Large-area sulfide electrodes for catalytic water electrolysis and methods of making the same

Abstract

The application discloses a large-area sulfide electrode for catalyzing water electrolysis and a preparation method thereof, and belongs to the technical field of hydrogen energy material preparation. The preparation steps comprise the following steps: preparing a mixed solution by taking ethanol as a solvent, a sulfur source, a reducing agent and a metal salt, placing a metal substrate in a heating environment, spraying the mixed solution on the metal substrate while volatilizing, until the mixed solution is volatilized completely, and calcining the metal substrate in a vacuum environment, and obtaining the large-area sulfide electrode for catalyzing water electrolysis after natural cooling. The raw material utilization rate is high, the ratio and content of the attached metal salt and the sulfur source on the metal substrate can be accurately controlled, a compact sulfide electrode can be formed on the metal substrate after calcination in the vacuum environment, the catalytic water electrolysis oxygen evolution activity of the catalytic electrode is better than that of the sulfide electrode obtained by a traditional hydrothermal method and a gas phase deposition method, and the bonding force with the metal substrate is relatively strong, and the catalytic electrode can be stably used for a long time under standard working conditions.

Description

Technical Field

[0001] This invention relates to a large-area sulfide electrode for catalytic water electrolysis and its preparation method, belonging to the field of hydrogen energy material preparation technology. Background Technology

[0002] With rapid societal development, energy consumption is increasing daily. Compared to traditional energy sources that produce large amounts of carbon dioxide and harmful substances during use, hydrogen only produces water after use, making it clean, environmentally friendly, and pollution-free. Furthermore, hydrogen can be produced in large quantities through photovoltaic power generation coupled with water electrolysis. Therefore, vigorously developing water electrolysis hydrogen production technology is a crucial strategy for achieving carbon emission reduction.

[0003] In water electrolysis, the oxidation process at the anode involves a four-electron transfer, and its reaction rate is relatively low compared to that at the cathode, thus becoming a key factor limiting the rate of water electrolysis. In recent years, many sulfides have exhibited good catalytic activity in the electrolytic desorption of oxygen from water, but their synthesis conditions are relatively demanding. Hydrothermal methods typically require high-temperature and high-pressure conditions exceeding 150 degrees Celsius, and the treatment of waste liquid after hydrothermal processes is also a significant problem, making them unsuitable for large-scale production. Many researchers have used high-temperature vapor deposition (HCVD) to prepare sulfides, but this method requires an inert atmosphere and continuous purging of the sample by a gas-driven sulfur source, resulting in raw material waste. Furthermore, tube furnaces have limited electrode substrate area, making them unsuitable for preparing large-area electrode materials. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a large-area sulfide electrode for catalytic water electrolysis and its preparation method, which has high raw material utilization and a large electrode substrate area.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] In a first aspect, this application provides a method for preparing a large-area sulfide electrode for catalytic water electrolysis, comprising the following steps:

[0007] A mixed solution is prepared using ethanol as a solvent, comprising a sulfur source, a reducing agent, and a metal salt; wherein the metal salt is at least one of a nickel salt and an iron salt.

[0008] The metal substrate is placed in a heated environment, and the mixed solution is sprayed onto the metal substrate while evaporating until the mixed solution has completely evaporated;

[0009] The metal substrate is calcined in a vacuum environment and then naturally cooled to obtain the large-area sulfide electrode used for catalytic water electrolysis.

[0010] The method for preparing large-area sulfide electrodes for catalytic water electrolysis provided in this application has a high raw material utilization rate and can precisely control the ratio and content of metal salts and sulfur sources attached to the metal substrate. A dense sulfide electrode can be formed on the metal substrate simply by calcination in a vacuum environment.

[0011] Furthermore, the temperature of the heating environment is 50℃~100℃. Temperatures that are too high or too low are detrimental to the uniform loading of metal salts and sulfur sources onto the metal substrate. When the temperature is too high, the sprayed mixed solution evaporates rapidly before reaching the metal substrate, resulting in insufficient adhesion of the metal salts and sulfur sources to the metal substrate; when the temperature is too low, the mixed solution evaporates slowly on the metal substrate, making the material prone to agglomeration and growth.

[0012] Furthermore, in the step of spraying the mixed solution onto the metal substrate while simultaneously evaporating it, an intermittent operation is adopted, in which the mixed solution is divided into multiple spray portions, and after each spray portion is sprayed, the next spray portion is sprayed only after the previous portion has completely evaporated.

[0013] Spraying causes a rapid drop in the temperature of the metal substrate surface. If the heating temperature of the metal substrate is increased to maintain a higher temperature, the ambient temperature will also rise, causing most of the sprayed mixture to evaporate prematurely. Furthermore, continuous evaporation results in a high vapor pressure of ethanol above the metal substrate, which is detrimental to the rapid evaporation of the mixture. Intermittent operation allows the sprayed solution to completely evaporate and solidify before the next spray, ensuring high evaporation efficiency of the sprayed solution after each spray and avoiding the need for spraying at high ambient temperatures.

[0014] Furthermore, when spraying the liquid, the spraying speed of the metal substrate per square centimeter is 18.5 μL / s to 37.2 μL / s, which is beneficial for the rapid evaporation of the mixed solution on the metal substrate, reduces the flow of the mixed solution on the metal substrate, and reduces the aggregation of mixed solution droplets on the metal substrate due to surface tension.

[0015] Furthermore, the nozzle outlet is 100mm to 300mm away from the metal substrate. Too large a distance increases the evaporation time of the mixed solution from the nozzle to the metal substrate surface, while too small a distance hinders uniform spraying.

[0016] Furthermore, the step of calcining the metal substrate in a vacuum environment includes: increasing the temperature to 200℃~400℃ at a rate of 2℃ / min~10℃ / min, and calcining for 0.5h~5h.

[0017] Furthermore, in the step of calcining the metal substrate in a vacuum environment, the vacuum level of the environment in which the metal substrate is located is below 0.1 bar, which helps to reduce air during the sulfidation process, prevents sulfides from being converted into oxides, and helps to ensure electrode performance.

[0018] Furthermore, in the step of preparing a mixed solution of sulfur source, reducing agent and metal salt using ethanol as solvent, the solution is dissolved by sonication for 1 min to 10 min, and the molar ratio of metal salt: reducing agent: sulfur source: ethanol is 1:0.1~10:0.2~20:500~5000.

[0019] Furthermore, the sulfur source is sulfur powder, thiourea, or sodium thiosulfate, the reducing agent is citric acid, sodium citrate, or ascorbic acid, the nickel salt is nickel chloride hexahydrate, and the iron salt is ferric chloride hexahydrate.

[0020] Secondly, this application provides a large-area sulfide electrode for catalytic water electrolysis, which is prepared by the method for preparing a large-area sulfide electrode for catalytic water electrolysis described in the first aspect. It has good catalytic activity and strong adhesion to the metal substrate.

[0021] The beneficial effects of this invention are: the raw material utilization rate is high, the ratio and content of the metal salt and sulfur source attached to the metal substrate can be precisely controlled, and a dense sulfide electrode can be formed on the metal substrate after calcination in a vacuum environment. The catalytic activity of this catalytic electrode in catalytic water electrolysis oxygen desorption is better than that of sulfide electrodes obtained by traditional hydrothermal method and vapor deposition method, and the bonding force with the metal substrate is strong, and it can be used stably for a long time under standard working conditions.

[0022] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0023] Figure 1 This is a physical image of a large-area sulfide electrode for catalytic water electrolysis fabricated according to Example 1 of this application.

[0024] Figure 2 , Figure 3 and Figure 4 These are scanning electron microscope (SEM) images of a large-area sulfide electrode for catalytic water electrolysis prepared according to Example 1 of this application at different magnifications.

[0025] Figure 5 This is an elemental surface scan of a large-area sulfide electrode for catalytic water electrolysis prepared according to Example 1 of this application.

[0026] Figure 6 , Figure 7 and Figure 8 These are scanning electron microscope (SEM) images of a large-area sulfide electrode for catalytic water electrolysis prepared in Example 2 of this application at different magnifications.

[0027] Figure 9 This is an elemental surface scan of a large-area sulfide electrode for catalytic water electrolysis prepared according to Example 2 of this application.

[0028] Figure 10 This is a comparison diagram of the electrochemical performance of a large-area sulfide electrode and a Ni mesh electrode prepared in Examples 1 and 2 of this application for catalytic water electrolysis.

[0029] Figure 11 This is a comparison chart of the electrochemical performance of the electrodes prepared in Example 1, Control Sample 1, and Control Sample 2.

[0030] Figure 12 This is a comparison chart of the constant current test results of the large-area sulfide electrodes for catalytic water electrolysis prepared in Examples 1 and 2 of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0032] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0033] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0034] Prior to this application date, some researchers used hydrothermal methods to grow sulfide catalyst layers in situ on metal substrates. However, hydrothermal methods require high-temperature and high-pressure environments, which are not conducive to subsequent scale-up production. Meanwhile, some researchers used tube furnaces for chemical vapor deposition on metal substrates to achieve sulfidation, but the electrode area is limited by the diameter of the tube furnace, making scale-up production difficult as well. Furthermore, prior to this application date, the preparation of sulfide electrodes required low raw material utilization rates. In hydrothermal methods, most metal salts remained in the solution, resulting in significant waste. Vapor deposition methods required large amounts of sulfur source and inert gas to continuously contact the metal substrate, increasing preparation costs. Existing literature reports that sulfides have a significant effect on catalyzing the electrolytic desorption of oxygen from water, but the precise controlled synthesis of large-area sulfides is rarely reported.

[0035] To address the above problems, this application provides a method for preparing a large-area sulfide electrode for catalytic water electrolysis, comprising the following steps:

[0036] S1: A mixed solution is prepared by using ethanol as a solvent to combine a sulfur source, a reducing agent, and a metal salt. The metal salt is at least one of a nickel salt or an iron salt.

[0037] S2: Place the metal substrate in a heated environment, and spray the mixed solution onto the metal substrate while evaporating it until the mixed solution has completely evaporated.

[0038] S3: A large-area sulfide electrode for catalytic water electrolysis is obtained by calcining a metal substrate under vacuum and then naturally cooling it. Specifically, it is a catalytic electrode used at the anode of water electrolysis.

[0039] This method enables the in-situ formation of dense sulfide catalysts. The metal elements in the sulfides are in a higher valence state, which lowers the energy barrier for hydroxyl oxidation, reducing the energy required for water electrolysis. Simultaneously, sulfide ions are oxidized to higher valence sulfate groups, resisting the erosion of active sites by some anions in the alkaline solution and stabilizing the catalytic activity of the sulfides. This catalyst exhibits good catalytic activity and strong bonding with the metal substrate. This method allows for the relatively simple preparation of large-area sulfide electrode materials, improving raw material utilization and enhancing the activity and stability of oxygen evolution in water electrolysis at the anode.

[0040] The reducing agent can be citric acid, sodium citrate, or ascorbic acid. A preferred reducing agent is a small molecule containing hydroxyl groups, possessing reducing properties and slightly acidic, thus avoiding reaction with metal salts to form precipitates. It also buffers the alkaline environment formed by the dissolution of the sulfur source. More preferably, the reducing agent is citric acid.

[0041] The sulfur source can be thiourea, sulfur powder or sodium thiosulfate, preferably thiourea.

[0042] The nickel salt in the metal salt can be nickel chloride hexahydrate or nickel nitrate hexahydrate, and the iron salt can be ferric chloride hexahydrate or ferric nitrate nonahydrate. Because nitrates pose a certain explosion risk and are not as easily decomposed and volatilized as chlorides during calcination, it is preferable that the nickel salt is nickel chloride hexahydrate and the iron salt is ferric chloride hexahydrate.

[0043] The metal substrate can be nickel mesh, nickel foam, or nickel fiber felt. Preferably, the metal substrate is nickel mesh, which is inexpensive, has excellent electrical conductivity, high mechanical strength, and is resistant to strong alkali corrosion. The specifications of the metal substrate can be, for example, 2cm*2cm or 100cm*100cm.

[0044] When preparing materials in step S1, the molar ratio of the total amount of metal salt to the reducing agent can be 1:0.1~10, preferably 1:0.5~5.

[0045] The molar ratio of metal salt to thiourea can be 1:0.2-20, and preferably, the molar ratio of metal salt to thiourea can be 1:1-10.

[0046] The molar ratio of the metal salt to ethanol is 1:500 to 5000. Preferably, the molar ratio of the metal salt to ethanol is 1:500 to 2000.

[0047] The solution is prepared at a temperature of 20℃-30℃, and can be dissolved with ultrasonic assistance for 1 to 10 minutes.

[0048] For example, step S2 can be performed by placing the metal substrate on the heating platform of the ultrasonic spraying machine, transferring the mixed solution into the syringe, preheating the heating platform at a high temperature for a period of time, and then using the spraying machine to spray the liquid evenly and slowly onto the metal substrate until the solution is exhausted. Continue heating for a period of time until the solvent has completely evaporated, and then stop heating.

[0049] The heating stage has a heating temperature of 50℃~100℃ and a preheating time of 3 to 20 minutes. The vertical distance between the spray nozzle and the metal substrate is 100mm~300mm. Taking an 18cm*18cm metal substrate as an example, the syringe injection speed is 0.1ml / min - 2ml / min. The entire mixed solution can be sprayed in 1 to 5 applications (i.e., divided into 1 to 5 portions). The time required for solvent evaporation after each application is 1 to 10 minutes.

[0050] In step S3, the calcination temperature is 200℃~400℃, the temperature rise rate is 2℃ / min~10℃ / min, and the holding time is preferably 0.5 hours to 3 hours. The calcination equipment can be a vacuum oven or a tube furnace. Preferably, a vacuum oven is used directly for calcination, which can prepare sulfide electrodes with a larger area, lower cost, and simpler operation.

[0051] Example 1

[0052] Cut an 18cm x 18cm nickel mesh and place it on the heating stage of the ultrasonic spraying machine, preheating it to 80 degrees Celsius for 5 minutes. The metal salt preparation process is as follows: add 1 mmol ferric chloride hexahydrate, 1 mmol citric acid, and 2 mmol thiourea to 20 ml ethanol, and sonicate for 5 minutes to obtain a clear solution. Using the ultrasonic spraying machine, evenly spray a total of 5 mL of the solution onto the nickel mesh each time, heating for 5 minutes, and continue spraying until all the solution is sprayed.

[0053] The nickel mesh coated with metal salt and sulfur source is transferred to a vacuum oven. After evacuating for half an hour, the temperature is increased from room temperature to 300°C at a rate of 10°C per minute and held at that temperature for 1 hour. After holding, it is allowed to cool naturally. The nickel mesh is then cleaned with pure water and ethanol and allowed to dry naturally to obtain a large-area sulfide electrode for catalytic water electrolysis, denoted as the FeS electrode. Figure 1 As shown, from Figure 1 The electrode shows a uniformly loaded black catalyst layer on the nickel mesh. Observation of the electrode under a scanning electron microscope reveals... Figures 2 to 4 As shown, this demonstrates that a dense coating is loaded onto the nickel mesh. Element mapping analysis of the electrode yielded the following results: Figure 5 ( Figure 5 As shown in the first image (Ch1 indicates the original scanning electron microscope image), Fe and S elements are found to be uniformly distributed in the outer catalytic layer.

[0054] Example 2

[0055] Cut an 18cm x 18cm nickel mesh and place it on the heating stage of the ultrasonic spraying machine, preheating it to 80 degrees Celsius for 5 minutes. The metal salt preparation process is as follows: add 1 mmol nickel chloride hexahydrate, 1 mmol citric acid, and 2 mmol thiourea to 20 ml ethanol, and sonicate for 5 minutes to obtain a clear solution. Using the ultrasonic spraying machine, evenly spray a total of 5 mL of the solution onto the nickel mesh each time, heating for 5 minutes, and continue spraying until all the solution is sprayed.

[0056] A nickel mesh coated with a metal salt and a sulfur source was transferred to a vacuum oven. After evacuating for half an hour, the temperature was increased from room temperature to 300°C at a rate of 10°C per minute and held at that temperature for one hour. After holding, the mesh was allowed to cool naturally, cleaned with pure water and ethanol, and then allowed to dry naturally. This yielded a large-area sulfide electrode for catalytic water electrolysis, denoted as the NiS electrode. The electrode was observed under a scanning electron microscope. Figures 6 to 8 As shown, this demonstrates that a dense coating is loaded onto the nickel mesh. Elemental distribution image analysis of the electrodes yielded the following results: Figure 9 ( Figure 9As shown in the first image (Ch1 indicates the original scanning electron microscope image), Ni and S elements are uniformly distributed in the outer catalyst layer. It should be noted that because the substrate is a nickel mesh, the Ni signal is more pronounced at the nickel mesh location, while the Ni signal in the outer layer appears weaker in comparison.

[0057] Control Sample 1

[0058] Cut an 18cm x 18cm nickel mesh and place it on the heating stage of an ultrasonic sprayer. Preheat at 80°C for 5 minutes. Add 1 mmol of ferric chloride hexahydrate and 1 mmol of citric acid to 20 ml of ethanol and sonicate for 5 minutes to obtain a clear solution. Using the ultrasonic sprayer, evenly spray a total of 5 mL of the solution onto the nickel mesh each time, heating for 5 minutes, and continue spraying until all the solution has been sprayed.

[0059] Weigh 1g of thiourea onto a ceramic boat and place it at the top tuyer of a tube furnace. Cut a 9cm x 9cm sample from the first step into the ceramic boat and place it at the bottom tuyer of the tube furnace. Seal the tube furnace, evacuate it for half an hour, then purge with nitrogen until the pressure inside the tube returns to normal. Open the outlet and connect it to the tail gas absorption solution. Increase the temperature from room temperature to 300°C at a rate of 10°C per minute, hold at that temperature for 1 hour, and allow it to cool naturally after the holding period. Clean the nickel mesh with pure water and ethanol, and allow it to dry naturally to obtain the FeS-CVD electrode.

[0060] Control sample 2

[0061] Sulfide electrodes were prepared using a conventional hydrothermal method.

[0062] Cut a 2cm x 5cm copper mesh and place it in a 50ml PTFE inner liner. Dissolve 1 mmol ferric chloride hexahydrate, 1 mmol citric acid, and 2 mmol thiourea in 20ml ethanol and transfer the solution to the PTFE inner liner containing the nickel mesh. After sealing the hydrothermal reactor, place it in an oven and heat at 120°C for 10 hours. After the reaction is complete, allow it to cool naturally, remove the sample, clean it with water and ethanol, and then allow it to air dry to obtain the FeS-SR electrode control sample.

[0063] The activity of FeS, NiS, FeS-CVD, FeS-SR electrodes, and pure nickel mesh substrates in water electrolysis and oxygen evolution was tested. Electrochemical testing conditions: electrode area 1 cm * 1 cm, 25℃, 1 mol / L KOH. The working electrodes were FeS, NiS, FeS-CVD, FeS-SR, and pure nickel mesh substrates (only one type was used each time), the reference electrode was Hg / HgO, and the counter electrode was a platinum sheet electrode. First, cyclic voltammetry was performed on the working electrode to achieve activation, with a scan range of 0.8 V–1.7 V vs RHE and a scan rate of 0.1 V / s, stopping the test when the electrode stabilized. Then, linear sweep voltammetry was used to test the electrochemical activity of the electrode, with a scan range of 1.2 V–1.7 V vs RHE and a scan rate of 5 mV / s. The results are as follows: Figure 10 and Figure 11 As shown.

[0064] from Figure 10 It can be seen that the FeS electrode only requires an overpotential of 377mV to reach 100mAcm. -2 It is slightly better than NiS electrodes and far superior to pure nickel mesh substrates.

[0065] from Figure 11 It is evident that the electrode prepared by the method described in this application exhibits slightly better performance than that prepared by chemical vapor deposition (CVD). Furthermore, the amount of sulfur source used in this application is significantly lower than that of the traditional CVD method, further highlighting the superiority of this method. On the other hand, CVD requires a tube furnace to provide gas transport conditions, and the tube diameter limits the electrode area. Currently, the inner diameter of commonly used quartz tubes is approximately 5 cm to 15 cm, making it impossible to prepare large-area sulfide electrodes. Electrodes prepared by the hydrothermal method exhibit the worst performance, possibly because the amount of material grown in situ on the substrate is far less than the amount of raw material added, resulting in far fewer catalytic sites than the electrodes in the embodiments of this application.

[0066] The stability test results for FeS and NiS electrodes are shown in the figure. Constant current test conditions: 25℃, 1 mol / L KOH. The working electrodes were FeS and NiS electrodes (only one type was used at a time), the counter electrode was a platinum sheet, and the current was set to 100 mA. The results are as follows: Figure 12 As shown, the electrode performance remains basically stable within 25 hours.

[0067] This application employs liquid phase spraying, where the solvent evaporates on the metal substrate while leaving a coating containing polymetallic salts and a sulfur source. The metal substrate is pre-attached with a sulfur source, eliminating the need to introduce the sulfur source and inert gas during high-temperature calcination. Furthermore, it allows for strict control of the amount of sulfur source and the elemental ratio. This approach is suitable for preparing large-area electrodes, while also improving raw material utilization and reducing the cost of preparing large-area electrodes.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for the preparation of large-area sulfide electrodes for catalytic water electrolysis, characterized by, Includes the following steps: A mixed solution is prepared using ethanol as a solvent, comprising a sulfur source, a reducing agent, and a metal salt; wherein the metal salt is at least one of a nickel salt and an iron salt. The metal substrate is placed in a heated environment, and the mixed solution is sprayed onto the metal substrate while evaporating until the mixed solution has completely evaporated; The metal substrate is calcined in a vacuum environment and then naturally cooled to obtain the large-area sulfide electrode for catalytic water electrolysis. The sulfur source is sulfur powder, thiourea, or sodium thiosulfate; the reducing agent is citric acid, sodium citrate, or ascorbic acid; the nickel salt is nickel chloride hexahydrate; and the iron salt is ferric chloride hexahydrate. The temperature of the heating environment is 50℃~100℃; In the step of spraying the mixed solution onto the metal substrate while it evaporates, an intermittent operation is adopted, in which the mixed solution is divided into multiple sprays, and after each spray is sprayed, the next spray is sprayed only after that spray has evaporated completely. When spraying the liquid, the spraying speed of the metal substrate per square centimeter is 18.5 μL / s to 37.2 μL / s; the nozzle outlet distance is 100 mm to 300 mm from the metal substrate.

2. The method for preparing a large-area sulfide electrode for catalytic water electrolysis according to claim 1, characterized by, The step of calcining the metal substrate in a vacuum environment includes: increasing the temperature to 200℃~400℃ at a rate of 2℃ / min~10℃ / min, and calcining for 0.5h~5h.

3. The method for preparing a large-area sulfide electrode for catalytic water electrolysis according to claim 1, characterized in that, In the step of calcining the metal substrate in a vacuum environment, the vacuum level of the environment in which the metal substrate is located is below 0.1 bar.

4. The method for preparing a large-area sulfide electrode for catalytic water electrolysis according to claim 1, characterized in that, In the step of preparing a mixed solution of sulfur source, reducing agent and metal salt using ethanol as solvent, the solution is dissolved by sonication for 1 min to 10 min, and the molar ratio of metal salt: reducing agent: sulfur source: ethanol is 1:0.1~10:0.2~20:500~5000.

5. A large-area sulfide electrode for catalytic water electrolysis, characterized in that, It is prepared by the method for preparing a large-area sulfide electrode for catalytic water electrolysis as described in any one of claims 1 to 4.

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