石墨烯椮杂钴铁电催化剂的制备研究   Preparation of graphene cobalt ferroelectric catalysts

氢能因其来源广泛，能量密度高，燃烧产物环境友好及运输优势等而被广泛关注。随之而来，作为＂绿氢＂重要来源之一的电解水技术也获得了空前的热度。然而，受制于电解水阳极反应效率迟缓及催化材料稀缺等，开发高效并且成本低廉的催化剂有着重大的意义。本文采用微波水热法，通过调整钴盐铁盐比例（4：1，2：1，1：1，1：2 及 $1:3$$1:3$1:31: 3 ），氟化铵浓度（ 0.007 $\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.01\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.019\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.01\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.019\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$mol*L^(-1),0.01mol*L^(-1),0.019mol*L^(-1),0.038mol*L^(-1)\mathrm{mol} \cdot \mathrm{L}^{-1}, ~ 0.01 \mathrm{~mol} \cdot \mathrm{~L}^{-1}, ~ 0.019 \mathrm{~mol} \cdot \mathrm{~L}^{-1}, ~ 0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 及 $0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.057mol*L^(-1)0.057 \mathrm{~mol} \cdot \mathrm{~L}^{-1} ）及石墨烯添加量（ $5\mathrm{mg},$$5\mathrm{mg},$5mg,5 \mathrm{mg}, ~ $10\mathrm{mg},15\mathrm{mg}$$10\mathrm{mg},15\mathrm{mg}$10mg,15mg10 \mathrm{mg}, ~ 15 \mathrm{mg} 及 25 mg ）制备出不同的石墨烯复合钴铁基催化剂，并采用线性扫描伏安法 （LSV），循环伏安法（CV），计时电位法（CP），扫描电子显微镜（SEM）和 X 射线衍射（XRD）等测试方法分析各成分用量对催化剂电化学性能，形貌结构及物相组成的影响。
Hydrogen energy has attracted widespread attention because of its wide range of sources, high energy density, environmental friendliness of combustion products and transportation advantages. Subsequently, water electrolysis technology, which is one of the important sources of "green hydrogen", has also gained unprecedented popularity. However, due to the sluggish reaction efficiency of the electrolyzed water anode and the scarcity of catalytic materials, it is of great significance to develop efficient and low-cost catalysts. In this paper, the microwave hydrothermal method was used to adjust the ratio of cobalt salt to iron salt (4:1, 2:1, 1:1, 1:2 and $1:3$$1:3$1:31: 3 ), the concentration of ammonium fluoride $\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.01\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.019\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.01\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.019\mathrm{mol}\cdot {\mathrm{L}}^{-1},0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$mol*L^(-1),0.01mol*L^(-1),0.019mol*L^(-1),0.038mol*L^(-1)\mathrm{mol} \cdot \mathrm{L}^{-1}, ~ 0.01 \mathrm{~mol} \cdot \mathrm{~L}^{-1}, ~ 0.019 \mathrm{~mol} \cdot \mathrm{~L}^{-1}, ~ 0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} (0.007 and $0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.057mol*L^(-1)0.057 \mathrm{~mol} \cdot \mathrm{~L}^{-1} ) and the amount of graphene added ( $5\mathrm{mg},$$5\mathrm{mg},$5mg,5 \mathrm{mg}, ~ $10\mathrm{mg},15\mathrm{mg}$$10\mathrm{mg},15\mathrm{mg}$10mg,15mg10 \mathrm{mg}, ~ 15 \mathrm{mg} and 25 mg), and the effects of the amount of each component on the electrochemical performance, morphology structure and phase composition of the catalyst were analyzed by linear scanning voltammetry (LSV), cyclic voltammetry (CV), chronopotentiometric (CP), scanning electron microscopy (SEM) and X-ray diffraction (XRD).

关键词：电解水，析氧反应，石墨烯，钴铁基催化剂  Keywords: water electrolysis, oxygen evolution reaction, graphene, cobalt-iron-based catalysts

目前，贵金属如铂和钯制作的催化剂仍是氧还原反应最有效的催化剂，但它们的稀缺性和高价格限制了它们的广泛应用。因此，开发低成本且性能相当的非贵金属催化剂具有重要的意义，钴和铁是相对丰富的资源，与贵金属相比，它们的成本更低，这使得基于这些材料的催化剂在经济上更具吸引力；更高效的催化剂，从而降低能源转换系统的整体成本，推动清洁能源技术的商业化进程，有助于环保和资源的可持续发展。
At present, catalysts made from precious metals such as platinum and palladium are still the most efficient catalysts for oxygen reduction reactions, but their scarcity and high price limit their wide application. Therefore, it is of great significance to develop low-cost and comparable non-precious metal catalysts, cobalt and iron are relatively abundant resources, and their cost is lower compared to precious metals, which makes catalysts based on these materials more economically attractive; More efficient catalysts, thereby reducing the overall cost of energy conversion systems, promoting the commercialization of clean energy technologies, and contributing to the sustainable development of environmental protection and resources.

（一）实验大致流程图如下：  (1) The general flow chart of the experiment is as follows:

图 1 实验流程图  Figure 1 Experimental flowchart
（二）实验流程：  (2) Experimental process:
（1）首先对泡沫镍基底进行预处理，放入盐酸和无水乙醇中分别超声清洗 5 min ，最后用去离子水冲洗干净放入真空干燥箱中干燥。
(1) Firstly, the nickel foam substrate was pretreated, put into hydrochloric acid and absolute ethanol for ultrasonic cleaning for 5 min, and finally rinsed with deionized water and put into a vacuum drying oven for drying.
（2）按照预定的实验方案进行配置前驱体溶液，取定量的 $\mathrm{Co}{\left({\mathrm{NO}}_3\right)}_{2}6{\mathrm{H}}_2\mathrm{O},{\mathrm{FeCl}}_{3}6{\mathrm{H}}_2\mathrm{O}$$\mathrm{Co}{\left({\mathrm{NO}}_3\right)}_{2}6{\mathrm{H}}_2\mathrm{O},{\mathrm{FeCl}}_{3}6{\mathrm{H}}_2\mathrm{O}$Co(NO_(3))_(2)6H_(2)O,FeCl_(3)6H_(2)O\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2} 6 \mathrm{H}_{2} \mathrm{O}, ~ \mathrm{FeCl}_{3} 6 \mathrm{H}_{2} \mathrm{O} ， ${\mathrm{CH}}_4{\mathrm{N}}_2\mathrm{O},{\mathrm{NH}}_4\mathrm{F}$${\mathrm{CH}}_4{\mathrm{N}}_2\mathrm{O},{\mathrm{NH}}_4\mathrm{F}$CH_(4)N_(2)O,NH_(4)F\mathrm{CH}_{4} \mathrm{~N}_{2} \mathrm{O}, ~ \mathrm{NH}_{4} \mathrm{~F} 和石墨烯加入 40 ml 的去离子水放烧杯中 $400\mathrm{r}/\min$$400\mathrm{r}/\min$400r//min400 \mathrm{r} / \mathrm{min} 搅拌，之后和泡沫镍基底一同放入微波反应仪中 ${120}^{\circ }\mathrm{C}$${120}^{\circ }\mathrm{C}$120^(@)C120^{\circ} \mathrm{C} 保温 1 h 。
(2) Configure the precursor solution according to the predetermined experimental plan, take a certain amount $\mathrm{Co}{\left({\mathrm{NO}}_3\right)}_{2}6{\mathrm{H}}_2\mathrm{O},{\mathrm{FeCl}}_{3}6{\mathrm{H}}_2\mathrm{O}$$\mathrm{Co}{\left({\mathrm{NO}}_3\right)}_{2}6{\mathrm{H}}_2\mathrm{O},{\mathrm{FeCl}}_{3}6{\mathrm{H}}_2\mathrm{O}$Co(NO_(3))_(2)6H_(2)O,FeCl_(3)6H_(2)O\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2} 6 \mathrm{H}_{2} \mathrm{O}, ~ \mathrm{FeCl}_{3} 6 \mathrm{H}_{2} \mathrm{O} , ${\mathrm{CH}}_4{\mathrm{N}}_2\mathrm{O},{\mathrm{NH}}_4\mathrm{F}$${\mathrm{CH}}_4{\mathrm{N}}_2\mathrm{O},{\mathrm{NH}}_4\mathrm{F}$CH_(4)N_(2)O,NH_(4)F\mathrm{CH}_{4} \mathrm{~N}_{2} \mathrm{O}, ~ \mathrm{NH}_{4} \mathrm{~F} add 40 ml of deionized water with graphene to a beaker and $400\mathrm{r}/\min$$400\mathrm{r}/\min$400r//min400 \mathrm{r} / \mathrm{min} stir, and then put it into the microwave reactor with the nickel foam substrate for ${120}^{\circ }\mathrm{C}$${120}^{\circ }\mathrm{C}$120^(@)C120^{\circ} \mathrm{C} 1 h.
（3）样品保温完成后待自然降温后取出，用去离子水清洗，放入真空干燥箱中干燥。
(3) After the insulation of the sample is completed, it will be taken out after natural cooling, cleaned with deionized water, and placed in a vacuum drying oven for drying.
（4）将不同样品进行电化学性能测试对比以优化其配方，确定最终配方后进行综合性的电化学性能测试，XRD 和 SEM 表征。
(4) Electrochemical performance tests and comparisons of different samples to optimize their formulations, and comprehensive electrochemical performance testing, XRD and SEM characterization were carried out after the final formula was determined.

（一）电化学性能分析  (1) Electrochemical performance analysis
1．不同钴盐铁盐比例  1. Different ratios of cobalt salts and iron salts
（a）

图2 不同钴盐铁盐比例样品（a）．LSV 图；（b）．Tafel 斜率图；（c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 下过电位柱状图图 2 为不同钴盐铁盐比例样品（a）．LSV 图；（b）．Tafel 斜率图；（c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 下过电位柱状图。从图2可以看出，通过 LSV，Tafel 斜率和 $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 电流密度下的过电位对样品的分析，随着钴盐铁盐比例从 4：1 变化到 $1:1$$1:1$1:11: 1 ，催化剂的电化学性能呈上升趋势，又随着钴盐铁盐比从 1：1 变化到 $1:3$$1:3$1:31: 3 ，呈现下降趋势。由此可见，钴盐铁盐浓度比 $1:1$$1:1$1:11: 1 为较佳的浓度配比。
Fig.2. Samples with different ratios of cobalt salts and iron salts (a). LSV diagrams; （b）． Tafel slope plot; （c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} Figure 2 of the lower overpotential histogram shows the samples with different ratios of cobalt salts and iron salts (a). LSV diagrams; （b）． Tafel slope plot; （c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} Lower overpotential histogram. As can be seen from Figure 2, the overpotential analysis of the sample by LSV, Tafel slope and $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} current density shows an upward trend as the ratio of cobalt salts to irons to salts changes from 4:1 to $1:1$$1:1$1:11: 1 , and a downward trend as the ratio of cobalt salts to irons to salts changes from 1:1 to $1:3$$1:3$1:31: 3 . It can be seen that the concentration ratio of cobalt salt $1:1$$1:1$1:11: 1 to iron salt is the best concentration ratio.

2．不同氟化铵浓度  2. Different ammonium fluoride concentrations
（a）

（b）

（c）

图 3 不同氟化铵浓度样品（a）．LSV 图；（b）．Tafel 斜率图；（c） $.100\mathrm{mA}{\mathrm{cm}}^{-2}$$.100\mathrm{mA}{\mathrm{cm}}^{-2}$.100mAcm^(-2).100 \mathrm{~mA} \mathrm{~cm}^{-2} 下的过电位柱状图图 3 为不同氟化铵浓度样品（a）． LSV 图；（b）．Tafel 斜率图；（c）． $100\mathrm{mA}\mathrm{cm}{}^{-2}$$100\mathrm{mA}\mathrm{cm}{}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}{ }^{-2} 下过电位柱状图。从图3可以看出，通过 LSV，Tafel 斜率和 $100\mathrm{mA}\mathrm{cm}{}^{-2}$$100\mathrm{mA}\mathrm{cm}{}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}{ }^{-2} 电流密度下的过电位对样品的分析，得出的规律当氟化铵浓度从 $0.007\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.007\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.007mol*L^(-1)0.007 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 过渡到 $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 时，催化剂的电化学性能呈现上升趋势，当氟化铵浓度由 $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 过渡到 $0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.057mol*L^(-1)0.057 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 时，呈现下降趋势，以此确定此次实验最佳的氟化铵浓度为 $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} 。
Fig. 3 Samples with different ammonium fluoride concentrations (a). LSV diagrams; （b）． Tafel slope plot; The overpotential histogram under (c) $.100\mathrm{mA}{\mathrm{cm}}^{-2}$$.100\mathrm{mA}{\mathrm{cm}}^{-2}$.100mAcm^(-2).100 \mathrm{~mA} \mathrm{~cm}^{-2} is shown in Figure 3 for samples with different ammonium fluoride concentrations (a). LSV diagrams; （b）． Tafel slope plot; （c）． $100\mathrm{mA}\mathrm{cm}{}^{-2}$$100\mathrm{mA}\mathrm{cm}{}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}{ }^{-2} Lower overpotential histogram. As can be seen from Figure 3, the analysis of the sample by the overpotential at LSV, Tafel slope and $100\mathrm{mA}\mathrm{cm}{}^{-2}$$100\mathrm{mA}\mathrm{cm}{}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}{ }^{-2} current density shows that the electrochemical performance of the catalyst shows an upward trend $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} when the ammonium fluoride concentration $0.007\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.007\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.007mol*L^(-1)0.007 \mathrm{~mol} \cdot \mathrm{~L}^{-1} transitions from , and a decreasing trend $0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.057\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.057mol*L^(-1)0.057 \mathrm{~mol} \cdot \mathrm{~L}^{-1} $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} when the ammonium fluoride concentration $0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$$0.038\mathrm{mol}\cdot {\mathrm{L}}^{-1}$0.038mol*L^(-1)0.038 \mathrm{~mol} \cdot \mathrm{~L}^{-1} transitions from .

3．不同石墨烯添加量  3. Different graphene addition amounts
（a）

图4 不同石墨烯添加量样品（a）．LSV 图；（b）．Tafel 斜率图；（c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 下过电位柱状图
Fig.4 Samples of different graphene dosages (a). LSV diagrams; （b）． Tafel slope plot; （c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} Lower overpotential histogram

图4为不同石墨烯添加量样品（a）．LSV 图；（b）．Tafel 斜率图；（c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 下过电位柱状图。从图4可以看出，通过 LSV，Tafel 斜率和 $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 电流密度下的过电位对样品的分析，得出当石墨烯的添加量由 5 mg 逐渐增加至 25 mg 时，催化剂的电化学性能呈现递减的趋势。进而，对不同石墨烯添加量的样品进行 CV 和 CP 性能测试，进一步确定其电化学性能。
Fig. 4 shows samples of different graphene dosages (a). LSV diagrams; （b）． Tafel slope plot; （c）． $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} Lower overpotential histogram. As can be seen from Figure 4, the analysis of the sample by the overpotential at LSV, Tafel slope and $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} current density shows a decreasing trend when the amount of graphene added gradually increases from 5 mg to 25 mg. Furthermore, the samples with different graphene additions were tested for CV and CP properties to further determine their electrochemical properties.

图5不同石墨烯添加量样品的 CV 图（a）． 5 mg ；（b）． 10 mg ；（c）． 15 mg ；（d） .25 mg ；不同石墨烯添加量样品的（e） ${\mathrm{C}}_{\mathrm{dl}}$${\mathrm{C}}_{\mathrm{dl}}$C_(dl)\mathrm{C}_{\mathrm{dl}} 对比图和（f）ECSA 对比图
Figure 5: CV plots of samples with different graphene dosages (a). 5 mg ； （b）． 10 mg ； （c）． 15 mg ； （d） .25 mg ； Comparison of (e) ${\mathrm{C}}_{\mathrm{dl}}$${\mathrm{C}}_{\mathrm{dl}}$C_(dl)\mathrm{C}_{\mathrm{dl}} and (f) ECSA of different graphene addition samples
图5为不同石墨烯添加量样品的 CV 图， ${\mathrm{C}}_{\mathrm{dl}}$${\mathrm{C}}_{\mathrm{dl}}$C_(dl)\mathrm{C}_{\mathrm{dl}} 对比图和 ECSA 对比图。从图 5 可以看出，当石墨烯的添加量由 5 mg 逐渐增加至 25 mg 时，催化剂的双电层电容和电化学活性面积都呈现递减的趋势，石墨烯添加量为 5 mg 时其双电层电容和电化学活性面积都为最大，显示出最优的电化学性能。
Figure 5 shows the CV plots, ${\mathrm{C}}_{\mathrm{dl}}$${\mathrm{C}}_{\mathrm{dl}}$C_(dl)\mathrm{C}_{\mathrm{dl}} comparison charts and ECSA comparison charts of different graphene addition samples. As can be seen from Figure 5, when the amount of graphene is gradually increased from 5 mg to 25 mg, the electric double-layer capacitance and electrochemical active area of the catalyst show a decreasing trend, and the electric double-layer capacitance and electrochemical active area of the catalyst are the largest when the graphene addition is 5 mg, showing the best electrochemical performance.

3．计时电位法（CP）分析  3. Chronopotentiometric (CP) analysis

图6 石墨烯添加量 5 mg 样品的电流－电压稳定性图（a）。不同电流密度下 $10\sim 100\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$$10\sim 100\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$10∼100mA*cm^(-2)10 \sim 100 \mathrm{~mA} \cdot \mathrm{~cm}^{-2} ；（b）．在 $30\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$$30\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$30mA*cm^(-2)30 \mathrm{~mA} \cdot \mathrm{~cm}^{-2} 电流密度下 30 h 稳定性图
Fig.6. Current-voltage stability of a sample with 5 mg of graphene (a). at different current densities $10\sim 100\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$$10\sim 100\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$10∼100mA*cm^(-2)10 \sim 100 \mathrm{~mA} \cdot \mathrm{~cm}^{-2} ; (b). Stability plot at $30\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$$30\mathrm{mA}\cdot {\mathrm{cm}}^{-2}$30mA*cm^(-2)30 \mathrm{~mA} \cdot \mathrm{~cm}^{-2} current density for 30 h
图 6 为石墨烯添加量 5 mg 样品的电流－电压稳定性图。从图 6 可以看出， $10\mathrm{mA}{\mathrm{cm}}^{-2}$$10\mathrm{mA}{\mathrm{cm}}^{-2}$10mAcm^(-2)10 \mathrm{~mA} \mathrm{~cm}^{-2} 到 $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} 的过程，每个电流下，电极电位基本保持稳定，没有显著的上升或下降趋势，说明该样品在这些电流下有良好的稳定性。在恒定电流密度 $30\mathrm{mA}{\mathrm{cm}}^{-2}$$30\mathrm{mA}{\mathrm{cm}}^{-2}$30mAcm^(-2)30 \mathrm{~mA} \mathrm{~cm}^{-2} 的条件下，随时间的增加，样品电位基本保持稳定，基本上稳定在 1.52 V ，并且 30 h 长时间测试中十分稳定，展示出十分优异的电化学稳定性。
Figure 6 shows the current-voltage stability of a sample with 5 mg of graphene. As can be seen $10\mathrm{mA}{\mathrm{cm}}^{-2}$$10\mathrm{mA}{\mathrm{cm}}^{-2}$10mAcm^(-2)10 \mathrm{~mA} \mathrm{~cm}^{-2} $100\mathrm{mA}{\mathrm{cm}}^{-2}$$100\mathrm{mA}{\mathrm{cm}}^{-2}$100mAcm^(-2)100 \mathrm{~mA} \mathrm{~cm}^{-2} from Figure 6, the electrode potential remains stable at each current without a significant upward or downward trend, indicating that the sample has good stability at these currents. Under $30\mathrm{mA}{\mathrm{cm}}^{-2}$$30\mathrm{mA}{\mathrm{cm}}^{-2}$30mAcm^(-2)30 \mathrm{~mA} \mathrm{~cm}^{-2} the condition of constant current density, the sample potential remained basically stable at 1.52 V over time, and was very stable for a long time of 30 h, showing excellent electrochemical stability.

图7为石墨烯添加量 5 mg 最佳 11\＃样品的 SEM 和 XRD 图。从图7a 可以观察到空白泡沫镍是一种具有三维多孔网络架构的基体材料，其内部包含着错综复杂的网络结构；图 7b
Figure 7 shows the optimal 11\#样品的 SEM and XRD plots of graphene addition of 5 mg. From Figure 7a, it can be observed that blank nickel foam is a matrix material with a three-dimensional porous network architecture, which contains an intricate network structure. Figure 7b