi.org/10.1016/j.cej.2024.157317
- Akhila Raman, Jitha S. Jayan, B. D. S. Deeraj, Manju Srivastava, Kuruvilla Joseph, Appukuttan Saritha. Delamination of
MXene
using biomolecule: An effective strategy toward the utilization of delaminated
MXene
as fillers in polymer composites. Polymer Composites 2024, 23 https://doi.org/10.1002/pc.29163
- Zhiqiang Li, Kemeng Liao, Lihong Yin, Zongrun Li, Yingzhi Li, Hongzhi Wang, Ning Qin, Shuai Gu, Jingjing Chen, Weihua Wan, Zhouguang Lu. Synergistic dual-interface engineering with self-organizing Li-ion/electric fields for enhanced lithium metal anode stability. Journal of Materials Chemistry A 2024, 12
(39)
, 26636-26644. https://doi.org/10.1039/D4TA03128H
- Muhammad Nazim Lakhan, Abdul Hanan, Yuan Wang, Hiang Kwee Lee, Hamidreza Arandiyan. Integrated MXene and metal oxide electrocatalysts for the oxygen evolution reaction: synthesis, mechanisms, and advances. Chemical Science 2024, 15
(38)
, 15540-15564. https://doi.org/10.1039/D4SC04141K
- Amar M. Patil, Arti A. Jadhav, Nilesh R. Chodankar, Ajay T. Avatare, Jongwoo Hong, Suprimkumar D. Dhas, Umakant M. Patil, Seong Chan Jun. Recent progress of MXene synthesis, properties, microelectrode fabrication techniques for microsupercapacitors and microbatteries energy storage devices and integration: A comprehensive review. Coordination Chemistry Reviews 2024, 517 , 216020. https://doi.org/10.1016/j.ccr.2024.216020
- Kahila Baghchesaraee, Ehsan Ghasali, Saleem Raza, Andrii Babenko, Giti Paimard, Tariq Bashir, Hossein Maleki-Ghaleh, Li Jie, Yasin Orooji. Recent advancements in MXenes synthesis, properties, and cutting-edge applications: A comprehensive review. Journal of Environmental Chemical Engineering 2024, 12
(5)
, 113546. https://doi.org/10.1016/j.jece.2024.113546
- Kai Chio Chan, Xiang Guan, Teng Zhang, Kailing Lin, Yihe Huang, Lingshu Lei, Yiannis Georgantas, Yury Gogotsi, Mark A. Bissett, Ian A. Kinloch. The fabrication of Ti
3
C
2
and Ti
3
CN MXenes by electrochemical etching. Journal of Materials Chemistry A 2024, 12
(37)
, 25165-25175. https://doi.org/10.1039/D4TA03457K
- Xiaobo Li, Shan Wang, Minyan Zheng, Zhanying Ma, Yan Chen, Lingjuan Deng, Weixia Xu, Guang Fan, Sanaz Khademolqorani, Seyedeh Nooshin Banitaba, Ahmed I. Osman. Synergistic integration of MXene nanostructures into electrospun fibers for advanced biomedical engineering applications. Nanoscale Horizons 2024, 9
(10)
, 1703-1724. https://doi.org/10.1039/D4NH00209A
- Weiyan Jiang, Zihan Gao, Miao Shen, Rui Tang, Jing Zhou, Chuanqiang Wu, Linjuan Zhang, Jian-Qiang Wang. Synthesis of two-dimensional N-terminated molybdenum carbides using an alloying strategy in molten salt. Journal of Materials Chemistry A 2024, 12
(36)
, 24195-24202. https://doi.org/10.1039/D4TA03999H
- Mengni Jiang, Di Wang, Young‐Hwan Kim, Chunying Duan, Dmitri V. Talapin, Chenkun Zhou. Evolution of Surface Chemistry in Two‐Dimensional MXenes: From Mixed to Tunable Uniform Terminations. Angewandte Chemie 2024, 136
(37)
https://doi.org/10.1002/ange.202409480
- Mengni Jiang, Di Wang, Young‐Hwan Kim, Chunying Duan, Dmitri V. Talapin, Chenkun Zhou. Evolution of Surface Chemistry in Two‐Dimensional MXenes: From Mixed to Tunable Uniform Terminations. Angewandte Chemie International Edition 2024, 63
(37)
https://doi.org/10.1002/anie.202409480
- Faiza Bibi, Abdul Hanan, Irfan Ali Soomro, Arshid Numan, Mohammad Khalid. Double transition metal
MXenes
for enhanced electrochemical applications: Challenges and opportunities. EcoMat 2024, 6
(9)
https://doi.org/10.1002/eom2.12485
- Dong Liu, Jimei Liu, Chong Li, Yanwen Ji, Yuxuan Han, Zhiwei Xue, Quanyong Lv, Jintao Chen, Yongxiao Wang, Hui Li. Tailoring surface terminals on MXene enables high-efficiency electromagnetic absorption. Carbon 2024, 228 , 119392. https://doi.org/10.1016/j.carbon.2024.119392
- Pengfei Huang, Hangjun Ying, Shunlong Zhang, Wei-Qiang Han. Recent advances and perspectives of MXene sediment: Composition, morphology, properties and applications. Coordination Chemistry Reviews 2024, 515 , 215964. https://doi.org/10.1016/j.ccr.2024.215964
- Suresh Jayakumar, P. Chinnappan Santhosh, S. Ramakrishna, A.V. Radhamani. 2D (Ti3C2Tx) MXene: A comprehensive review of advancements in synthesis protocols, applications in supercapacitors, sustainability targets and future prospects. Journal of Energy Storage 2024, 97 , 112741. https://doi.org/10.1016/j.est.2024.112741
- Mohammed Askkar Deen, Harish Kumar Rajendran, Ragavan Chandrasekar, Debanjana Ghosh, Selvaraju Narayanasamy. The Rise of Ti3C2Tx MXene synthesis strategies over the decades: A review. FlatChem 2024, 47 , 100734. https://doi.org/10.1016/j.flatc.2024.100734
- Xin Sun, Jun Wang, Jing Yu, Yifu Jing, Jingyuan Liu, Manish Singh, Peter D. Lund, Muhammad Imran Asghar. Self-assembled formation of platinum single atoms and nanoclusters stabilized on MXene as an efficient catalyst for boosting electrocatalytic hydrogen evolution. International Journal of Hydrogen Energy 2024, 84 , 502-510. https://doi.org/10.1016/j.ijhydene.2024.08.263
- Zhongyue Zhang, Yuan Ji, Qiu Jiang, Chuan Xia. Molten-salt synthesized MXene for catalytic applications: A review. Chemical Physics Reviews 2024, 5
(3)
https://doi.org/10.1063/5.0215613
- Aruzhan Keneshbekova, Gaukhar Smagulova, Bayan Kaidar, Aigerim Imash, Akram Ilyanov, Ramazan Kazhdanbekov, Eleonora Yensep, Aidos Lesbayev. MXene/Carbon Nanocomposites for Water Treatment. Membranes 2024, 14
(9)
, 184. https://doi.org/10.3390/membranes14090184
- Siva Nemala Sankar, Guilherme Araujo, João Fernandes, Fatima Cerqueira, Pedro Alpuim, Ana R. Ribeiro, Filipa Lebre, Ernesto Alfaro‐Moreno, Ernesto Placidi, Sergio Marras, Andrea Capasso. Eco‐Friendly Production of 2D Ti
3
C
2
T
x
MXene and Cytotoxicity Mitigation Toward Biomedical Applications. Advanced Materials Interfaces 2024, 11
(24)
https://doi.org/10.1002/admi.202400203
- Yanhui Xue, Shaofei Chao, Man Xu, Qiong Wu, Qijian Zhang, Yan-Jun Liu, Fufa Wu, Liang Liu, Muhammad Sufyan Javed, Wei Zhang. Multi-layers hexagonal hole MXene trap constructed by carbon vacancy defect regulation strategy enables high energy density potassium-ions storage. Energy Storage Materials 2024, 71 , 103558. https://doi.org/10.1016/j.ensm.2024.103558
- Peng Liu, Yahao Zhao, Wen Liu, Furong Ye, Hui Lv, Zhuo Peng, Changcun Han, Xinguo Ma, Jiayi Tian, Difu Zhan, Qian Fu, Yizhong Huang. In situ oxidative growth to form compact TiO2–Ti3C2 heterojunctions for photocatalytic hydrogen evolution. International Journal of Hydrogen Energy 2024, 80 , 1243-1254. https://doi.org/10.1016/j.ijhydene.2024.07.255
- Muhammad Zubair, Ronak Shahin Radkiany, Muhammad Bilal, I. Ihsanullah. MXenes: Innovative solutions for the removal of radionuclides from water - A review. Materials Science in Semiconductor Processing 2024, 178 , 108450. https://doi.org/10.1016/j.mssp.2024.108450
- Maria Leonor Matias, Cláudia Pereira, Henrique Vazão Almeida, Santanu Jana, Shrabani Panigrahi, Ugur Deneb Menda, Daniela Nunes, Elvira Fortunato, Rodrigo Martins, Suman Nandy. 3D printed MXene architectures for a plethora of smart applications. Materials Today Advances 2024, 23 , 100512. https://doi.org/10.1016/j.mtadv.2024.100512
- ZhiYong ZENG, Feng CAO, Jian HUANG, FengHua ZHANG, Kun QIAN, WenBing LI. Progress in the preparation of polymer-based MXene-enhanced electromagnetic shielding composites by electrospinning. SCIENTIA SINICA Technologica 2024, 54
(8)
, 1496-1518. https://doi.org/10.1360/SST-2023-0393
- Dawid D. Kruger, Hermenegildo García, Ana Primo. Molten Salt Derived MXenes: Synthesis and Applications. Advanced Science 2024, 11 https://doi.org/10.1002/advs.202307106
- Yuchen Pang, Junxiao Li, Kangle Lv, Dingguo Tang, Qin Li. A review on surface modulation of MXenes and the impact on their work functions and stability. New Journal of Chemistry 2024, 48
(28)
, 12477-12495. https://doi.org/10.1039/D4NJ02315C
- Zifeng Lin, Liyuan Liu, Patrice Simon. MXene Capacitive Behaviors and Supercapacitor Devices. 2024, 485-513. https://doi.org/10.1002/9781119869528.ch19
- Varun Natu, Michel W. Barsoum. Guidelines on the Intercalation of Ions and Molecules in MXenes. 2024, 109-136. https://doi.org/10.1002/9781119869528.ch6
- Mayank Pandey, Kaili Gong, Deepthi Jayan K, Keqing Zhou. Synthesis approaches of MXene based polymeric nano system for electromagnetic shielding Application- A review. Critical Reviews in Solid State and Materials Sciences 2024, 49
(4)
, 754-805. https://doi.org/10.1080/10408436.2023.2263485
- Syed Sheraz Ali, Manmatha Mahato, Do Van Lam, Pradeep Sambyal, Geetha Valurouthu, Mousumi Garai, Anweshi Dewan, Van Hiep Nguyen, Mannan Khan, Ashhad Kamal Taseer, Chi Won Ahn, Il‐Kwon Oh. MXene‐Cobalt Hybrid Electrodes for Electroactive Artificial Muscle. Advanced Engineering Materials 2024, 26
(13)
https://doi.org/10.1002/adem.202400515
- Chao Gao, Guoqiang Zhao, Xiaochao Zuo, Huaming Yang. Molten salt induced strong interaction between Co3O4 and montmorillonite for the promoted peroxymonosulfate activation toward tetracycline degradation. Applied Clay Science 2024, 255 , 107414. https://doi.org/10.1016/j.clay.2024.107414
- Xiaojing Zhao, Yingxue Li, Liying Yang, Shougen Yin. Construction of three-dimensional porous bimetallic MXene/carbon nanotubes/poly(p-phenylenediamine) hybrid electrode for high-performance lithium batteries. Journal of Energy Storage 2024, 93 , 112324. https://doi.org/10.1016/j.est.2024.112324
- Jipeng Fan, Haitao Wang, Wei Sun, Huiqin Duan, Jizhou Jiang. Recent developments and perspectives of Ti-based transition metal carbides/nitrides for photocatalytic applications: A critical review. Materials Today 2024, 76 , 110-135. https://doi.org/10.1016/j.mattod.2024.05.003
- Baoji Miao, Tariq Bashir, Hanlu Zhang, Tariq Ali, Saleem Raza, Delong He, Yu Liu, Jinbo Bai. Impact of various 2D MXene surface terminating groups in energy conversion. Renewable and Sustainable Energy Reviews 2024, 199 , 114506. https://doi.org/10.1016/j.rser.2024.114506
- Andrew M Fitzgerald, Emily Sutherland, Tarek Ali El-Melegy, Mary Qin Hassig, Julia L Martin, Erika Colin-Ulloa, Ken Ngo, Ronald L Grimm, Joshua R Uzarski, Michel W Barsoum, N Aaron Deskins, Lyubov V Titova, Kateryna Kushnir Friedman. Photoexcited charge carrier dynamics and electronic properties of two-dimensional MXene, Nb
2
CT
x. 2D Materials 2024, 11
(3)
, 035028. https://doi.org/10.1088/2053-1583/ad518d
- Kevinilo P. Marquez, Kim Marie D. Sisican, Rochelle P. Ibabao, Roy Alvin J. Malenab, Mia Angela N. Judicpa, Luke Henderson, Jizhen Zhang, Ken Aldren S. Usman, Joselito M. Razal. Understanding the Chemical Degradation of Ti
3
C
2
T
x
MXene Dispersions: A Chronological Analysis. Small Science 2024, 3 https://doi.org/10.1002/smsc.202400150
- Zeshan Ali Sandhu, Kainat Imtiaz, Muhammad Asam Raza, Adnan Ashraf, Areej Tubassum, Sajawal Khan, Umme Farwa, Ali Haider Bhalli, Abdullah G. Al-Sehemi. Beyond graphene: exploring the potential of MXene anodes for enhanced lithium–sulfur battery performance. RSC Advances 2024, 14
(28)
, 20032-20047. https://doi.org/10.1039/D4RA02704C
- Sunil Kumar, Nitu Kumari, Tej Singh, Yongho Seo. Shielding 2D MXenes against oxidative degradation: recent advances, factors and preventive measures. Journal of Materials Chemistry C 2024, 12
(23)
, 8243-8281. https://doi.org/10.1039/D4TC00884G
- Berfin Gürbüz, Fatih Ciftci. Bio-electric-electronics and tissue engineering applications of MXenes wearable materials: A review. Chemical Engineering Journal 2024, 489 , 151230. https://doi.org/10.1016/j.cej.2024.151230
- Ishara Wijesinghe, Sajani Wimalachandra, Hiran Chathuranga, Ifra Marriam, Buddhika Sampath Kumara, Yashodha Kondarage, Hanisha Ponnuru, Amir Abdolazizi, Mike Tebyetekerwa, Ruixiang Bai, Zhenkun Lei, Tuquabo Tesfamichael, Cheng Yan. Recent advances in MXene/elastomer nanocomposites: Synthesis, properties and applications. European Polymer Journal 2024, 214 , 113180. https://doi.org/10.1016/j.eurpolymj.2024.113180
- Kun Fang, Pei Li, Bing Zhang, Si Liu, Xiaoyang Zhao, Linxuan Kou, Wei Xu, Xiangyang Guo, Jianbin Li. Insights on updates in sodium alginate/MXenes composites as the designer matrix for various applications: A review. International Journal of Biological Macromolecules 2024, 269 , 132032. https://doi.org/10.1016/j.ijbiomac.2024.132032
- Ali Hamzehlouy, Masoud Soroush. MXene-based catalysts: A review. Materials Today Catalysis 2024, 5 , 100054. https://doi.org/10.1016/j.mtcata.2024.100054
- Irfan Ali Soomro, Muhammad Nazim Lakhan, Abdul Hanan, Hamad Almujibah, Altaf Hussain, Abdul Hameed Pato, Mukhtiar Ahmed, Imran Ali Chandio, Saeed Ahmed Memon, Muhammad Umer, Faiza Bibi, Ming Lei. 2D MXenes as electrode materials for metal-sulfur batteries: A review. Materials Today Physics 2024, 45 , 101453. https://doi.org/10.1016/j.mtphys.2024.101453
- Faqiang Wang, Yiming Liu, Jianyong Yu, Zhaoling Li, Bin Ding. Recent progress on general wearable electrical heating textiles enabled by functional fibers. Nano Energy 2024, 124 , 109497. https://doi.org/10.1016/j.nanoen.2024.109497
- Huaixuan Cao, Natalie N. Neal, Savannah Pas, Miladin Radovic, Jodie L. Lutkenhaus, Micah J. Green, Emily B. Pentzer. Architecting MXenes in polymer composites. Progress in Polymer Science 2024, 153 , 101830. https://doi.org/10.1016/j.progpolymsci.2024.101830
- Marley Downes, Christopher E. Shuck, Bernard McBride, Jeffrey Busa, Yury Gogotsi. Comprehensive synthesis of Ti3C2Tx from MAX phase to MXene. Nature Protocols 2024, 19
(6)
, 1807-1834. https://doi.org/10.1038/s41596-024-00969-1
- Yi-Zhao Chen, Ting-Ting Mao, Song-Yi Liao, Selina X. Yao, Yong-Gang Min. Layered Mo
x
B
y
(MBenes) derived by a molten-salt method and their application in advanced LIB anodes. Journal of Materials Chemistry A 2024, 12
(20)
, 12163-12172. https://doi.org/10.1039/D4TA00913D
- Israa Habeeb Naser, Youssef Ali Naeem, Eyhab Ali, Amina Yarab Hamed, Nafaa Farhan Muften, Fadhil Turky Maan, Israa Hussein Mohammed, Noor Alhuda Mohammad Ali Khalil, Irfan Ahmad, Mohammed Abed Jawad, Ahmed Elawady. Revolutionizing Infection Control: Harnessing MXene‐Based Nanostructures for Versatile Antimicrobial Strategies and Healthcare Advancements. Chemistry & Biodiversity 2024, 21
(5)
https://doi.org/10.1002/cbdv.202400366
- Jizhou Jiang, Fangyi Li, Lei Ding, Chengxun Zhang, Arramel, Xin Li. MXenes/CNTs-based hybrids: Fabrications, mechanisms, and modification strategies for energy and environmental applications. Nano Research 2024, 17
(5)
, 3429-3454. https://doi.org/10.1007/s12274-023-6302-x
- Yanhui Xue, Shaofei Chao, Man Xu, Qiong Wu, Jiayao Yu, Fufa Wu, Liang Liu, Muhammad Sufyan Javed, Wei Zhang. WITHDRAWN: Multi-layers hexagonal hole MXene trap constructed by carbon vacancy defect regulation strategy enables high energy density potassium-ions storage. Energy Storage Materials 2024, 5 , 103485. https://doi.org/10.1016/j.ensm.2024.103485
- Mojtaba Rostami, Alireza Badiei, Ghodsi Mohammadi Ziarani. A review of recent progress in the synthesis of 2D Ti3C2T MXenes and their multifunctional applications. Inorganic Chemistry Communications 2024, 163 , 112362. https://doi.org/10.1016/j.inoche.2024.112362
- Abdul Hanan, Hafiz Taimoor Ahmed Awan, Faiza Bibi, Raja Rafidah Raja Sulaiman, Wai Yin Wong, Rashmi Walvekar, Seema Singh, Mohammad Khalid. MXenes and heterostructures-based electrocatalysts for hydrogen evolution reaction: Recent developments and future outlook. Journal of Energy Chemistry 2024, 92 , 176-206. https://doi.org/10.1016/j.jechem.2024.01.038
- Kefayat Ullah, Noor Alam, Salah Uddin, Won-Chun Oh. Advanced concept and perspectives toward MXenes based energy storage device: Comprehensive review. Materialia 2024, 34 , 102089. https://doi.org/10.1016/j.mtla.2024.102089
- Yi-Lin Liu, Dongyang Li, Ping Cao, Xiangbiao Yin, Qingyi Zeng, Haiqing Zhou. Advances in MXene-based composite materials for efficient removal of radioactive nuclides and heavy metal ions. Materials Today Physics 2024, 44 , 101444. https://doi.org/10.1016/j.mtphys.2024.101444
- Md. Tanvir Hossaın, Md. Reazuddin Repon, Md. Abdus Shahid, Ayub Ali, Tarikul Islam. Progress, Prospects and Challenges of MXene Integrated Optoelectronics Devices. ChemElectroChem 2024, 11
(8)
https://doi.org/10.1002/celc.202400008
Learn about these metrics
了解这些指标
了解这些指标
Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.
Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.
Recommended Articles 推荐文章
Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide (Ti3C2Tx MXene)
二维碳化钛 （Ti 3 C 2 T x MXene） 的合成和加工指南September 6， 2017材料化学Delamination of Chlorine-Terminated MXene Produced Using Molten Salt Etching
使用熔盐蚀刻生产的氯封端 MXene 的分层2024 年 2 月 6 日材料化学Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes
The Rise of MXenes
Modified MAX Phase Synthesis for Environmentally Stable and Highly Conductive Ti3C2 MXene
Sponsored Content
Newly redesigned for on-demand delivery, this course empowers you with the essential knowledge to be able to effectively communicate and think like a chemist.
Abstract 抽象
Figure 1 图 1
Figure 1. Schematic and realistic views of the molten salt synthesis method and exfoliation process. (a) Schematic representation of the synthesis and exfoliation of MXene prepared via a Lewis acidic etching route. Pristine MS-Ti3C2Tx before (left) and after (right) TBAOH treatment after (b) centrifugation at 3500 rpm for 30 min and (c) collection by filtration. (d) Tyndall effect for nanoflakes dispersed in water after TBAOH treatment.
图 1.熔盐合成方法和剥离过程的示意图和实景图。（a） 通过 Lewis 酸性蚀刻路线制备的 MXene 合成和剥离的示意图。（b） 以 3500 rpm 离心 30 分钟和 （c） 过滤收集后，TBAOH 处理前（左）和后（右）的原始 MS-Ti 3 C 2 T x 。（d） TBAOH 处理后分散在水中的纳米薄片的 Tyndall 效应。Figure 2
Figure 2. Material characterization of e-MS-Ti3C2Tx. (a) XRD patterns of pristine Ti3AlC2 before (black line) and after (red line) reaction with CuCl2, multilayered MS-Ti3C2Tx (blue line), and e-MS-Ti3C2Tx (green line) TBAOH treatment. SEM graph of (b) MS-Ti3C2Tx MXene and (c) e-MS-Ti3C2Tx (collected by filtration). (d) TEM graph of e-MS-Ti3C2Tx. (e) Selected area electron diffraction (SAED) pattern and (f) HRTEM image of e-MS-Ti3C2Tx. Zeta potentials of (g) e-MS-Ti3C2Tx and (h) multilayered MS-Ti3C2Tx. (i) Mean size of multilayered MS-Ti3C2Tx (gray line) and e-MS-Ti3C2Tx (red line) in DI water.
Figure 3
Figure 3. Electrochemical characterization in 1 M LiPF6 in ethylene carbonate/dimethyl carbonate electrolyte of e-MS-Ti3C2Tx with a mass loading of around 1.1 mg cm–2. (a) First three CV cycles recorded at 1 mV s–1. (b) CVs recorded at various potential scan rates from 1 to 200 mV s–1. (c) Galvanostatic charge–discharge (GCD) curves recorded at various current density from 0.2 to 16 A g–1. (d) Discharge time and capacity values of a multilayer before (black line) and after (red line) TBAOH treatment from 0.2 A g–1 (1C) to 16 A g–1 (167.5C).
Figure 4
Figure 4. Evolution of MS-Ti3C2Tx in TBAOH and TMAOH. (a) Water contact angle of MS-Ti3C2Tx treated by TBAOH for 0, 12, 24, and 72 h, respectively. (b) SEM image of MS-Ti3C2Tx MXene after TMAOH treatment for 72 h, followed by an 18 h bath sonification and selection at 7000 rpm. (c) Photo showing the flexibility of the filtrated TMAOH-treated MS-MXene after selection.
References
This article references 32 other publications.
- 1Lukatskaya, M. R.; Mashtalir, O.; Ren, C. E.; Dall’Agnese, Y.; Rozier, P.; Taberna, P. L.; Naguib, M.; Simon, P.; Barsoum, M. W.; Gogotsi, Y. Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide. Science (Washington, DC, U. S.) 2013, 341 (6153), 1502– 1505, DOI: 10.1126/science.12414881https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFSmsLjO&md5=c700d741ed4085a1a8cb2cd6f3d30facCation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium CarbideLukatskaya, Maria R.; Mashtalir, Olha; Ren, Chang E.; Dall'Agnese, Yohan; Rozier, Patrick; Taberna, Pierre Louis; Naguib, Michael; Simon, Patrice; Barsoum, Michel W.; Gogotsi, YuryScience (Washington, DC, United States) (2013), 341 (6153), 1502-1505CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)The intercalation of ions into layered compds. has long been exploited in energy storage devices such as batteries and electrochem. capacitors. However, few host materials are known for ions much larger than lithium. We demonstrate the spontaneous intercalation of cations from aq. salt solns. between two-dimensional (2D) Ti3C2 MXene layers. MXenes combine 2D conductive carbide layers with a hydrophilic, primarily hydroxyl-terminated surface. A variety of cations, including Na+, K+, NH4+, Mg2+, and Al3+, can also be intercalated electrochem., offering capacitance in excess of 300 F per cubic centimeter (much higher than that of porous carbons). This study provides a basis for exploring a large family of 2D carbides and carbonitrides in electrochem. energy storage applications using single- and multivalent ions.
- 2Naguib, M.; Kurtoglu, M.; Presser, V.; Lu, J.; Niu, J.; Heon, M.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W. Two-Dimensional Nanocrystals Produced by Exfoliation of Ti 3AlC 2. Adv. Mater. 2011, 23 (37), 4248– 4253, DOI: 10.1002/adma.2011023062https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGisLnL&md5=2c476f3f7f645d96680e0f4c9c3513e0Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2Naguib, Michael; Kurtoglu, Murat; Presser, Volker; Lu, Jun; Niu, Junjie; Heon, Min; Hultman, Lars; Gogotsi, Yury; Barsoum, Michel W.Advanced Materials (Weinheim, Germany) (2011), 23 (37), 4248-4253CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Treatment of Ti3AlC2 powders for 2 h in HF results in the formation of exfoliated 2-dimensional (2D) Ti3C2 layers (nanosheets). The Ti3AlC2 structure is composed of individual Ti3C2 layers sepd. by Al atoms. Upon reaction with HF, Al atoms are removed from between the layers, resulting in the exfoliation of individual Ti3C2 layers from each other due to the loss of metallic bonding holding them together when the Al atoms are present. The exposed 2D Ti3C2 layers possess 2 exposed Ti atoms per unit formula that should be satisfied by suitable ligands. Since the expts. were conducted in an aq. environment rich in F ions, hydroxyl and F are the most probable ligands. Modeling of each case was conduced by attaching resp. ligands to the exposed Ti atoms followed by full geometry optimizations. The exposed Ti surfaces appear to be terminated by OH and/or F. The large elastic moduli predicted by ab initio simulation, and the possibility of varying their surface chem. render these nanosheets attractive as polymer composite fillers. The implications and importance of this work extend far beyond the results shown herein. There are over 60 currently known MAX phases; therefore, this work, in principle, opens the door for formation of a large no. of 2D Mn+1Xn structures, including the carbides and nitrides of Ti, V, Cr, Nb, Ta, Hf, and Zr. The latter could include 2D structures of combination of M-atoms, e.g., Ti0.5Zr0.5InC and/or different combinations of C and N, such as Ti2AlC0.5N0.5, if the selective chem. etching is extended to other MAX phases. We currently have solid evidence for the exfoliation of Ta4AlC3 into Ta4C3 flakes.
- 3Wang, X.; Mathis, T. S.; Li, K.; Lin, Z.; Vlcek, L.; Torita, T.; Osti, N. C.; Hatter, C.; Urbankowski, P.; Sarycheva, A.; Tyagi, M.; Mamontov, E.; Simon, P.; Gogotsi, Y. Influences from Solvents on Charge Storage in Titanium Carbide MXenes. Nat. Energy 2019, 4 (3), 241– 248, DOI: 10.1038/s41560-019-0339-93https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXmslKjurw%253D&md5=8ab785d740429399dee7cc50ec0e3e00Influences from solvents on charge storage in titanium carbide MXenesWang, Xuehang; Mathis, Tyler S.; Li, Ke; Lin, Zifeng; Vlcek, Lukas; Torita, Takeshi; Osti, Naresh C.; Hatter, Christine; Urbankowski, Patrick; Sarycheva, Asia; Tyagi, Madhusudan; Mamontov, Eugene; Simon, Patrice; Gogotsi, YuryNature Energy (2019), 4 (3), 241-248CODEN: NEANFD; ISSN:2058-7546. (Nature Research)Pseudocapacitive energy storage in supercapacitor electrodes differs significantly from the elec. double-layer mechanism of porous carbon materials, which requires a change from conventional thinking when choosing appropriate electrolytes. Here we show how simply changing the solvent of an electrolyte system can drastically influence the pseudocapacitive charge storage of the two-dimensional titanium carbide, Ti3C2 (a representative member of the MXene family). Measurements of the charge stored by Ti3C2 in lithium-contg. electrolytes with nitrile-, carbonate- and sulfoxide-based solvents show that the use of a carbonate solvent doubles the charge stored by Ti3C2 when compared with the other solvent systems. We find that the chem. nature of the electrolyte solvent has a profound effect on the arrangement of mols./ions in Ti3C2, which correlates directly to the total charge being stored. Having nearly completely desolvated lithium ions in Ti3C2 for the carbonate-based electrolyte leads to high volumetric capacitance at high charge-discharge rates, demonstrating the importance of considering all aspects of an electrochem. system during development.
- 4Beda, A.; Taberna, P. L.; Simon, P.; Matei Ghimbeu, C. Hard Carbons Derived from Green Phenolic Resins for Na-Ion Batteries. Carbon 2018, 139, 248– 257, DOI: 10.1016/j.carbon.2018.06.0364https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXht1GmsLrK&md5=11d925e13b5904589cee1f65b1e20779Hard carbons derived from green phenolic resins for Na-ion batteriesBeda, Adrian; Taberna, Pierre-Louis; Simon, Patrice; Matei Ghimbeu, CameliaCarbon (2018), 139 (), 248-257CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)Hard carbons have become recently one of the most promising classes of anode materials for Na ion batteries (NIBs) owing to their high specific capacity and good cycling stability. Among the precursors used to prep. hard C, phenolic resins are of great interest due to their high C yield, however, their toxicity must be overcome. The authors propose a green, simple and scalable procedure to obtain phenolic resins which by pyrolysis at high temp. (>1000°) result in eco-friendly hard carbons with low surface area, disordered structure and high C yield. The influence of several synthesis parameters (type of solvent, thermopolymn./annealing temp. and gas flow) was studied to det. the impact on both phenolic resin and hard C characteristics. The synthesis time (12 h-3 days) depends on the used solvent whereas the C yield (25-35%) on the crosslinking degree which could be controlled by adjusting both thermopolymn. temp. and atm. The structure of the hard carbons mainly changed with the carbonization temp. (1100-1700°) while the texture of the material was sensitive to most of the studied parameters. Stable reversible capacity up to 270 mA h g-1 and 100% coulombic efficiency (CE) after few cycles are obtained, demonstrating the potential for Na-ion applications.
- 5Lukatskaya, M. R.; Kota, S.; Lin, Z.; Zhao, M. Q.; Shpigel, N.; Levi, M. D.; Halim, J.; Taberna, P. L.; Barsoum, M. W.; Simon, P.; Gogotsi, Y. Ultra-High-Rate Pseudocapacitive Energy Storage in Two-Dimensional Transition Metal Carbides. Nat. Energy 2017, 6 (July), 1– 6, DOI: 10.1038/nenergy.2017.105There is no corresponding record for this reference.
- 6Simon, P. Two-Dimensional MXene with Controlled Interlayer Spacing for Electrochemical Energy Storage. ACS Nano 2017, 11 (3), 2393– 2396, DOI: 10.1021/acsnano.7b011086https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjvFygtrs%253D&md5=cf1962337f1b6cfbd37e344b0bead0a9Two-Dimensional MXene with Controlled Interlayer Spacing for Electrochemical Energy StorageSimon, PatriceACS Nano (2017), 11 (3), 2393-2396CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review is presented. In this issue of ACS Nano, Luo et al. report the prepn. of pillared two-dimensional (2D) Ti3C2 MXenes with controllable interlayer spacings between 1 and 2.708 nm. These materials were further intercalated by ion exchange with Sn(+IV) ions. The results show improved electrochem. performance due to improved ion accessibility into the 2D structure as well as the confinement effect, which limits vol. expansion during the Li-alloying reaction. Beyond this specific example, the demonstration that the interlayer spacings of MXenes can be fine-tuned by creating pillared structures based on the spontaneous intercalation of surfactants opens new perspectives in the field of electrochem. energy storage.
- 7Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y. 2D Metal Carbides and Nitrides (MXenes) for Energy Storage. Nat. Rev. Mater. 2017, 2 (2), DOI: 10.1038/natrevmats.2016.98 .There is no corresponding record for this reference.
- 8Hu, M.; Hu, T.; Li, Z.; Yang, Y.; Cheng, R.; Yang, J.; Cui, C.; Wang, X. Surface Functional Groups and Interlayer Water Determine the Electrochemical Capacitance of Ti3C2 T x MXene. ACS Nano 2018, 12 (4), 3578– 3586, DOI: 10.1021/acsnano.8b006768https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXmvVaru74%253D&md5=25f8b2c699e45197ee6b1f92c61a8b88Surface Functional Groups and Interlayer Water Determine the Electrochemical Capacitance of Ti3C2Tx MXeneHu, Minmin; Hu, Tao; Li, Zhaojin; Yang, Yi; Cheng, Renfei; Yang, Jinxing; Cui, Cong; Wang, XiaohuiACS Nano (2018), 12 (4), 3578-3586CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)MXenes, an emerging class of conductive two-dimensional materials, have been regarded as promising candidates in the field of electrochem. energy storage. The electrochem. performance of their representative Ti3C2Tx, where T represents the surface termination group of F, O, or OH, strongly relies on termination-mediated surface functionalization, but an in-depth understanding of the relationship between them remains unresolved. Here, we studied comprehensively the structural feature and electrochem. performance of two kinds of Ti3C2Tx MXenes obtained by etching the Ti3AlC2 precursor in aq. HF soln. at low concn. (6 mol/L) and high concn. of (15 mol/L). A significantly higher capacitance was recognized in a low-concn. HF-etched MXene (Ti3C2Tx-6M) electrode. In situ Raman spectroscopy and XPS demonstrate that Ti3C2Tx-6M has more components of the -O functional group. In combination with X-ray diffraction anal., low-field 1H NMR spectroscopy in terms of relaxation time unambiguously underlines that Ti3C2Tx-6M is capable of accommodating more high-mobility H2O mols. between the Ti3C2Tx interlayers, enabling more hydrogen ions to be more readily accessible to the active sites of Ti3C2Tx-6M. The two main key factors (i.e., high content of -O functional groups that are involved bonding/debonding-induced pseudocapacitance and more high-mobility water intercalated between the MXene interlayers) simultaneously account for the superior capacitance of the Ti3C2Tx-6M electrode. This study provides a guideline for the rational design and construction of high-capacitance MXene and MXene-based hybrid electrodes in aq. electrolytes.
- 9Moitzheim, S.; De Gendt, S.; Vereecken, P. M. Investigation of the Li-Ion Insertion Mechanism for Amorphous and Anatase TiO 2 Thin-Films. J. Electrochem. Soc. 2019, 166 (2), A1– A9, DOI: 10.1149/2.1091816jes9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXotVWlsrc%253D&md5=2e5297b1b3beead168d6a408a35afd03Investigation of the Li-ion insertion mechanism for amorphous and anatase TiO2 Thin-FilmsMoitzheim, S.; Gendt, S. De; Vereecken, P. M.Journal of the Electrochemical Society (2019), 166 (2), A1-A9CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)Titania is considered an interesting anode candidate for Li+-ion batteries, as it offers a high theor. capacity (1280 mAh cm-3 or 336 mAh g-1) and long term cycling stability. Unfortunately, the most commonly investigated anatase structure never reaches the theor. capacity at practical charging rates (i.e. above 1 C). In this work, we compare amorphous (am-TiO2) to anatase TiO2 thin-films, and investigate the exceptional performance of am-TiO2 as Li+-ion insertion electrode. An in-depth electrochem. characterization using cyclic voltammetry (CV), const. current lithiation and delithiation, and potentiostatic intermittent titrn. technique (PITT) is performed. From CV, the insertion and extn. kinetics of am-TiO2 is unrestricted by diffusion, contrary to anatase. Based on our combined electrochem. results, two different mechanisms are formulated for anatase and am- TiO2. Whereas anatase is filled from the "top-down", with a buildup of Li near the electrode/electrolyte interface, am-TiO2 shows a "bottom-up" filling mechanism. This discrepancy is ascribed to the difference in diffusion coeff. measured for am-TiO2 and anatase. This work highlights the differences of Li-ion insertion into amorphous TiO2 compared to anatase, and gives guidance on material development for high capacity and fast charging electrodes.
- 10Ghidiu, M.; Lukatskaya, M. R.; Zhao, M. Q.; Gogotsi, Y.; Barsoum, M. W. Conductive Two-Dimensional Titanium Carbide “Clay” with High Volumetric Capacitance. Nature 2014, 516 (7529), 78– 81, DOI: 10.1038/nature1397010https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVakt7zN&md5=ac29b037ec6f81f7b64dd05b878bf626Conductive two-dimensional titanium carbide 'clay' with high volumetric capacitanceGhidiu, Michael; Lukatskaya, Maria R.; Zhao, Meng-Qiang; Gogotsi, Yury; Barsoum, Michel W.Nature (London, United Kingdom) (2014), 516 (7529), 78-81CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)A conductive two-dimensional titanium carbide material (called "clay" because of its maleability and "shapeability") with a high volumetric capacitance is prepd. by etching titanium carbide (Ti3AlC2) with a soln. of LiF in concd. HCl. The resulting sediment (of general formula Ti3C2T, in which T denotes surface functionality) is a hydrophilic material that undergoes swelling when hydrated, and can be shaped like clay and dried into a highly conductive solid or rolled into films tens of micrometers thick. Additive-free films of this titanium carbide "clay" have volumetric capacitances of up to 900 F per cm3, and has excellent cyclability and rate performance. The prepn. method avoids the hazards of handling concd. hydrofluoric acid.
- 11Feng, A.; Yu, Y.; Jiang, F.; Wang, Y.; Mi, L.; Yu, Y.; Song, L. Fabrication and Thermal Stability of NH4HF2-Etched Ti3C2MXene. Ceram. Int. 2017, 43 (8), 6322– 6328, DOI: 10.1016/j.ceramint.2017.02.03911https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXis1Sjsrg%253D&md5=40e5c0733421dea5e3885cce94de37caFabrication and thermal stability of NH4HF2-etched Ti3C2 MXeneFeng, Aihu; Yu, Yun; Jiang, Feng; Wang, Yong; Mi, Le; Yu, Yang; Song, LixinCeramics International (2017), 43 (8), 6322-6328CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)MXene, a new family of 2D transition metal carbides and carbonitrides, has been proved to possess excellent elec. cond. and hydrophilicity. In this work, a single-step method to produce the larger interplanar spacing 2D MXene Ti3C2 by etching Ti3AlC2 with NH4HF2 was demonstrated, and the optimal reaction conditions between Ti3AlC2 and NH4HF2 were systematically researched. The morphol. and microstructure of samples were characterized by SEM (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). The thermal stability of Ti3C2 was investigated by the thermogravimetry (TG) and differential thermal analyzer (DTA). It was found that the lattice parameter c of obtained Ti3C2 was up to 24.9 Å, and the larger interplanar spacing Ti3C2 was more stable than the sample exfoliated by HF. The transition temp. in air from NH4HF2-etched Ti3C2 to anatase TiO2 thoroughly is more than 500°C, and the multilayered structure of Ti3C2 could be well retained even after 900°C heat treatment, while the value of HF-etched Ti3C2 is less than 350°C. This work is important for exploring a safe synthesis method and well understanding the thermal stability of 2D MXene materials.
- 12Li, M.; Lu, J.; Luo, K.; Li, Y.; Chang, K.; Chen, K.; Zhou, J.; Rosen, J.; Hultman, L.; Eklund, P.; Persson, P.; Du, S.; Chai, Z.; Huang, Z.; Huang, Q. Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes. J. Am. Chem. Soc. 2019, 141 (11), 4730– 4737, DOI: 10.1021/jacs.9b0057412https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXktVCiu7w%253D&md5=29c378a685955409963f771851acb591Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenesLi, Mian; Lu, Jun; Luo, Kan; Li, Youbing; Chang, Keke; Chen, Ke; Zhou, Jie; Rosen, Johanna; Hultman, Lars; Eklund, Per; Persson, Per O. A.; Du, Shiyu; Chai, Zhifang; Huang, Zhengren; Huang, QingJournal of the American Chemical Society (2019), 141 (11), 4730-4737CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesizing a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition-metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between the Zn element from molten ZnCl2 and the Al element in MAX phase precursors (Ti3AlC2, Ti2AlC, Ti2AlN, and V2AlC), novel MAX phases Ti3ZnC2, Ti2ZnC, Ti2ZnN, and V2ZnC were synthesized. When employing excess ZnCl2, Cl-terminated MXenes (such as Ti3C2Cl2 and Ti2CCl2) were derived by a subsequent exfoliation of Ti3ZnC2 and Ti2ZnC due to the strong Lewis acidity of molten ZnCl2. A-site element replacement in traditional MAX phases by late transition-metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temp. and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addn., this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to prepg. MXenes through an HF-free chem. approach.
- 13Li, Y.; Shao, H.; Lin, Z.; Lu, J.; Liu, L.; Duployer, B.; Persson, P. O. Å.; Eklund, P.; Hultman, L.; Li, M.; Chen, K.; Zha, X.; Du, S.; Rozier, P.; Chai, Z.; Raymundo-Piñero, E.; Taberna, P. L.; Simon, P.; Huang, Q. A General Lewis Acidic Etching Route for Preparing MXenes with Enhanced Electrochemical Performance in Non-Aqueous Electrolyte. Nat. Mater. 2020, 19 (8), 894– 899, DOI: 10.1038/s41563-020-0657-013https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXmvFylsrs%253D&md5=4b3f9d9b2c467a77dce144c51a394322A general Lewis acidic etching route for preparing MXenes with enhanced electrochemical performance in non-aqueous electrolyteLi, Youbing; Shao, Hui; Lin, Zifeng; Lu, Jun; Liu, Liyuan; Duployer, Benjamin; Persson, Per O. A.; Eklund, Per; Hultman, Lars; Li, Mian; Chen, Ke; Zha, Xian-Hu; Du, Shiyu; Rozier, Patrick; Chai, Zhifang; Raymundo-Pinero, Encarnacion; Taberna, Pierre-Louis; Simon, Patrice; Huang, QingNature Materials (2020), 19 (8), 894-899CODEN: NMAACR; ISSN:1476-1122. (Nature Research)Two-dimensional carbides and nitrides of transition metals, known as MXenes, are a fast-growing family of materials that have attracted attention as energy storage materials. MXenes are mainly prepd. from Al-contg. MAX phases (where A = Al) by Al dissoln. in F-contg. soln.; most other MAX phases have not been explored. Here a redox-controlled A-site etching of MAX phases in Lewis acidic melts is proposed and validated by the synthesis of various MXenes from unconventional MAX-phase precursors with A elements Si, Zn, and Ga. A neg. electrode of Ti3C2 MXene material obtained through this molten salt synthesis method delivers a Li+ storage capacity of ≤ 738 C g-1 (205 mAh g-1) with high charge-discharge rate and a pseudocapacitive-like electrochem. signature in 1 M LiPF6 carbonate-based electrolyte. MXenes prepd. via this molten salt synthesis route may prove suitable for use as high-rate neg.-electrode materials for electrochem. energy storage applications.
- 14Kamysbayev, V.; Filatov, A. S.; Hu, H.; Rui, X.; Lagunas, F.; Wang, D.; Klie, R. F.; Talapin, D. V. Covalent Surface Modifications and Superconductivity of Two-Dimensional Metal Carbide MXenes. Science (Washington, DC, U. S.) 2020, 369 (6506), 979– 983, DOI: 10.1126/science.aba831114https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1GrsbzL&md5=e353a4299a9744b88bd512bd5969a528Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenesKamysbayev, Vladislav; Filatov, Alexander S.; Hu, Huicheng; Rui, Xue; Lagunas, Francisco; Wang, Di; Klie, Robert F.; Talapin, Dmitri V.Science (Washington, DC, United States) (2020), 369 (6506), 979-983CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)Versatile chem. transformations of surface functional groups in two-dimensional transition-metal carbides (MXenes) open up a previously unexplored design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorg. salts. Successful synthesis of MXenes with oxygen, imido, sulfur, chlorine, selenium, bromine, and tellurium surface terminations, as well as bare MXenes (no surface termination), was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interat. distances in the MXene lattice, and Tin+1Cn (n = 1, 2) MXenes terminated with telluride (Te2-) ligands show a giant (>18%) in-plane lattice expansion compared with the unstrained titanium carbide lattice. The surface groups also control supercond. of niobium carbide MXenes.
- 15Li, M.; Li, X.; Qin, G.; Luo, K.; Lu, J.; Li, Y.; Liang, G.; Huang, Z.; Zhou, J.; Hultman, L.; Eklund, P.; Persson, P.O. Å.; Du, S.; Chai, Z.; Zhi, C.; Huang, Q. Halogenated Ti3C2MXenes with Electrochemically Active Terminals for High-Performance Zinc Ion Batteries. ACS Nano 2021, 15 (1), 1077– 1085, DOI: 10.1021/acsnano.0c0797215https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmtFykuw%253D%253D&md5=15e37cc12243369ff321efb594e0816fHalogenated Ti3C2 MXenes with Electrochemically Active Terminals for High-Performance Zinc Ion BatteriesLi, Mian; Li, Xinliang; Qin, Guifang; Luo, Kan; Lu, Jun; Li, Youbing; Liang, Guojin; Huang, Zhaodong; Zhou, Jie; Hultman, Lars; Eklund, Per; Persson, Per O. A.; Du, Shiyu; Chai, Zhifang; Zhi, Chunyi; Huang, QingACS Nano (2021), 15 (1), 1077-1085CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The class of two-dimensional metal carbides and nitrides known as MXenes offer a distinct manner of property tailoring for a wide range of applications. The ability to tune the surface chem. for expanding the property space of MXenes is thus an important topic, although exptl. exploration of surface terminals remains a challenge. Here, we synthesized Ti3C2 MXene with unitary, binary, and ternary halogen terminals, e.g., -Cl, -Br, -I, -BrI, and -ClBrI, to investigate the effect of surface chem. on the properties of MXenes. The electrochem. activity of Br and I elements results in the extraordinary electrochem. performance of the MXenes as cathodes for aq. zinc ion batteries. The -Br- and -I-contg. MXenes, e.g., Ti3C2Br2 and Ti3C2I2, exhibit distinct discharge platforms with considerable capacities of 97.6 and 135 mAh·g-1. Ti3C2(BrI) and Ti3C2(ClBrI) exhibit dual discharge platforms with capacities of 117.2 and 106.7 mAh·g-1. In contrast, the previously discovered MXenes Ti3C2Cl2 and Ti3C2(OF) exhibit no discharge platforms and only ~ 50% of capacities and energy densities of Ti3C2Br2. These results emphasize the effectiveness of the Lewis-acidic-melt etching route for tuning the surface chem. of MXenes and also show promise for expanding the MXene family toward various applications.
- 16Mashtalir, O.; Naguib, M.; Mochalin, V. N.; Dall’Agnese, Y.; Heon, M.; Barsoum, M. W.; Gogotsi, Y. Intercalation and Delamination of Layered Carbides and Carbonitrides. Nat. Commun. 2013, 4, 1– 7, DOI: 10.1038/ncomms2664There is no corresponding record for this reference.
- 17Alhabeb, M.; Maleski, K.; Anasori, B.; Lelyukh, P.; Clark, L.; Sin, S.; Gogotsi, Y. Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide (Ti3C2Tx MXene). Chem. Mater. 2017, 29 (18), 7633– 7644, DOI: 10.1021/acs.chemmater.7b0284717https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtlyhsLjN&md5=768044a456d251660fa0120ea6cf8557Guidelines for Synthesis and Processing of Two-Dimensional Titanium Carbide (Ti3C2Tx MXene)Alhabeb, Mohamed; Maleski, Kathleen; Anasori, Babak; Lelyukh, Pavel; Clark, Leah; Sin, Saleesha; Gogotsi, YuryChemistry of Materials (2017), 29 (18), 7633-7644CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXenes) were discovered in 2011. Since the original discovery, >20 different compns. have been synthesized by the selective etching of MAX phase and other precursors and many more theor. predicted. They offer a variety of different properties, making the family promising candidates in a wide range of applications, such as energy storage, electromagnetic interference shielding, water purifn., electrocatalysis, and medicine. These soln.-processable materials have the potential to be highly scalable, deposited by spin, spray, or dip coating, painted or printed, or fabricated in a variety of ways. Due to this promise, the amt. of research on MXenes has been increasing, and methods of synthesis and processing are expanding quickly. The fast evolution of the material can also be noticed in the wide range of synthesis and processing protocols that det. the yield of delamination, as well as the quality of the 2D flakes produced. Here we describe the exptl. methods and best practices we use to synthesize the most studied MXene, titanium carbide (Ti3C2Tx), using different etchants and delamination methods. We also explain effects of synthesis parameters on the size and quality of Ti3C2Tx and suggest the optimal processes for the desired application.
- 18Mashtalir, O.; Lukatskaya, M. R.; Zhao, M. Q.; Barsoum, M. W.; Gogotsi, Y. Amine-Assisted Delamination of Nb2C MXene for Li-Ion Energy Storage Devices. Adv. Mater. 2015, 27 (23), 3501– 3506, DOI: 10.1002/adma.20150060418https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnsFCltrs%253D&md5=ccb60c8d992d93a495989af04a405d86Amine-Assisted Delamination of Nb2C MXene for Li-Ion Energy Storage DevicesMashtalir, Olha; Lukatskaya, Maria R.; Zhao, Meng-Qiang; Barsoum, Michel W.; Gogotsi, YuryAdvanced Materials (Weinheim, Germany) (2015), 27 (23), 3501-3506CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)MXenes are stacks of 2D early transition metal carbides and carbonitrides of general formula Mn+1XnTx , where M stands for metal atom, X stands for C and/or N, n = 1, 2, or 3, and Tx represents various surface terminations (OH, O, and/or F groups). Delaminated MXenes can store more charge than their multilayer counterparts; introduction of carbon additives, such as carbon nanotubes (CNTs) into the electrode structure improves ion accessibility to the MXene layers and boosts both specific capacities and resulting rate performances. So far only Ti3C2Tx has been synthesized and tested in delaminated form. To delaminate the latter DMSO, DMSO, was used. In this Communication, our main goal is to report on the delamination of a second representative of the MXene family Nb2CTx using an amine instead of DMSO. The electrochem. behavior of delaminated Nb2CTx/CNT composite electrodes in Li-ion batteries and supercapacitors are superior to their multilayered counterparts.
- 19Naguib, M.; Unocic, R. R.; Armstrong, B. L.; Nanda, J. Large-Scale Delamination of Multi-Layers Transition Metal Carbides and Carbonitrides “MXenes.. Dalt. Trans. 2015, 44 (20), 9353– 9358, DOI: 10.1039/C5DT01247C19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXms1ygu7w%253D&md5=d9a88c056f39d4c0ef9a0921d58b6dacLarge-scale delamination of multi-layers transition metal carbides and carbonitrides "MXenes"Naguib, Michael; Unocic, Raymond R.; Armstrong, Beth L.; Nanda, JagjitDalton Transactions (2015), 44 (20), 9353-9358CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Herein we report on a general approach to delaminate multi-layered MXenes using an org. base to induce swelling that in turn weakens the bonds between the MX layers. Simple agitation or mild sonication of the swollen MXene in water resulted in the large-scale delamination of the MXene layers. The delamination method is demonstrated for vanadium carbide and titanium carbonitride MXenes.
- 20Holder, C. F.; Schaak, R. E. Tutorial on Powder X-Ray Diffraction for Characterizing Nanoscale Materials. ACS Nano 2019, 13 (7), 7359– 7365, DOI: 10.1021/acsnano.9b0515720https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtl2iu7%252FN&md5=1cc19bb0dce3776f4aefcb3eee6a308bTutorial on Powder X-ray Diffraction for Characterizing Nanoscale MaterialsHolder, Cameron F.; Schaak, Raymond E.ACS Nano (2019), 13 (7), 7359-7365CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review. The authors provide the broad nanoscience and nanotechnol. communities with a brief tutorial on some of the key aspects of powder XRD data that are often encountered when analyzing samples of nanoscale materials, with an emphasis on inorg. nanoparticles of various sizes, shapes, and dimensionalities.
- 21Ahmed, B.; Anjum, D. H.; Hedhili, M. N.; Gogotsi, Y.; Alshareef, H. N. H2O2 Assisted Room Temperature Oxidation of Ti2C MXene for Li-Ion Battery Anodes. Nanoscale 2016, 8 (14), 7580– 7587, DOI: 10.1039/C6NR00002A21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XjslKiur4%253D&md5=657228c1d37c6ff8c631b85e1113b98aH2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodesAhmed, Bilal; Anjum, Dalaver H.; Hedhili, Mohamed N.; Gogotsi, Yury; Alshareef, Husam N.Nanoscale (2016), 8 (14), 7580-7587CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidn. at room temp. when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) anal. We show that the reaction time and the amt. of hydrogen peroxide used are the limiting factors, which det. the morphol. and compn. of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepd. MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g-1, 337 mA h g-1 and 297 mA h g-1 were obtained for H2O2 treated MXene at current densities of 100 mA g-1, 500 mA g-1 and 1000 mA g-1, resp. In addn., when tested at a very high c.d., such as 5000 mA g-1, the H2O2 treated MXene showed a specific capacity of 150 mA h g-1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.
- 22Yuen, A. C. Y.; Chen, T. B. Y.; Lin, B.; Yang, W.; Kabir, I. I.; De Cachinho Cordeiro, I. M.; Whitten, A. E.; Mata, J.; Yu, B.; Lu, H. D.; Yeoh, G. H. Study of Structure Morphology and Layer Thickness of Ti3C2MXene with Small-Angle Neutron Scattering (SANS). Compos. Part C Open Access 2021, 5 (May), 100155, DOI: 10.1016/j.jcomc.2021.100155There is no corresponding record for this reference.
- 23Lipatov, A.; Lu, H.; Alhabeb, M.; Anasori, B.; Gruverman, A.; Gogotsi, Y.; Sinitskii, A. Elastic Properties of 2D Ti3C2Tx MXene Monolayers and Bilayers. Sci. Adv. 2018, 4 (6), 1– 8, DOI: 10.1126/sciadv.aat0491There is no corresponding record for this reference.
- 24Birkl, C. R.; Roberts, M. R.; McTurk, E.; Bruce, P. G.; Howey, D. A. Degradation Diagnostics for Lithium Ion Cells. J. Power Sources 2017, 341, 373– 386, DOI: 10.1016/j.jpowsour.2016.12.01124https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVKrs7rI&md5=9ceba52b3288d990c89f44dd5c2405afDegradation diagnostics for lithium ion cellsBirkl, Christoph R.; Roberts, Matthew R.; McTurk, Euan; Bruce, Peter G.; Howey, David A.Journal of Power Sources (2017), 341 (), 373-386CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)Degrdn. in lithium ion (Li-ion) battery cells is the result of a complex interplay of a host of different phys. and chem. mechanisms. The measurable, phys. effects of these degrdn. mechanisms on the cell can be summarised in terms of three degrdn. modes, namely loss of lithium inventory, loss of active pos. electrode material and loss of active neg. electrode material. The different degrdn. modes are assumed to have unique and measurable effects on the open circuit voltage (OCV) of Li-ion cells and electrodes. The presumptive nature and extent of these effects has so far been based on logical arguments rather than exptl. proof. This work presents, for the first time, exptl. evidence supporting the widely reported degrdn. modes by means of tests conducted on coin cells, engineered to include different, known amts. of lithium inventory and active electrode material. Moreover, the general theory behind the effects of degrdn. modes on the OCV of cells and electrodes is refined and a diagnostic algorithm is devised, which allows the identification and quantification of the nature and extent of each degrdn. mode in Li-ion cells at any point in their service lives, by fitting the cells' OCV.
- 25Kong, F.; He, X.; Liu, Q.; Qi, X.; Zheng, Y.; Wang, R.; Bai, Y. Improving the Electrochemical Properties of MXene Ti3C2Multilayer for Li-Ion Batteries by Vacuum Calcination. Electrochim. Acta 2018, 265, 140– 150, DOI: 10.1016/j.electacta.2018.01.19625https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVOqtLo%253D&md5=0d8c62eeed5a88a742709abc93b29247Improving the electrochemical properties of MXene Ti3C2 multilayer for Li-ion batteries by vacuum calcinationKong, Fanyu; He, Xiaodong; Liu, Qianqian; Qi, Xinxin; Zheng, Yongting; Wang, Rongguo; Bai, YueleiElectrochimica Acta (2018), 265 (), 140-150CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Ltd.)The electrochem. properties of MXene Ti3C2 multilayer for Li-ion batteries were improved greatly by vacuum calcination, after systematically evaluating its thermal stability in different atm. in details. In air, the as-prepd. Ti3C2 could not be oxidized up to 429.9° and the rutile-TiO2 would remain as the oxidn. product at 1200°. The surface functional groups esp. F groups can be eliminated by heat treatment. After vacuum calcination at 400°, the Ti3C2 show much higher capacities due to the removal of OH groups (126.4 mAh g-1 at 1C), and exhibited excellent rate capability. Besides, the formation of TiO2 nanoparticles at 700° further increases the 1st coulombic efficiency (62%) and capacity retention after 100 cycles (97%). In contrast, the dense microstructures of resulting TiCx formed after calcination at 1000° results in the worst electrochem. properties. This paper presented a relatively simple and easily scalable post-treatment for improving the electrochem. properties of MXene, and demonstrated a great potential of Ti3C2 of using as anode material for Li-ion batteries.
- 26Lv, G.; Wang, J.; Shi, Z.; Fan, L. Intercalation and Delamination of Two-Dimensional MXene (Ti3C2Tx) and Application in Sodium-Ion Batteries. Mater. Lett. 2018, 219, 45– 50, DOI: 10.1016/j.matlet.2018.02.01626https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtVCku70%253D&md5=0bb2edd37b1c9c9fae0e76dd875a689fIntercalation and delamination of two-dimensional MXene (Ti3C2Tx) and application in sodium-ion batteriesLv, Guoxia; Wang, Jing; Shi, Zhiqiang; Fan, LipingMaterials Letters (2018), 219 (), 45-50CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The initial multilayer-structure two-dimensional transition metal carbide MXene (as-Ti3C2Tx) were synthesized by selectively etching Mn+1AXn in HF, and the surface of MXene adhere to some functional groups. Intercalation and delamination by ultrasonication in alc. or DMSO produce less lamellar structure of resultant (d-Ti3C2Tx) and change the surface circumstance. This fabricated fewer-sheets samples not only improve the elec. conductibility, specific area, but also reduce the ion diffusion resistance. Meanwhile, the d-aTi3C2Tx and d-D-Ti3C2Tx show outstanding capacity of 110 or 120 mAh g-1 at 100 mA g-1 with coulombic efficiency of ∼95%, which lead to 26% increase compared with as-Ti3C2Tx (95 mAh g-1) for Na-ion batteries, and remarkable capacitance retention of 84.5% or 85.8% after cycles for in alc. and DMSO, resp.
- 27Xie, Y.; Naguib, M.; Mochalin, V. N.; Barsoum, M. W.; Gogotsi, Y.; Yu, X.; Nam, K. W.; Yang, X. Q.; Kolesnikov, A. I.; Kent, P. R. C. Role of Surface Structure on Li-Ion Energy Storage Capacity of Two-Dimensional Transition-Metal Carbides. J. Am. Chem. Soc. 2014, 136 (17), 6385– 6394, DOI: 10.1021/ja501520b27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXltFGlsbk%253D&md5=8a48485460db1c614d1ec6741da1120fRole of surface structure on Li-ion energy storage capacity of two-dimensional transition-metal carbidesXie, Yu; Naguib, Michael; Mochalin, Vadym N.; Barsoum, Michel W.; Gogotsi, Yury; Yu, Xiqian; Nam, Kyung-Wan; Yang, Xiao-Qing; Kolesnikov, Alexander I.; Kent, Paul R. C.Journal of the American Chemical Society (2014), 136 (17), 6385-6394CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)A combination of d. functional theory (DFT) calcns. and expts. is used to shed light on the relation between surface structure and Li-ion storage capacities of the following functionalized two-dimensional (2D) transition-metal carbides or MXenes: Sc2C, Ti2C, Ti3C2, V2C, Cr2C, and Nb2C. The Li-ion storage capacities are found to strongly depend on the nature of the surface functional groups, with O groups exhibiting the highest theor. Li-ion storage capacities. MXene surfaces can be initially covered with OH groups, removable by high-temp. treatment or by reactions in the first lithiation cycle. This was verified by annealing f-Nb2C and f-Ti3C2 at 673 and 773 K in vacuum for 40 h and in situ X-ray adsorption spectroscopy (XAS) and Li capacity measurements for the first lithiation/delithiation cycle of f-Ti3C2. The high-temp. removal of water and OH was confirmed using X-ray diffraction and inelastic neutron scattering. The voltage profile and X-ray adsorption near edge structure of f-Ti3C2 revealed surface reactions in the first lithiation cycle. Moreover, lithiated oxygen terminated MXenes surfaces are able to adsorb addnl. Li beyond a monolayer, providing a mechanism to substantially increase capacity, as obsd. mainly in delaminated MXenes and confirmed by DFT calcns. and XAS. The calcd. Li diffusion barriers are low, indicative of the measured high-rate performance. We predict the not yet synthesized Cr2C to possess high Li capacity due to the low activation energy of water formation at high temp., while the not yet synthesized Sc2C is predicted to potentially display low Li capacity due to higher reaction barriers for OH removal.
- 28Liu, L.; Lin, Z.; Chane-Ching, J. Y.; Shao, H.; Taberna, P. L.; Simon, P. 3D RGO Aerogel with Superior Electrochemical Performance for K – Ion Battery. Energy Storage Mater. 2019, 19, 306– 313, DOI: 10.1016/j.ensm.2019.03.013There is no corresponding record for this reference.
- 29Guan, Y.; Zhang, M.; Qin, J.; Ma, X.; Li, C.; Tang, J. Hydrophilicity-Dependent Distinct Frictional Behaviors of Different Modified MXene Nanosheets. J. Phys. Chem. C 2020, 124 (25), 13664– 13671, DOI: 10.1021/acs.jpcc.0c0155129https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVCrsLrI&md5=861dbac90d7c896caec69480dae5f36cHydrophilicity-Dependent Distinct Frictional Behaviors of Different Modified MXene NanosheetsGuan, Yanxue; Zhang, Miaomiao; Qin, Juan; Ma, Xingxing; Li, Chen; Tang, JilinJournal of Physical Chemistry C (2020), 124 (25), 13664-13671CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)MXene nanosheets are promising to be ultrathin solid lubricant or interface solving the friction and wear problems of miniaturized equipment. Here, the frictional behaviors and adhesive properties of the Ti3C2, F-Ti3C2, and TMA-Ti3C2 nanosheets were explored by at. force microscope for the first time. The nanofrictional behavior of TMA-Ti3C2 was significantly different from that of Ti3C2 and F-Ti3C2. The friction of TMA-Ti3C2 increased slightly and then decreased as the load decreased, leading to the appearance of a neg. friction factor; the frictions of Ti3C2 and F-Ti3C2 decreased with decreasing load, resulting in pos. friction factors. Meanwhile, because the surface of TMA-Ti3C2 was more hydrophilic than that of Ti3C2 and F-Ti3C2, the friction and adhesion of TMA-Ti3C2 were greater than those of Ti3C2 and F-Ti3C2. It indicated that the surface properties played an important role in the adhesion and friction. Hence, adjusting the surface properties of MXene nanosheets will provide a new direction for designing solid lubricants and nanointerfaces in micro- and nanoelectromech. systems.
- 30Liu, J.; Liu, Z.; Zhang, H. B.; Chen, W.; Zhao, Z.; Wang, Q. W.; Yu, Z. Z. Ultrastrong and Highly Conductive MXene-Based Films for High-Performance Electromagnetic Interference Shielding. Adv. Electron. Mater. 2020, 6 (1), 1– 8, DOI: 10.1002/aelm.201901094There is no corresponding record for this reference.
- 31Wang, P.; Lu, X.; Boyjoo, Y.; Wei, X.; Zhang, Y.; Guo, D.; Sun, S.; Liu, J. Pillar-Free TiO2/Ti3C2 Composite with Expanded Interlayer Spacing for High-Capacity Sodium Ion Batteries. J. Power Sources 2020, 451, 227756, DOI: 10.1016/j.jpowsour.2020.22775631https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtlajurs%253D&md5=7ecde58494a71e12d91aa162dca3dcb4Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing for high-capacity sodium ion batteriesWang, Peiyuan; Lu, Xiaoxuan; Boyjoo, Yash; Wei, Xiaorong; Zhang, Yonghui; Guo, Dongjie; Sun, Shumin; Liu, JianJournal of Power Sources (2020), 451 (), 227756CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)The lamellar transition metal oxides, sulfides and carbides with expanded interlayer spacing have attracted wide attention due to their enlargeable interlayer diffusion channels and larger contact areas. However, the existence of pillars between the interlayer would occupy the inter layer voids, which would hinder the accommodation of more Li ion, Na ion and so on. Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing was prepd. by sintering the pre-intercalated pristine Ti3C2 with TMAOH under N2 atmosphere. The obtained TiO2/Ti3C2 composite showed remarkable capacity (237.8 mA-h g-1 at 100 mA g-1) and long-term stability (153 mA-h g-1after 100 cycles at c.d. of 600 mA g-1) as anode material for Na ion batteries. These remarkable electrochem. properties of pillar-free TiO2/Ti3C2 were ascribed to its effective expanded interlayer distance fixed by TiO2 nanoparticles attached on the edge plane of Ti3C2, pseudocapacitance contribution of TiO2 nanoparticles, and the synergistic effect between TiO2 and Ti3C2. This work offered a general strategy for fabricating pillar-free MXene-based composites with enlarged interlayer spacing.
- 32Arole, K.; Blivin, J. W.; Saha, S.; Zhao, X.; Holta, D. E.; Sarmah, A.; Cao, H.; Radovic, M.; Lutkenhaus, J. L.; Green, M. J. Water-Dispersible Ti 3C 2T z MXene Nanosheets by Acid-Free, Molten Salt Etching. Cell Press 2021, 1 (2), 35There is no corresponding record for this reference.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsnano.1c08498.
Additional experimental data such as EDS, TEM, and electrochemical properties of the pristine and TMAOH-treated MS-Ti3C2 MXenes (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
