二元酚低共熔溶剂辅助制备TiO₂
Diphenol eutectic solvent-assisted preparation of TiO2

摘要：本文利用氯化胆碱和二元酚合成低共熔剂（DES），采用溶胶-凝胶法制备出对红外光具有响应性的黑色缺陷C/TiO₂复合光催化剂。以研究羟基位置和EDS用量对催化剂性能的影响。催化剂的表征结果表明，低共熔剂（DES）对TiO2氢键力和结构性能影响起着至关重要作用。具体来说，受DES模板影响，TiO2产生大量氧缺陷，光响应区由紫外扩到可见光。光催化性能表明，对位羟基的作用最好，ChCl/H-TiO₂具有高碳含量，表现出更强的光吸收和抑制电子-空穴复合速率的能力，在光催化降解MB溶液的测试中，是纯TiO₂的9.57倍，循环稳定性好；其次，DES: Ti = 1.0时最佳催化性能得到改善，在120 min内的降解率为97.0%。
Abstract:In this paper, eutectic agent (DES) was synthesized by choline chloride and diphenols, and prepared by sol-gel method A black-defective C/TiO2 composite photocatalyst that is responsive to infrared light is produced. to study the effects of hydroxyl position and EDS dosage on catalyst performance. The characterization results of the catalyst showed that eutectic agent (DES) plays a crucial role in the influence of TiO2 hydrogen bonding force and structural properties. Specifically, under the influence of the DES template, TiO2 produces a large number of oxygen defects, and the light response region expands from ultraviolet to visible light. The photocatalytic performance showed that the para-hydroxyl group had the best effect, and ChCl/H-TiO2 had a high carbon content and exhibited stronger light absorption and electron-inhibitionThe ability of the hole recombination rate, in the test of photocatalytic degradation of MB solution, is 9.57 times higher than that of pure TiO2, Good cyclic stability; Secondly, the optimal catalytic performance was improved when DES: Ti = 1.0, and the degradation rate was 97.0% within 120 min.

1.介绍
1. Introduction

未经处理的染料废水中含有大量的有机染料、助剂、添加剂、酸碱度调节剂等。有机染料结构复杂，大多含有难以降解的杂环或者芳香类化合物，难以净化 ^[10]。利用新型可再生能源来开发环保的污染防治技术，太阳能是一种丰富而可再生的能源。然而，其广泛利用仍受到技术瓶颈的制约。因此，开发新技术和材料提高太阳能利用率对于能源安全和环境保护至关重要。通过运用光催化剂，在光照下激发催化剂表面的电子形成光生电子和空穴，促使发生化学反应，高效地降解水中的有机污染物^[11–13]，清理空气中的污染物^[14–16]，并且有望成为清洁能源（如H₂^[22,21]、CH₄^[19]等）生产的重要途径。光催化剂的种类多种多样，其化学成分直接影响着其光催化性能和应用范围。经过多年的研究，已经有多种物质被证明具有光催化性能，包括过渡金属氧化物（TiO₂^[15]、ZnO^[20]、Fe₂O₃^[21]、V₂O₅^[22]），硫化物（ZnS^[23]、MoS₂^[24]、CdS^[25]），氮化物（g-C₃N₄^[26,27]、TiN^[28]）等以及它们的改性或者复合产物。不同催化剂对光的吸收范围、催化活性、选择性、稳定性和生产成本等方面有所不同。TiO₂作为n型半导体，表现出介于导体和绝缘体之间的性质，其具有特殊的能带结构^[32]，电子之间的运动呈相互关联状态；TiO₂晶体结构对其性能具有重要影响，其禁带宽度大小介于3.0~3.2 eV之间，主要的晶体结构包括锐钛矿相（anatase，3.2 eV）、金红石相（rutile，3.0 eV）和板钛矿相（brookite，3.2 eV）。在光催化反应期间光生电子和空穴的快速复合导致反应效率低。因此，为提高TiO2对污染物的光降解效率，人们提出了许多催化剂改性策略，以扩展其吸收到可见光范围并促进电荷分离，例如掺杂其他元素、构建异质结和染料光敏化等。
Untreated dye wastewater contains a large number of organic dyes, additives, additives, pH regulators, etc. Organic dyes have complex structures and mostly contain heterocyclic or aromatic compounds that are difficult to degrade and are difficult to purify ^[10]. Using new renewable energy sources to develop environmentally friendly pollution prevention and control technologies, solar energy is an abundant and renewable energy source. However, its widespread use is still constrained by technical bottlenecks. Therefore, the development of new technologies and materials to improve the utilization rate of solar energy is essential for energy security and environmental protection. By using photocatalysts, electrons on the surface of the catalyst are excited under light to form photogenerated electrons and holes, which promote chemical reactions to efficiently degrade organic pollutants in water ^[11–13] and clean up pollutants in the air^[14–16] and is expected to be a clean energy source (e.g., _H2 ^[22,21], CH₄ ^[19], etc.). There are various types of photocatalysts, and their chemical composition directly affects their photocatalytic performance and application range.After years of research, a variety of substances have been shown to have photocatalytic properties, including transition metal oxides (TiO2^[15], ZnO^[20]、Fe₂O₃^[21]、V₂O₅^[22]), sulfides (ZnS^[23], MoS2^[24]). , ^CdS[25]), nitride (g-C3N₄ ^[26,27], TiN ^[28]), etcThey are modified or compounded products. Different catalysts have different light absorption ranges, catalytic activity, selectivity, stability, and production costs. As an n-type semiconductor, TiO2 exhibits properties between conductors and insulators, and it has a special band structure ^[32]., the motion between electrons is interrelated; The crystal structure of TiO2 has an important impact on its performance, and its band gap width is between 3.0~3.2 eV. The main crystal structures include anatase (3.2 eV), rutile (rutile, 3.0 eV) and Brookite (3.2 eV). During the photocatalytic reaction, the rapid recombination of photogenerated electrons and holes leads to low reaction efficiency. Therefore, in order to improve the photodegradation efficiency of TiO2 to pollutants, many catalyst modification strategies have been proposed to extend its absorption to the visible light range and promote charge separation, such as doping other elements, constructing heterojunctions, and dye photosensitization.

改性策略提升光催化性能，但在其合成和改性中使用有毒、刺激性和挥发性的石油基溶剂是一个不可忽视的问题，因此寻找一种高效无污染的溶剂是改性TiO₂的一个重点方向。低共熔溶剂（DES）近年来被广泛研究，因为它具有相对简单的制备程序和可以来源于天然、可生物降解和可持续来源的多种低成本低毒甚至无毒的组成组分，已在包括溶胶-凝胶、水热、溶剂热、离子热、湿化学和电化学等多种光催化剂制备方法中进行应用。根据DES在这些制备方法中发挥的主要作用进一步分类，DES可以是作为"设计型溶剂"或电解质介质。在制备光催化剂中如Shahi等^[121]引入了DES（ChCl/对甲苯磺酸）作为溶胶-凝胶反应形成混合相（锐钛矿-金红石）纳米晶TiO2的替代模板剂，进一步证实了DES作为生长控制剂的作用；Jia等^[124]通过使用胆碱磷酸/尿素DES的电解策略成功合成了N-P共掺杂的TiO₂，并强调了DES在电荷转移中的高效性，还证明了利用DES基纯有机溶液作为电解质制备非金属共掺杂窄带隙二氧化钛的可行性。
The modification strategy improves the photocatalytic performance, but the use of toxic, irritating and volatile petroleum-based solvents in its synthesis and modification is a problem that cannot be ignored, so the search for an efficient and pollution-free solvent is modified TiO2a key direction. Eutectic solvent (DES) has been widely studied in recent years because of its relatively simple preparation procedures and a variety of low-cost, low-toxicity or even non-toxic components that can be derived from natural, biodegradable and sustainable sources, and has been used in the inclusion of sols- It is used in a variety of photocatalyst preparation methods such as gel, hydrothermal, solvothermal, ionic thermal, wet chemistry and electrochemistry. Further classified according to the primary role played by DES in these preparation methods, DES can be used as a "design solvent".or electrolyte medium. In the preparation of photocatalysts, such as Shahi et al. ^[121], DES (ChCl/ p-toluenesulfonic acid) as an alternative template for the formation of mixed-phase (anatase-rutile) nanocrystalline TiO2 by sol-gel reactions, The role of DES as a growth control agent was further confirmed; Jia et al. ^{[124] used} choline phosphate/urea DESThe N-P co-doped TiO2 was successfully synthesized and the high efficiency of DES in charge transfer was emphasizedThe feasibility of using DES-based pure organic solution as an electrolyte to prepare non-metallic co-doped narrow bandgap titanium dioxide was also demonstrated.

本研究以氯化胆碱（ChCl）作HBA，改变HBD种类和合成后EDS比例，以三种二元酚邻苯二酚（C），对苯二酚(H)和间苯二酚(R)分别为HBD，利用溶胶-凝胶法通过DES作为溶剂和碳源辅助合成TiO₂，采用SEM、XPS、EPR、UV-Vis和光催化降解实验等多种表征手段对材料进行表征，探究苯环和羟基位置对合成TiO₂的影响以及EDS比例对光催化性能的影响。
In this study, choline chloride (ChCl) was used as HBA, and the type and synthesis of HBD were changedEDS ratios were divided into three diphenols, catechol (C), hydroquinone (H) and resorcinol (R).HBD, using the sol-gel method to assist in the synthesis of TiO2 by DES as a solvent and carbon source, using SEM, XPS, EPR,A variety of characterization methods such as UV-Vis and photocatalytic degradation experiments were used to characterize the materials, and the effects of benzene ring and hydroxyl group positions on the synthesis of TiO2 were explored Effect of EDS ratio on photocatalytic performance.

2.实验和表征
2. Experiments and characterization

2.1 实验试剂和仪器
2.1 Experimental reagents and instruments

实验所需试剂包括氯化胆碱、邻苯二酚、间苯二酚、对苯二酚、钛酸四丁酯、亚甲基蓝、硝酸、无水乙醇和纯水。以上所有试剂均为AR级，但水为UP级。除纯水外，所有试剂均来自成都市科龙化工试剂厂。实验所需设备有电子天平（HX-T，浙江天东仪器厂）、电热恒温干燥箱（DHG-9077A;上海景宏实验设备有限公司）、磁力搅拌器（84-1A;广州航鑫科技设备有限公司）、超纯水机（UPR-l;四川优普超纯科技有限公司）、马弗炉（SX-G07123；天津中环电炉股份有限公司）、可见光分光光度计（V1800;上海美派达仪器有限公司）、高速旋转离心机（TGL-16gR;上海安亭科学仪器厂）、电热鼓风干燥箱（101-OAB;天津泰斯特仪器有限公司）、光学暗箱（GXAS345；北京纽比特科技有限公司）、节能箱式电炉（SX-G07123;天津中环电炉有限公司）及氙灯及配套设施（LED/75W;氙灯的有效光谱范围为185nm-2000nm;杭州曲豪贸易有限公司）。
The reagents required for the experiment include choline chloride, catechol, resorcinol, hydroquinone, etcTetrabutyl titanate, methylene blue, nitric acid, absolute ethanol and purified water. All of the above reagents are AR grade, but water is UP grade. Except for pure water, all reagents are from Chengdu Kelon Chemical Reagent Factory. The equipment required for the experiment includes electronic balance (HX-T, Zhejiang Tiandong Instrument Factory), electric constant temperature drying oven (DHG-9077A; Shanghai Jinghong Experimental Equipment Co., Ltd.), magnetic stirrer (84-1A; Guangzhou Hangxin Technology Equipment Co., Ltd.), ultrapure water machine (UPR-l; Sichuan Youpu Ultrapure Technology Co., Ltd.), Muffle furnace (SX-G07123; Tianjin Zhonghuan Electric Furnace Co., Ltd.), visible light spectrophotometer (V1800; Shanghai Meipaida Instrument Co., Ltd.), high-speed rotary centrifuge (TGL-16gR; Shanghai Anting Scientific Instrument Factory), Electric Blower Drying Oven (101-OAB; Tianjin Tester Instrument Co., Ltd.), optical chamber (GXAS345; Beijing Newbit Technology Co., Ltd.), energy-saving box-type electric furnace (SX-G07123; Tianjin Zhonghuan Electric Furnace Co., Ltd.) and xenon lamps and supporting facilities (LED/75W; The effective spectral range of xenon lamps is 185nm-2000nm; Hangzhou Quhao Trading Co., Ltd.).

2.2 催化剂制备
2.2 Catalyst preparation

（a）二元酚DES的制备
(a) Preparation of diphenol DES

以氯化胆碱为氢键受体HBA,然后分别以邻苯二酚，对苯二酚和间苯二酚作为氢键供体HBD，分别取一定的量按照HBA : HBD = 1 : 2（M）放入250 mL烧瓶中，80 ℃磁力搅拌至溶液变澄清透明，ChCl/H、ChCl/C和ChCl/R三种DES合成成功。
Choline chloride was used as the hydrogen bond acceptor HBA, and then catechol, hydroquinone and resorcinone were used as hydrogen bond donors HBD, and a certain amount was taken according to HBA: HBD = 1:2(M) Put it in a 250 mL flask and stir magnetically at 80 °C until the solution becomes clear and transparent. ChCl/H, ChCl/C and ChCl/R were successfully synthesized.

（b）C/TiO₂的制备
(b) Preparation of C/TiO2

采用溶胶-凝胶法制备C/TiO2复合光催化剂，具体实验步骤如下：
The C/TiO2 composite photocatalyst was prepared by sol-gel method, and the specific experimental steps are as follows

首先，将0.025 mol钛酸四丁酯（TBT）缓慢溶解加入无水乙醇中，经过磁力搅拌直至溶液均匀透明，得到A溶液；接着，将0.05 mol相应的DES加入装有无水乙醇和纯水的烧杯中，通过加入硝酸调节pH值至3~4，经过磁力搅拌使DES完全分散，得到B溶液。在磁力搅拌的作用下，缓慢将溶液B滴加到溶液A中，使得TBT缓慢水解。滴加完成后，继续搅拌1 h形成白色溶胶。在室温下静置6 h后放入烘箱进行干燥，在70 ℃下烘干12 h，干燥后研磨成粉末，并在马弗炉中400 ℃煅烧2 h，制得C/TiO2复合介孔材料。为了找出DES种类对TiO2光催化性能的影响，通过改变DES的种类合成了一系列TiO2，加入氯化胆碱ChCl和邻苯二酚，对苯二酚，间苯二酚作为氢键供体HBD制成的DES的TiO2样品分别命名为ChCl/H-TiO2、ChCl/C-TiO2、ChCl/R-TiO2。为了对比改性效果，制备了一组在B溶液中不加DES的纯TiO2样品，命名为TiO2。
Firstly, 0.025 mol tetrabutyl titanate (TBT) was slowly dissolved and added into absolute ethanol, and the solution was obtained after magnetic stirring until the solution was uniform and transparent. Then, 0.05 mol of the corresponding DES was added to a beaker filled with absolute ethanol and pure water, and the pH value was adjusted to 3~4 by adding nitric acidAfter magnetic stirring, DES was completely dispersed to obtain B solution. Under the action of magnetic stirring, solution B is slowly added dropwise to solution A, so that TBT is slowly hydrolyzed. After the dropwise addition is completed, continue to stir for 1 h to form a white sol. After standing at room temperature for 6 h, it was placed in an oven for drying, dried at 70 °C for 12 h, dried and ground into powder, and placed in a muffle furnace for 400 °C C/TiO2 composite mesoporous materials were prepared by calcination at °C for 2 h. In order to find out the effect of DES species on the photocatalytic performance of TiO2, a series of TiO2 were synthesized by changing the DES species. Choline chloride ChCl and catechol, hydroquinone, resorcinol are added as hydrogen bond donors The TiO2 samples of DES made by HBD were named ChCl/H-TiO2, respectively 、ChCl/C-TiO2、ChCl/R-TiO2。 In order to compare the modification effect, a group of pure TiO2 samples without DES in B solution were prepared, named TiO2.

（c）不同用量EDS的C/TiO2制备
(c) Preparation of C/TiO2 with different dosages of EDS

探究不同DES用量对TiO₂光催化性能的影响时，取上述最佳降解效率HBD制备的EDS，煅烧温度控制在400 ℃，煅烧气氛为空气，设置DES：Ti（M）四个用量梯度。并将催化剂分别命名为0.5 ChCl/X-TiO₂、1.0 ChCl/X-TiO₂、2.0 ChCl/X-TiO₂、3.0 ChCl/X-TiO₂。
When exploring the effects of different DES dosages on the photocatalytic performance of TiO2, the above HBD with the best degradation efficiency was taken The calcination temperature of the prepared EDS was controlled at 400 °C, and the calcination atmosphere was set as airDES: Ti(M) four dosage gradients. The catalysts were named as 0.5 ChCl/X-TiO2 and 1.0 ChCl/X, respectively -TiO₂、2.0 ChCl/X-TiO₂、 3.0 ChCl/X-TiO₂。

2.3 C/TiO2的表征
2.3 Characterization of C/TiO2

首先扫描电子显微镜（SEM）（Thermo scientific Apreo 2C）对催化剂的形貌特征进行了扫描，并使用真空喷金操作，在5 kV的操作电压下获取了具有代表性的形貌图片以及EDS能谱测试得到的催化剂元素组成等信息。接着，采用X射线衍射仪（XRD）（X.PERT PRO）配备Cu靶和Kα辐射源对催化剂的晶相结构进行了分析，样品研磨成10 μm左右的颗粒后，在40 kV、40 mA的条件下进行了10°~80°的扫描角度范围内的测试。同时，采用X射线光电子能谱（XPS）（ESCALAB 250Xi）进行了样品表面元素信息的分析，工作电压12.5 kV，灯丝电流16 mA，Al kα射线（hv = 1486.6 eV）作为激发源，所有结合能均以C 1s峰284.6 eV为参考基准。紫外可见漫反射光谱（UV-vis DRS）（PerkinEImer Lambda Model 850）在200 nm~800 nm波长范围内使用BaSO₄作为空白对照进行了校正，并检查了样品的能级结构和光吸收特性。再用紫外可见近红外分光光度计（UV/VIS/NIR）（Lambda 1050）测定催化剂对200~2500nm的光谱吸收性能。此外，荧光光谱测试（PL）（Hitachi F-7000 DC-0506）以λ = 300 nm进行激发，获得了样品的荧光光谱信息。还有，通过红外光谱（FT-IR）（北京瑞利分析仪器有限公司WQF520型）分析催化剂的特征官能团等信息。样品经过研磨、干燥、压片后进行检测。电子自旋共振波谱仪（ESR/EPR）（布鲁克EMX-PLUS）用以检测催化剂中可能存在的氧空位，Ti³⁺等缺陷。之后，采用利用氮气吸附-脱附等温线（BET）（ST-MP-9）评估了样品的比表面积、孔径分布和孔容量，在423 K条件下在FLOVAC装置中进行了3小时真空脱气，并且采用Brunauer-Emmett-Teller方程获取表面积，Barrett-Joyner-Halenda模型确定孔径分布和平均孔径。最后，通过热重-质谱联用（TG-MS）（耐驰 STA449 -耐驰 QMS403）对催化剂煅烧过程的热分解行为加以分析。
The topography of the catalyst was first scanned by scanning electron microscopy (SEM) (Thermo scientific Apreo 2C) and performed using a vacuum gold spray operation at 5 kVAt the operating voltage, representative morphology pictures and the elemental composition of the catalyst obtained by EDS spectroscopy were obtained. Next, an X-ray diffractometer (XRD) (X.PERT PRO) was equipped with a Cu target andThecrystalline phase structure of the catalyst was analyzed α the radiation source, and the sample was ground into particles of about 10 μm at 40 kVThe test was carried out under the condition of 40 mA in the range of 10°~80° scanning angle. At the same time, X-ray photoelectron spectroscopy (XPS) (ESCALAB 250Xi) was used to analyze the elemental information on the surface of the sample, and the working voltage was 12.5 kV, filament current 16 mA, Al kα ray (hv = 1486.6 eV) as the excitation source, all binding energies are used asThe C 1s peak of 284.6 eV was used as a reference reference. Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) (PerkinEImer Lambda Model 850) is used in the wavelength range of 200 nm~800 nm_BaSO4 was corrected as a blank control, and the energy level structure and light absorption characteristics of the samples were examined. Then, the spectral absorption performance of the catalyst at 200~2500nm was determined by ultraviolet-visible near-infrared spectrophotometer (UV/VIS/NIR) (Lambda 1050). In addition, the fluorescence spectral test (PL) (Hitachi F-7000 DC-0506) was excited at λ = 300 nm to obtain the fluorescence spectral information of the sample. In addition, infrared spectroscopy (FT-IR) (Beijing Rayleigh Analytical Instrument Co., Ltd. WQF520) was used to analyze the characteristic functional groups and other information of the catalyst.Samples are ground, dried, tableted and tested. Electron spin resonance spectrometer (ESR/EPR) (Bruker EMX-PLUS).It is used to detect possible defects such as oxygen vacancies and Ti³⁺ in the catalyst. Subsequently, the specific surface area, pore size distribution, and pore volume of the samples were evaluated using a nitrogen adsorption-desorption isotherm (BET) (ST-MP-9) at 423 KVacuum degassing was performed in a FLOVAC unit for 3 hours, and the surface area was obtained using the Brunauer-Emmett-Teller equation. The Barrett-Joyner-Halenda model determines the pore size distribution and the average pore size. Finally, by thermogravimetry-mass spectrometry (TG-MS) (NETZSCH STA449 - NETZSCH QMS403) to analyze the thermal decomposition behavior of the catalyst calcination process.

2.4光催化性能评价
2.4 Evaluation of photocatalytic performance

在自制的光催化降解装置中，使用亚甲基蓝（MB）溶液（20 mg/L）作为模拟废水，在遮光条件下进行了实验。利用可见光源（75 W的氙灯）对亚甲基蓝溶液进行了光催化降解实验的过程如下：
In a self-made photocatalytic degradation device, methylene blue (MB) solution (20 mg/L) was used as simulated wastewater and experiments were carried out under shading conditions. The photocatalytic degradation of methylene blue solution using a visible light source (75 W xenon lamp) was carried out as follows

在石英烧杯中量取50 mL MB溶液，并加入0.1 g二氧化钛（TiO₂），在磁力搅拌器的搅拌下，在遮光条件下搅拌30分钟，使其达到吸附-脱附平衡。
Measure 50 mL of MB solution in a quartz beaker and add 0.1 g of titanium dioxide (TiO2), Stir for 30 min under shading conditions under the stirrer of a magnetic stirrer to reach adsorption-desorption equilibrium.

开始光照后，通过打开氙灯进行2小时的光催化降解实验。
After initiating the light, perform a 2-h photocatalytic degradation experiment by turning on the xenon lamp.

每20分钟取出6 mL水样，并将其离心1分钟（离心速度5000 r/min），取上清液用分光光度计测试其吸光度。
6 mL of water sample was removed every 20 minutes and centrifuged for 1 minute (centrifugation speed 5000 r/min). Take the supernatant and test its absorbance with a spectrophotometer.

测试结束后，将水样倒回原烧杯中继续实验，并重复相同的程序。
At the end of the test, pour the water sample back into the original beaker to continue the experiment and repeat the same procedure.

这一系列步骤构成了光催化降解实验的操作流程，旨在评估催化剂对模拟废水中有机染料的光催化降解性能。
This series of steps constitutes the operation of the photocatalytic degradation experiment, which aims to evaluate the photocatalytic degradation performance of the catalyst for organic dyes in simulated wastewater.

然后采用公式（2-1）计算亚甲基蓝溶液的降解率，公式（2-2）用于计算降解过程拟一级动力学常数。
Then, equation (2-1) is used to calculate the degradation rate of methylene blue solution, and equation (2-2) is used to calculate the quasi-first-order kinetic constant of the degradation process.

  （2-1）

式中 η——MB的降解率，%；
where η - degradation rate of MB, %;

A₀——MB的初始浓度，mg/L；
A0 - initial concentration of MB, mg/L;

A_t——t时刻MB的浓度，mg/L。
A_t - the concentration of MB at time t, mg/L。

  （2-2）

式中 k——动力学常数，min^-1；
where k is the kinetic constant, ^min-1;

C₀——初始时刻MB溶液浓度，mg/L；
C₀ - the concentration of MB solution at the initial moment, mg/L;

C_t——t时刻MB溶液浓度，mg/L；
C_t - MB solution concentration at t time, mg/L；

t——时间，min。
t - time, min.

2.5光催化活性物种检测
2.5 Detection of photocatalytic active species

在光催化反应的机理解释中，检测和分析活性物种至关重要。在研究体系中，关键活性物种包括空穴（h⁺）、超氧自由基（•O₂⁻）和羟基自由基（•OH）。通过引入三乙醇胺（TEA）、对苯醌（BQ）和异丙醇（IPA）这三种捕获剂到光催化反应中，来捕获这些活性物种。然后，使用2.4中描述的方法来评估反应体系的降解率，并将其与未加入捕获剂时的降解率进行对照。如果加入捕获剂后的光催化降解率显著下降，表明该捕获剂所对应的活性物种为主要活性物种；如果下降幅度较小，则说明它是次要活性物种；如果没有下降，则说明该捕获剂所对应的活性物种并不是该光催化体系的关键活性物种。通过这种方法，能够推断出在光催化反应中起主要作用的活性物种，并进一步分析光催化反应的机理。
In the mechanistic interpretation of photocatalytic reactions, the detection and analysis of active species is crucial. In the research system, the key active species include holes (H⁺), superoxide radicals (•_O2^−). ) and hydroxyl radicals (•OH). These active species are captured by introducing three traps, triethanolamine (TEA), p-benzoquinone (BQ), and isopropanol (IPA), into the photocatalytic reaction. Then, use 24 to evaluate the degradation rate of the reaction system and compare it with the degradation rate without the addition of the trap. If the photocatalytic degradation rate decreases significantly after the addition of the trapper, it indicates that the active species corresponding to the trap agent is the main active species. If the decline is small, it is a minor active species; If there is no decrease, it means that the active species corresponding to the trap agent is not the key active species of the photocatalytic system. In this way, the active species that play a major role in the photocatalytic reaction can be inferred and the mechanism of the photocatalytic reaction can be further analyzed.

2.6 光催化剂循环使用稳定性
2.6 Cycling stability of photocatalysts

催化剂的循环使用性是评价催化剂总体性能是否优异的一个重要指标，在实验中通过多次回收循环再使用催化剂，并通过目标污染物MB的降解率来体现。在每次光催化降解MB实验操作结束后，通过多次水洗再离心，最后干燥这一系列操作将催化剂进行回收，并按照2.4中相同的实验流程用于下一次光催化实验，以此考察光催化剂的循环使用稳定性。
The recyclability of the catalyst is an important indicator to evaluate whether the overall performance of the catalyst is excellent, and the catalyst is recycled and reused through multiple times in the experiment, and it is reflected by the degradation rate of the target pollutant MB. At the end of each photocatalytic degradation MB experiment, the catalyst was recovered through multiple water washing, centrifugation, and finally drying, and used in the next photocatalytic experiment according to the same experimental procedure in 2.4, so as to investigate the cycling stability of the photocatalyst.

3.结果与分析
3. Results and Analysis

3.1 结构分析
3.1 Structural Analysis

3.1.1XRD分析
3.1.1XRD analysis

图1 TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂的XRD图谱
Fig.1. TiO2, ChCl/C-TiO2, XRD of ChCl/H-TiO2 and ChCl/R-TiO2Atlas

图1显示了纯TiO₂和使用三种二元酚作为HBD的DES制备的TiO₂催化剂的X射线衍射光谱。可以看到，2θ = 25.3°、37.7°、47.9°、53.9°、55.1°、62.6°、68.4°和70.5°与标准卡片（PDF 21-1272）一致，对应晶面(101)、(004)、(200)、(105)、(211)、(204)、(116)和(220)，表明在本实验中采用不同比例的DES制备的TiO₂均为锐钛矿型TiO₂。没有观察到碳的特征峰，可能是因为与25.3°的峰重合了。可以看出，二元酚中两个羟基位置的不同会导致TiO₂的结晶度不同。利用Scherrer方程（式2-1）从TiO₂衍射峰确定了催化剂的颗粒大小。TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂的粒径分别为24.24、7.66、6.38和5.68 nm，从纯TiO₂的24.24 nm减小到5.68 nm。TiO₂结晶度大小为TiO₂ > ChCl/R-TiO₂ > ChCl/C-TiO₂ > ChCl/H-TiO₂，总体而言三种改性催化剂的结晶度都比较低。由计算结果可见，二元酚基DES作为模板剂在一定程度上能够减小粒子大小。
Figure 1 shows pure TiO2 and the use of three diphenols as HBDX-ray diffraction spectra of a TiO2 catalyst prepared by DES. As you can see, 2θ = 25.3°, 37.7°, 47.9°, 53.9°, 55.1°, 62.6°, 68.4° and 70.5°Consistent with standard card (PDF 21-1272), corresponding to crystal planes (101), (004), (200) , (105), (211), (204), (116), and(220), indicating that the TiO2 prepared by different proportions of DES in this experiment were all anatase typeTiO₂。 No characteristic peaks of carbon were observed, probably because they coincided with the 25.3° peak. It can be seen that the difference in the position of the two hydroxyl groups in the diphenols leads to a different degree of crystallinity of TiO2. Using the Scherrer equation (Equation 2-1) from TiO2The diffraction peaks determine the particle size of the catalyst. TiO₂、ChCl/C-TiO₂、ChCl/H-TiOThe particle sizes of ₂ and ChCl/R-TiO2 were 24.24, 7.66, 6.38 and 5.68 nm from pure TiO₂of 24.24 nm decreased to 5.68 nm. The crystallinity of TiO2 was TiO2%3E ChCl/R-TiO₂ > ChCl/C-TiO2 > ChCl/H-TiO2, in general, the crystallinity of the three modified catalysts was relatively low. From the calculation results, it can be seen that the diphenol DES can reduce the particle size to a certain extent as a templating agent.

3.1.2 SEM分析
3.1.2 SEM analysis

图2是采用溶胶-凝胶法获得的纯TiO₂和ChCl/H-TiO₂的扫描电子显微镜（SEM）图像。从图2（a）可以看出，未添加DES作为模板合成的纯TiO₂是由TiO₂纳米颗粒聚集形成的团聚体，颗粒分散较差。聚集的原因是在水解过程中，TBT的水解速率过快，水解聚合物无法在乙醇中溶解，并直接进行快速的缩聚反应。然而，从图2（b）中可以看出虽然ChCl/H-TiO₂的颗粒还是出现了团聚现象，但由于ChCl/H的阻隔作用，合成的ChCl/H-TiO₂明显要比TiO₂的颗粒小很多，这无疑增大了ChCl/H-TiO₂的比表面积，加强了ChCl/H-TiO₂的反应型。
Figure 2 shows the pure TiO2 and ChCl/ obtained by the sol-gel method. Scanning electron microscopy (SEM) image of H-TiO2. As can be seen in Figure 2(a), DES is not added as a template for the synthesis of pure TiO₂ is an aggregate formed by the aggregation of TiO2 nanoparticles, and the particles are poorly dispersed. The reason for the aggregation is that during the hydrolysis process, the hydrolysis rate of TBT is too fast, and the hydrolyzed polymer cannot be dissolved in ethanol and directly undergoes a rapid polycondensation reaction. However, as can be seen from Figure 2(b), although ChCl/H-TiO2The particles still showed agglomeration, but due to the blocking effect of ChCl/H, the synthesized ChCl/H-TiO2 was significantly higherThe particles of TiO2 are much smaller, which undoubtedly increases the specific surface area of ChCl/H-TiO2 and strengthens ChCl/ Reactive type of H-TiO2.

图2 TiO₂和ChCl/H-TiO₂的SEM图谱
Figure 2 TiO2 and ChCl/H-TiO2SEM profiles

3.1.3 XPS分析
3.1.3 XPS Analysis

使用图3中描述的XPS图谱分析催化剂的表面元素组成和价态。图3（a）、（b）、（c）和（d）分别为TiO₂和ChCl/H-TiO₂催化剂的总谱图和C 1s、Ti 2p和O 1s分谱谱图。（a）中显示催化剂都包含Ti、O和C的特征峰。从（b）可以看出两种催化剂皆有三个碳峰，284.8 eV的结合能用作校正XPS图谱，按照结合能从小到大（下同）可以归结为C-C、C-O和C=O的作用^[123]。TiO₂中C峰归因于TiO₂合成过程中钛酸四丁酯水解后残留的有机碳，ChCl/H-TiO₂中多了来自于DES的碳，碳含量不光比TiO₂多，比ChCl/E-TiO₂也要明显增多，但还是没有形成新的结合能峰，与已有碳存在方式相同，没有掺杂入TiO₂的晶格中。从（c）中可以很明显的看出两种催化剂均具有典型的TiO₂双峰结构，分别对应TiO₂的Ti⁴⁺ 2p_3/2和Ti⁴⁺ 2p_1/2。（d）中两种催化剂结合能最低的在530.32 eV和530.51 eV的峰是典型的Ti-O-Ti晶格氧，其次是表面Ti-OH。同时在ChCl/H-TiO₂的O 1s谱图中左端多出来了一个峰，结合能是534.1 eV，表明催化剂中出现氧空位^[134]。ChCl/H-TiO₂的Ti 2p和O 1s轨道的结合能明显向高能量移动，这与ChCl/E-TiO₂表现出的影响类似，可以归结为催化剂纳米颗粒中Ti⁴⁺与氧空位之间较强的相互作用导致晶格结构发生畸变。
The surface elemental composition and valence state of the catalyst were analyzed using the XPS profile depicted in Figure 3. Figure 3 (a), (b), (c) and ( d) TiO2 and ChCl/H-TiO2, respectivelyThe total spectrum of the catalyst and the sub-spectra of C1s, Ti2p and O1s. (a) shows that the catalyst contains characteristic peaks of Ti, O, and C. From (b), it can be seen that both catalysts have three carbon peaks, and the binding of 284.8 eV can be used to correct the XPS profileAccording to the binding energy from small to large (the same below), it can be attributed to the role of C-C, C-O, and C=O ^[123].。 The C peak in TiO2 is attributed to TiO2The residual organic carbon after the hydrolysis of tetrabutyl titanate in the synthesis process, ChCl/H-TiO2 contains more carbon from DES, and the carbon content is not only higher than that of TiO₂, which is significantly higher than ChCl/E-TiO2, but still does not form a new binding energy peak, which is the same as the existing carbon and is not adulteratedTiO2 in the lattice.It is evident from (c) that both catalysts have a typical TiO2 doublet structure, corresponding to Ti4⁺2p of TiO2_{, respectively3/2} and Ti^{4 +} 2p_1/2. (d) The lowest binding energy of the two catalysts is 530The peaks of 32 eV and 530.51 eV are typical of Ti-O-Ti lattice oxygen, followed by surfaceTi-OH。 At the same time, there is an extra peak at the left end of the O 1s spectrum of ChCl/H-TiO2, and the binding energy is 534.1 eV. indicates the presence of oxygen vacancies in the catalyst ^[134]. The binding energy of the Ti 2p and O1s orbitals of ChCl/H-TiO2 shifted significantly to high energy, which is similar to the effect exhibited by ChCl/E-TiO2, can be attributed to Ti in catalyst nanoparticles The strong interaction between ⁴⁺ and oxygen vacancies leads to the distortion of the lattice structure.

图3 TiO₂和ChCl/H-TiO₂的XPS图谱，（a）总谱；（b）C 1s分谱图；（c）Ti 2p分谱图；（d）O 1s分谱图
Figure 3 TiO2 and ChCl/H-TiO2XPS Spectrum, (a) General Spectrum; (b) C 1s spectral diagram; (c) Ti 2p spectra; (d) O1s spectral diagram

3.1.4 FT-IR分析
3.1.4 FT-IR analysis

图4为TiO₂和ChCl/H-TiO₂的FT-IR谱图，其中，516 cm^-1左右的吸收峰归因于Ti−O键、1621 cm^-1左右的吸收峰由吸附水的弯曲振动引起^[135]、2353 cm^-1左右的吸收峰归因于吸附的CO₂、3473 cm^-1左右的吸收峰是表面态羟基（-OH）的伸缩振动带。两种催化剂的出峰位置相似，表明TiO₂被成功合成。与纯TiO₂相比，添加了ChCl/H的催化剂无新的吸收峰产生，这表明没有形成其他元素掺杂。这也验证了XPS的结果。
Figure 4 shows TiO2 and ChCl/H-TiO2The FT-IR spectrum, where the absorption peak is around 516 ^cm-1 The absorption peak attributed to the Ti−O bond is around 1621 ^cm-1Caused by bending vibrations of adsorbed water ^[135], 2353 ^cm-1The absorption peaks on the left and right are attributed to the adsorbed _CO2, 3473 cm^-1The left and right absorption peaks are the stretching vibration bands of the hydroxyl group (-OH) in the surface state. The peak locations of the two catalysts were similar, indicating that TiO2 was successfully synthesized. In contrast to pure TiO2, no new absorption peaks were generated in the catalyst with ChCl/H, indicating that no other elements were formedAdulterate. This also validates the results of XPS.

图4 TiO₂和ChCl/H-TiO₂的FT-IR图谱
Figure 4 TiO2 and ChCl/H-TiO2FT-IR map

3.1.5 EDS分析
3.1.5 EDS analysis

为了进一步确认催化剂的元素组成，对TiO₂和ChCl/H-TiO₂进行了能量色散X射线光谱（EDS）分析，如图5所示。在催化剂中检测到了钛（Ti）、氧（O）、碳（C）、氯（Cl）和金（Au）五种元素。其中，Au元素来自于为了增强导电性制样时表面喷涂的金，Ti元素全部来自于TiO₂，O元素主要TiO₂，还有一部分可能来自对苯二酚中的羟基，C元素一部分归因于TiO₂前体水解后遗留的杂质碳，另一部分归因于DES煅烧后残留的有机碳物质，Cl元素则全部归因于DES中作为HBA的氯化胆碱煅烧后，各元素具体的质量百分数如表1所示。从Cl的残留量可以看出，作为HBA的氯化胆碱大部分被去除，还有微量的残留，而作为HBD的对苯二酚煅烧后，有机碳残留量大大增加，从TiO₂的4.91%增加到ChCl/H-TiO₂的31.28%，且比ChCl/E-TiO₂的20.10%还要再多10.18%。从图6两种催化剂的高清数码照片可以看出TiO₂呈现白色，而碳含量较大的ChCl/H-TiO₂则为明显的黑色。这与X射线光电子能谱（XPS）分析结果一致。更多的碳物质有助于ChCl/H-TiO₂光催化性能的提升。
To further confirm the elemental composition of the catalyst, TiO2 and ChCl/H-TiO2 were paired Energy dispersive X-ray spectroscopy (EDS) analysis was performed, as shown in Figure 5. Titanium (Ti), oxygen (O), carbon (C), chlorine (Cl), and gold () were detected in the catalystAu) five elements. Among them, the Au element comes from the gold sprayed on the surface during the sample preparation to enhance the conductivity, and the Ti element is all derived from TiO₂. The O element is mainly TiO2, and some may come from the hydroxyl group in hydroquinone, and the C element is partly attributedThe impurity carbon left over after the hydrolysis of the TiO2 precursor was partly attributed to the organic carbon residue after DES calcination, and the Cl element was all attributedThe specific mass percentages of each element after calcination of choline chloride as HBA in DES are shown in Table 1. As can be seen from the residue of Cl, most of the choline chloride as HBA is removed, and there is a trace amount of residue, while after the calcination of hydroquinone as HBD, the organic carbon residue is greatly increased4.91% of TiO2 increased to ChCl/H-TiO231.28%, which is more than 20.10% of ChCl/E-TiO210.18%。From the high-resolution digital photographs of the two catalysts in Figure 6, it can be seen that TiO2 is white and has a large carbon contentChCl/H-TiO2 is distinctly black. This is consistent with the results of X-ray photoelectron spectroscopy (XPS) analysis. More carbon species contribute to the improvement of the photocatalytic performance of ChCl/H-TiO2.

图5 TiO₂和ChCl/H-TiO₂的EDS图谱
Figure 5 TiO2 and ChCl/H-TiO2EDS Atlas

表1 TiO₂、ChCl/H-TiO₂和ChCl/E-TiO₂中的各元素含量
Table 1 TiO2, ChCl/H-TiO2, andThe content of each element in ChCl/E-TiO2

图6 TiO₂和ChCl/H-TiO₂的高清数码照片
Figure 6 TiO2 and ChCl/H-TiO2HD digital photos

3.1.6 EPR分析
3.1.6 EPR analysis

电子自旋共振光谱（EPR）能够有效地分析金属氧化物表面的缺陷态。图7显示了TiO₂和ChCl/H-TiO₂的EPR信号。其中，TiO₂的谱线在检测范围内很平滑，没有大的信号波动，而ChCl/H-TiO₂谱线在g = 2.003处出现了一个很明显的波动信号，这个EPR信号归因于在ChCl/H-TiO₂表面或亚表面存在形成氧空位而出现的未成对电子。这表明TiO₂表面不存在缺陷，而ChCl/H-TiO₂表面存在大量氧空位缺陷。适量的氧空位有利于抑制电子-空穴对的复合，增强催化剂的光催化能力。这也验证了XPS分析结果。
Electron spin resonance spectroscopy (EPR) can effectively analyze the defect states on the surface of metal oxides. Figure 7 shows TiO2 and ChCl/H-TiO₂ EPR signals. Among them, the spectral line of TiO2 is smooth in the detection range without large signal fluctuations, while the line of ChCl/H-TiO2 isA clear fluctuation signal appears at g = 2.003, and this EPR signal is attributed to ChCl/H-TiO2Unpaired electrons are present on the surface or subsurface for the formation of oxygen vacancies. This indicates that there are no defects on the surface of TiO2, while there are a large number of oxygen vacancy defects on the surface of ChCl/H-TiO2. An appropriate amount of oxygen vacancies is conducive to inhibiting the recombination of electron-hole pairs and enhancing the photocatalytic ability of the catalyst. This also validates the XPS analysis results.

图7 TiO₂和ChCl/H-TiO₂的EPR图谱
Figure 7 TiO2 and ChCl/H-TiO2EPR mapping

3.1.7 BET分析
3.1.7 BET Analysis

高比表面积和孔体积可以增强催化剂的吸附能力和电子-空穴分离能力，也更有利于有机污染物的吸附和迁移，有助于提高光催化性能。氮气吸附-脱附等温线被用来检测催化剂，以确定其比表面积和孔径分布（图8（a）（b））。结果如表2所示。根据IUPAC分类，两个样品的吸附-脱附等温线属于典型的IV类等温线。在较高压力下（P/P₀ = 0.4~0.9），吸附-脱附等温线出现了滞后回线，表明制备的样品是介孔TiO₂。比表面积由TiO₂的13.36 m²/g增加至ChCl/H-TiO₂的24.14 m²/g，孔体积相对于纯TiO₂也略有增加。换句话说，DES的添加增强了催化剂的比表面积，较大的比表面积可以提供更多的吸附位点和反应位点，单位时间内可以吸附和分解更多的有机污染物，这有助于提高光催化性能。但是相比于ChCl/E-TiO₂所具有的52.48 m²/g的比表面积，ChCl/H-TiO₂不足其一半。总体来说ChCl/H-TiO₂的孔结构并没有ChCl/E-TiO₂好。但其在暗吸附阶段，ChCl/H-TiO₂的降解率却比ChCl/E-TiO₂要高很多，这说明ChCl/H-TiO₂对污染物的吸附力更强，污染物容易富集在其周围。
The high specific surface area and pore volume can enhance the adsorption capacity and electron-hole separation ability of the catalyst, and are also more conducive to the adsorption and migration of organic pollutants, which is helpful to improve the photocatalytic performance. Nitrogen adsorption-desorption isotherms were used to detect catalysts to determine their specific surface area and pore size distribution (Figure 8(a) ( b））。 The results are shown in Table 2. According to the IUPAC classification, the adsorption-desorption isotherms of the two samples belong to the typical class IV isotherms. At higher pressure (P/P₀ = 0.4~0.9), the adsorption-desorption isotherm showed a hysteresis loop, indicating that the prepared sample was mesoporousTiO₂。 The specific surface area increased from 13.36^m2/g of TiO2ChCl/H-TiO2 of 24.14^m2/g, pore volume relative to pureTiO2 also increased slightly. In other words, the addition of DES enhances the specific surface area of the catalyst, and a larger specific surface area can provide more adsorption sites and reaction sites, and more organic pollutants can be adsorbed and decomposed per unit time, which helps to improve the photocatalytic performance. However, compared to ChCl/E-TiO2, it has 52.48 ^m2/gChCl/H-TiO2 is less than half of its specific surface area. In general, the pore structure of ChCl/H-TiO2 is not as good as that of ChCl/E-TiO2.However, in the dark adsorption stage, the degradation rate of ChCl/H-TiO2 was higher than that of ChCl/E-TiO2It is much higher, which indicates that ChCl/H-TiO2 has stronger adsorption capacity for pollutants, and pollutants are easy to accumulate around it.

图8 TiO₂和ChCl/H-TiO₂的BET图谱
Figure 8 TiO2 and ChCl/H-TiO2BET Atlas

表2 TiO₂、ChCl/E-TiO₂和ChCl/H-TiO₂的比表面积，孔径和孔容
Table 2 TiO2, ChCl/E-TiO2, andSpecific surface area, pore size, and pore volume of ChCl/H-TiO2

3.1.8 UV-Vis DRS分析
3.1.8 UV-Vis DRS Analysis

图9 TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂的UV-Vis DRS图谱
Fig.9. TiO2, ChCl/C-TiO2, UV-Vis for ChCl/H-TiO2 and ChCl/R-TiO2 DRS Atlas

图9显示了纯TiO₂和三种二元酚DES制备的TiO₂的UV-Vis DRS。可以看出纯TiO₂只对紫外光区域有吸收。ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂三种催化剂对光的吸收都延伸到了可见光区域，光响应性大大提高，但同时三者的光吸收性能差别也比较大，具体为ChCl/H-TiO₂ > ChCl/C-TiO₂ > ChCl/R-TiO₂，其中ChCl/H-TiO₂对光的响应性最高。而且与多元醇DES制备的吸光性能最好的ChCl/E-TiO₂光催化剂相比，ChCl/H-TiO₂的光吸收性能也要更高，有效提高了对光的利用率。
Figure 9 shows the preparation of pure TiO2 and three diphenolsUV-Vis DRS for _TiO2. It can be seen that pure TiO2 only absorbs the ultraviolet region. ChCl/C-TiO2, ChCl/H-TiO2, and ChCl/ The light absorption of the three catalysts of R-TiO2 extends to the visible region, and the photoresponsiveness is greatly improved, but at the same time, the light absorption performance of the three catalysts is also quite different, specifically ChCl/H-TiO2 > ChCl/C-TiO2 > ChCl/R-TiO2, where ChCl/ H-TiO2 has the highest response to light. Moreover, compared with the ChCl/E-TiO2 photocatalyst with the best absorbance performance prepared by polyol DES, ChCl/H-TiO₂. The light absorption performance is also higher, which effectively improves the utilization rate of light.

3.1.9 PL分析
3.1.9 PL analysis

图10 TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂的PL图谱
Fig.10. TiO2, ChCl/C-TiO2, PL of ChCl/H-TiO2 and ChCl/R-TiO2Atlas

图10显示了TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂几种催化剂的荧光光谱，可以看出纯TiO₂的荧光强度最强，三种二元酚DES制备的催化剂的荧光强度相比于纯TiO₂都很弱，具体为ChCl/H-TiO₂ < ChCl/R-TiO₂ < ChCl/C-TiO₂，ChCl/H-TiO₂的荧光强度十分微弱。结合紫外漫反射分析，引入DES不仅增强了TiO₂对可见光的吸收能力，还增强了电子和空穴的分离速率，以达到增强光催化性能的效果。
Figure 10 shows TiO2, ChCl/C-TiO2, ChCl/H-TiO2, and ChCl/R-TiO2The fluorescence spectra of several catalysts showed that the fluorescence intensity of pure TiO2 was the strongest, and the fluorescence intensity of the catalysts prepared by the three diphenols DES was compared with that of pure TiO_{Both were} weak, specifically ChCl/H-TiO2 < ChCl/R-TiO2 < ChCl/C-TiO2, ChCl/H-TiO2 had very weak fluorescence intensity. Combined with ultraviolet diffuse reflectance analysis, the introduction of DES not only enhances the absorption capacity of TiO2 for visible light, but also enhances the separation rate of electrons and holes, so as to enhance the photocatalytic performance.

3.2 DES用量结构分析
3.2 Analysis of DES dosage structure

3.2.1XRD分析
3.2.1XRD analysis

图11 不同DES用量的ChCl/H-TiO₂的XRD图谱
Fig.1-1 Different DES dosages of ChCl/H-TiO2XRD profile

图11分别显示了不同DES用量的ChCl/H-TiO₂的X射线衍射光谱。可以看到，2θ = 25.3°、37.7°、47.9°、53.9°、55.1°、62.6°、68.4°和70.5°与标准卡片（JCPDS21-1272）一致，对应锐钛矿型TiO₂的(101)、(004)、(200)、(105)、(211)、(204)、(116)和(220)晶面，证明在所有用量下TiO₂均成功合成。
Figure 1-1 shows different amounts of DES ChCl/H-TiO2X-ray diffraction spectra. As you can see, 2θ = 25.3°, 37.7°, 47.9°, 53.9°, 55.1°, 62.6°, 68.4° and 70.5°Consistent with the standard card (JCPDS21-1272), corresponding to (101) of the anatase type TiO2 、(004)、(200)、(105)、(211)、 (204), (116), and (220) crystal planes, demonstrating TiO2 at all dosages were successfully synthesized.

3.2.2UV-Vis DRS分析
3.2.2UV-Vis DRS analysis

图12 不同DES用量的ChCl/H-TiO₂的UV-Vis DRS图谱
Fig.1-2 Different DES dosages of ChCl/H-TiO2UV-Vis DRS profile

利用UV-Vis DRS来检DES用量对ChCl/H-TiO₂吸光性能的影响，结果如图12所示。针对于利用DES制备的催化剂来说，随着DES用量的增大，催化剂的光响应性都随之提升。原因是DES量多，残留的有效碳多，形成的碳物质对光具有很好的响应性
The effect of DES dosage on the absorbance of ChCl/H-TiO2 was detected by using UV-Vis DRS. The results are shown in Figure 12. For the catalyst prepared by DES, the photoresponsiveness of the catalyst is improved with the increase of DES dosage. The reason is that the amount of DES is large, and the residual effective carbon is large, and the carbon material formed has a good response to light

3.3光催化性能评价
3.3 Photocatalytic performance evaluation

3.3.1 光催化性能测试
3.3.1 Photocatalytic performance test

为了评估催化剂的光催化性能，在氙灯模拟的可见光照射下对亚甲基蓝（MB）溶液（20 mg/L）的降解速率进行了评估，分别测试了纯TiO₂和添加了三种二元酚DES合成的TiO₂的光催化性能。图13（a）展示了几种催化剂降解MB溶液的性能，三种添加了DES的催化剂的催化性能差别较大，ChCl/H-TiO₂ > ChCl/C-TiO₂ > ChCl/R-TiO₂，但均高于纯TiO₂。ChCl/H-TiO₂在0~40 min阶段的降解速率较快，而40 min后趋于平缓，这是因为MB溶液的浓度随着降解逐渐降低，最终接近完全降解，光催化降解120 min时的降解率达到95.7%。
To evaluate the photocatalytic performance of the catalyst, the degradation rate of methylene blue (MB) solution (20 mg/L) was evaluated under xenon lamp-simulated visible light irradiation, and pure TiO was tested separately ₂and the photocatalytic performance of TiO2 synthesized with the addition of three diphenols. Figure 13(a) illustrates the performance of several catalysts for the degradation of MB solutions, three with the addition of DESThe catalytic performance of the catalyst varies greatly, ChCl/H-TiO₂%3E ChCl/C-TiO₂%3E ChCl/R-TiO₂, but both are higher than pure TiO2. The degradation rate of ChCl/H-TiO2 was faster at 0~40 min stage, and tended to be flat after 40 minThe concentration of MB solution gradually decreased with degradation, and finally it was close to complete degradation, and the degradation rate reached 95.7% after 120 min of photocatalytic degradation.

图13 光催化降解MB溶液性能图（a）；降解MB溶液的拟一级动力学拟合结果（b）
Fig.13. Performance diagram of photocatalytic degradation of MB solution (a); Fitting results of first-order kinetics for degraded MB solution (b).

为了进一步定量评估这些催化剂的光催化效率，我们分析了这些催化剂的拟一级动力学，如图13（b）所示。TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂和ChCl/R-TiO₂，它们的动力学常数分别为0.00259、0.01082、0.02478和0.00421 min^-1。ChCl/H-TiO₂的动力学常数最大，表明其降解MB溶液的速率最快，是纯TiO₂的9.57倍，同时是ChCl/E-TiO₂的1.60倍。结果表明，由邻苯二酚、对苯二酚和间苯二酚和氯化胆碱组成的DES显著增强了TiO₂光催化降解MB溶液的速率，即提高了催化剂的光催化性能，但同时作为二元酚，三者合成的催化剂性能差别也较大。
To further quantitatively evaluate the photocatalytic efficiency of these catalysts, we analyzed the quasi-first-order kinetics of these catalysts, as shown in Figure 13(b). TiO₂、ChCl/C-TiO₂、ChCl/H-TiO₂ and ChCl/R-TiO2, with kinetic constants of 0.00259, respectively, 0.01082, 0.02478, and 0.00421 ^min-1. ChCl/H-TiO2 had the highest kinetic constant, indicating that it had the fastest rate of degradation of MB solution and was pure TiO₂9.57 times, and 1.60 times that of ChCl/E-TiO2. The results showed that DES composed of catechol, hydroquinone, resorcinol and choline chloride significantly enhanced the photocatalytic degradation of MB by TiO2The rate of the solution improves the photocatalytic performance of the catalyst, but at the same time, as a diphenol, the performance of the catalyst synthesized by the three is also quite different.

图14不同DES用量的ChCl/H-TiO₂的光催化降解MB溶液性能图
Figure 1-4 of different DES dosages of ChCl/H-TiO2Performance diagram of photocatalytic degradation of MB solution

为了评估催化剂的光催化性能，在氙灯模拟的可见光照射下对亚甲基蓝（MB）溶液（20 mg/L）的降解速率进行了评估，分别测试四种不同DES用量的ChCl/H-TiO₂的光催化性能。随着DES用量的增加，催化剂的光催化性能均出现先增大，后减小的趋势。当DES: Ti = 1.0时，制备的催化剂1.0 ChCl/H-TiO₂具有最佳的催化效果，在120 min内的降解率为97.0%。与UV-Vis DRS的结果相结合分析，催化剂中形成的碳物质不是越多越好，虽然碳多光响应能力强，但并不一定有助于提升催化剂的光催化性能。
To evaluate the photocatalytic performance of the catalyst, the degradation rate of methylene blue (MB) solution (20 mg/L) was evaluated under xenon lamp-simulated visible light irradiation, and four different DES were tested Photocatalytic performance of the dosage of ChCl/H-TiO2. With the increase of DES dosage, the photocatalytic performance of the catalyst first increased and then decreased. When DES:Ti = 1.0, prepare a catalyst of 1.0 ChCl/H-TiO2It had the best catalytic effect, and the degradation rate was 97.0% within 120 min. Combined with the results of UV-Vis DRS, the more carbon substances formed in the catalyst is not as much as possible, and although the carbon has a strong multi-light response, it does not necessarily help to improve the photocatalytic performance of the catalyst.

3.3.3 催化剂重复使用稳定性评价
3.3. 3. Catalyst reuse stability evaluation

催化剂的稳定性是评价催化剂重要指标，为了评估催化剂的稳定性，对循环使用的ChCl/H-TiO₂进行了稳定性研究，结果如图15所示。在每次光催化降解MB反应结束后，经过离心、纯水洗涤、再离心和干燥处理，将反应后的催化剂进行重复使用。经过五个循环后，催化剂的降解率从95.7%下降到61.4%，光催化效率有所下降，但整体变化不显著，表明ChCl/H-TiO₂具有较高的光催化稳定性，但与ChCl/E-TiO₂相比，其稳定性较差。性能下降可能是由于溶液中的污染物在循环过程中掩盖了催化剂的活性位点，导致光催化反应速率降低，同时由于其具有更多的碳物质，吸附在碳物质上的污染物无法及时被TiO₂催化降解，因此稳定性比ChCl/E-TiO₂更差。
In order to evaluate the stability of the catalyst, the stability of the recycled ChCl/H-TiO2 was studied, and the results are shown in the figure15. At the end of each photocatalytic degradation of MB, the catalyst after the reaction was reused after centrifugation, pure water washing, centrifugation and drying. After five cycles, the degradation rate of the catalyst decreased from 95.7% to 61.4%, and the photocatalytic efficiency decreased, but the overall change was not significant, indicating that ChCl/H-TiO2It has high photocatalytic stability, but its stability is poor compared with ChCl/E-TiO2. The deterioration of performance may be due to the fact that the contaminants in the solution mask the active site of the catalyst during cycling, resulting in a decrease in the photocatalytic reaction rate, and because it has more carbon species, the pollutants adsorbed on the carbon species cannot be catalyzed by TiO2 in time, so the stability ratio ChCl/E-TiO2 is worse.

图15ChCl/H-TiO₂光催化降解MB溶液循环实验
Fig.15 Cycling experiment of ChCl/H-TiO2 photocatalytic degradation of MB solution

3.3.3活性物种检测
3.3.3 Detection of active species

为了探究ChCl/H-TiO₂催化剂在可见光下降解亚甲基蓝（MB）溶液时的活性物种，我们进行了自由基捕获实验。在光催化反应中，我们分别加入了三种活性基团（h⁺、•O₂⁻和•OH）的捕获剂：三乙胺（TEA）、苯醌（BQ）和异丙醇（IPA）。根据图16中的结果，观察到向光催化反应中分别加入TEA、BQ和IPA时，MB溶液的降解率下降的大小顺序为： TEA > BQ > IPA。由此得出结论，空穴（h⁺）是该体系中的主要活性物种。
In order to explore the demolysis of methylene blue (MB) by the ChCl/H-TiO2 catalyst at visible light ) solution, we performed free radical trapping experiments. In the photocatalytic reaction, we added three active groups (h⁺, •_O2⁻and •OH): triethylamine (TEA), benzoquinone (BQ) and isopropanol (IPA). ）。 Based on the results in Figure 16, the addition of TEA, BQ, and TEA, respectively, to the photocatalytic reaction was observedIn IPA, the magnitude order of the degradation rate of MB solution decreased was as follows: TEA > BQ > IPA。 It is concluded that holes (H⁺) are the main active species in this system.

图16不同自由基捕获剂条件下ChCl/H-TiO₂催化剂可将光降解MB溶液性能
Fig. 16: ChCl/H-TiO2 catalyst can photodegrade MB solution under different radical trap conditions

5.结论
5.Conclusion

本文阐明了以氯化胆碱和二元酚作为溶剂和碳源合成的EDS对红外光有吸收的黑色缺陷C/TiO₂复合光催化剂和EDS用量对降解性能的影响。在合成过程中溶剂行为改变了TiO₂的内部结构和形貌，同时煅烧后形成的碳物质与TiO₂复合，有利于提高TiO₂的光响应性能和降低光生电子-空穴复合速率，从而提升了催化剂的光催化性能。ChCl/H-TiO₂对催化剂孔道结构的改善不明显，但具有更高的碳含量，导致其对光的吸收能力和对电子-空穴复合速率的抑制能力更强。ChCl/H-TiO₂表现出了卓越的光催化性能，光催化降解120 min时的降解率达到95.7%。ChCl/H-TiO₂的动力学常数最大达到了0.00259 min^-1，是纯TiO₂的9.57倍；重复循环使用5次之后仍能保持良好的稳定性，降解率仍达到61.4%，由于具有更稳定的苯环结构，煅烧后有更多的碳物质残留，导致ChCl/H-TiO₂拥有更强的光催化性能。同时羟基的位置也对催化剂的性能有重要影响，在二元酚中对位羟基对催化剂的性能提升最好。同时，研究发现空穴（h⁺）是该体系中的主要活性物种。通过控制DES的用量直接从碳源改变了碳含量，DES的用量设置为DES：Ti（M） = 1.0时，1.0 ChCl/H-TiO₂的光催化活性最高，在120 min内的降解率为97.0%。随着DES用量的增加，催化剂的光催化性能均呈现先增大再减小的趋势。结合UV-Vis DRS分析结果看，随着DES用量的增加，光响应性也在提高，和碳含量一致，这也证明了光响应性与DES煅烧后形成的碳物质含量成正相关，但过多的碳会阻碍光催化反应的进行。
In this paper, we elucidate the black defect C/TiO2 of EDS that absorbs infrared light and is synthesized with choline chloride and diphenols as solvents and carbon sources Effect of composite photocatalyst and EDS dosage on degradation performance. During the synthesis process, the solvent behavior changed the internal structure and morphology of TiO2, and the carbon species formed after calcination were combined with TiO2. It is beneficial to improve the photoresponse performance of TiO2 and reduce the photogenerated electron-hole recombination rate, thereby improving the photocatalytic performance of the catalyst. ChCl/H-TiO2 does not significantly improve the pore structure of the catalyst, but has a higher carbon content, resulting in a stronger ability to absorb light and inhibit the electron-hole recombination rate。 ChCl/H-TiO2 exhibited excellent photocatalytic performance, with a degradation rate of 95.7% at 120 min。 The kinetic constant of ChCl/H-TiO2 reached a maximum of 0.00259 ^min-1, which was pure9.57 times that of TiO2; After repeated recycling for 5 times, it can still maintain good stability, and the degradation rate still reaches 61.4%, due to the more stable benzene ring structure, there are more carbon residues after calcination, resulting inChCl/H-TiO2 has stronger photocatalytic performance. At the same time, the position of the hydroxyl group also has an important impact on the performance of the catalyst, and the para-hydroxyl group has the best effect on the performance of the catalyst among the diphenols. At the same time, it was found that hole (H⁺) was the main active species in the system.The carbon content is changed directly from the carbon source by controlling the amount of DES, and the amount of DES is set to DES:Ti(M) = 1.0, 1.0 ChCl/H-TiO2The photocatalytic activity was the highest, and the degradation rate was 97.0% within 120 min. With the increase of DES dosage, the photocatalytic performance of the catalyst increased first and then decreased. Combined with the results of UV-Vis DRS analysis, with the increase of DES dosage, the photoresponsiveness also increases, which is consistent with the carbon content, which also proves that the photoresponsiveness is consistent with DESThere is a positive correlation between the amount of carbon species formed after calcination, but too much carbon will hinder the progress of the photocatalytic reaction.