Self-supporting electrode for alkaline water electrolysis to produce hydrogen, its preparation method and application

Abstract

This invention relates to a self-supporting electrode for alkaline water electrolysis to produce hydrogen, its preparation method, and its application. The preparation method includes: using a nickel metal salt as an electroplating solution, electrodepositing a nickel mesh as the working electrode and a platinum sheet as the counter electrode to obtain a nickel mesh material with a loaded conical nickel array deposition layer; calcining the obtained nickel mesh material to obtain a calcined composite material; and using a nickel-iron metal salt electroplating solution, electrodepositing a nickel-iron hydroxide deposition layer on the composite material using the obtained composite material as the working electrode and a platinum sheet as the counter electrode to obtain an alkaline water electrolysis self-supporting electrode with both high activity and stability. Compared with existing technologies, the electrode preparation method proposed in this invention is suitable for industrial water electrolysis. It is far superior to existing electrode preparation technologies in industrial water electrolysis in terms of ease of preparation, economy, catalytic performance, and service life, greatly improving the economic benefits of industrial water electrolysis.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology through water electrolysis, and in particular to a self-supporting electrode for alkaline water electrolysis hydrogen production, its preparation method, and its application. Background Technology

[0002] With the increasing severity of energy shortages and environmental pollution, finding a renewable and clean energy source to replace fossil fuels has gradually become a focus of attention for governments worldwide. With the rapid development of wind and photovoltaic industries in my country, renewable electricity resources are becoming increasingly abundant. Therefore, utilizing renewable electricity for water electrolysis to produce hydrogen is an inevitable requirement in line with my country's energy development trend. However, in the process of water electrolysis to produce hydrogen, the oxygen evolution reaction (OER) has a high overpotential and slow kinetics, which has always been a bottleneck limiting the energy conversion efficiency of the entire water electrolysis system. A reasonable catalytic electrode design can significantly reduce energy loss and improve the efficiency of the water electrolysis reaction.

[0003] In recent years, researchers have devoted considerable effort to finding highly efficient non-precious metal-based catalysts. Numerous OER catalysts with good catalytic activity and unique structures have been prepared through various methods, including hydrothermal methods, high-temperature solvothermal methods, wet chemical methods, and chemical co-deposition methods. However, these catalysts all have their limitations and cannot be directly applied from the laboratory to industrial conditions. Unlike laboratory water electrolysis, industrial water electrolysis has its own unique characteristics: large reaction area, high current density, and long operating time, which places higher demands on the design, production, and performance of catalysts. From a design perspective, industrial water electrolysis catalysts must withstand long-term operating conditions and continuous bubble impact, requiring high durability and mechanical strength. From a production perspective, such catalysts must be able to be mass-produced using a simple method at a low cost. From a performance perspective, they need to maintain good catalytic activity and minimal performance loss even under high current density conditions.

[0004] Currently, many water electrolysis catalysts are connected to the electrodes via polymer binders. This method not only reduces the active surface area of ​​the electrode and affects conductivity, but also causes the catalyst to detach after prolonged use, making it unsuitable for industrial water electrolysis. Furthermore, mass transfer losses become more pronounced at high current densities. Research has found that unremoved bubbles can clog active sites on the catalyst surface, hindering mass exchange between the solution and the electrode, thus reducing mass transfer efficiency. To promote bubble removal, researchers have proposed the design of nanoscale conical catalysts, with a tip radius as small as 5 nanometers. This fine structure is the key factor in its efficient bubble removal. However, this pointed structure is relatively fragile and easily fails after prolonged operation or bubble impact, losing its important structural features and weakening the catalytic effect. Calcination is a material treatment method that can improve crystallinity, reduce defects, and perfect the crystal structure. This process not only increases the mechanical strength of the catalyst and improves its conductivity, but also removes some non-metallic impurities, thus providing better resistance to corrosion and bubble impact. However, calcination inevitably leads to a decrease in the catalytic activity of the electrode surface.

[0005] In response to the challenges faced by existing electrodes under industrial water electrolysis conditions, there is an urgent need to design a new type of electrode that can maintain high catalytic activity while ensuring sufficient mechanical strength and durability. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of current self-supporting electrodes for alkaline water electrolysis hydrogen production, such as small specific surface area, low mechanical strength, and poor durability.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The first aspect of this invention provides a method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen, comprising the following steps:

[0009] A) In a two-electrode system, nickel metal salt is used as the electroplating solution, and nickel mesh is used as the working electrode and platinum sheet is used as the counter electrode for electrode deposition to obtain a nickel mesh material with a loaded conical nickel array deposition layer.

[0010] B) Calcining the nickel mesh material obtained in step A) yields the calcined composite material.

[0011] C) In the two-electrode system, a nickel-iron metal salt electroplating solution is used. The composite material obtained in step B) is used as the working electrode and a platinum sheet is used as the counter electrode for electrode deposition. A nickel-iron hydroxide deposition layer is obtained on the composite material, which is a self-supporting alkaline water electrolysis electrode with both activity and stability.

[0012] Further, in step A), the nickel mesh is a pretreated nickel mesh, the diameter of the nickel wire in the nickel mesh is 50-300 μm, and the mesh count of the nickel mesh is 50-400 mesh.

[0013] Further, in step A), the pretreatment process of the nickel mesh is as follows: the nickel mesh is first ultrasonically treated in dilute hydrochloric acid, then ultrasonically treated in anhydrous ethanol, then ultrasonically treated in deionized water, and finally naturally dried.

[0014] Further, in step A), the nickel metal salt electroplating solution contains: nickel chloride at a concentration of 0.6–1.4 mol / L, ammonium chloride at a concentration of 1.6–2.4 mol / L, and boric acid at a concentration of 0.6–1.2 mol / L.

[0015] Further, in step A), before use, the pH of the nickel metal salt electroplating solution is adjusted to 3-5 using a pH adjuster;

[0016] The regulator is selected from at least one of hydrochloric acid and ammonium hydroxide aqueous solution.

[0017] Further, in step A), the current density of the electrodeposition is 20–40 mA / cm². 2 The time is 30-40 minutes and the temperature is 50-60℃.

[0018] Further, in step B), the calcination temperature is 800–1000°C, and the time is 1–1.5 h.

[0019] Further, in step C), the concentration of nickel chloride in the electroplating solution of the nickel-iron metal salt is 0.04–0.10 mol / L, and the concentration of ferrous chloride is 0.02–0.04 mol / L;

[0020] In step C), the current density of the electrodeposition is 10–20 mA / cm². 2 The time is 20-30 minutes, and the temperature is 20-30℃;

[0021] In step C), after electrodeposition, the process further includes: washing the electrodeposited composite material with deionized water, then washing it with anhydrous ethanol, and then air-drying it.

[0022] A second aspect of the present invention provides a self-supporting electrode prepared by the method described above, the self-supporting electrode comprising:

[0023] Nickel mesh substrate material;

[0024] A cone-shaped nickel metal deposition layer composited on the nickel mesh substrate material;

[0025] A nickel-iron hydroxide deposition layer composited on the conical nickel metal deposition layer.

[0026] A third aspect of the present invention provides an application of the self-supporting electrode as described above in hydrogen production by water electrolysis.

[0027] Of particular importance, the mechanism of the present invention is as follows:

[0028] In this invention, the nickel mesh deposited in step A) forms a distinct conical array of metallic nickel. This conical structure not only increases the catalytically active surface area but also enhances the local electric field, increases the concentration of surrounding reactants, and facilitates bubble removal. This prevents the surface from being covered by bubbles under the high current conditions of industrial water electrolysis, maintaining low mass transfer loss and low overpotential, thus exhibiting superior catalytic performance. After calcination in step B), the composite material undergoes internal crystal phase rearrangement, exhibiting good mechanical strength and corrosion resistance. This ensures that it is not easily degraded under long-term working conditions of industrial water electrolysis and bubble impact, maintaining stable catalytic performance. The surface nickel-iron hydroxide deposition layer obtained in step C) exhibits excellent water electrolysis catalytic activity, compensating for the decrease in catalytic activity caused by calcination. Therefore, the self-supporting electrode provided by this invention can be used for alkaline water electrolysis to produce hydrogen, and is an electrode material that combines mechanical strength, corrosion resistance, and catalytic activity.

[0029] Compared with the prior art, the present invention has the following technical advantages:

[0030] Compared to existing electrode preparation methods, this invention employs electrodeposition technology, which is highly suitable for large-scale industrial production and is simple, easy to control, and inexpensive. Compared to existing catalyst structures, this invention uses a conical nickel metal substrate, which greatly promotes reaction kinetics and the bubble removal process. Compared to existing catalyst materials, this invention uses a non-precious metal nickel-iron-based material, which, after calcination, simultaneously maintains high catalytic performance, high conductivity, high mechanical strength, and corrosion resistance. Therefore, the electrode preparation method proposed in this invention is highly suitable for industrial water electrolysis. Whether in terms of ease of preparation, economy, catalytic performance, or service life, it far surpasses existing electrode preparation technologies for industrial water electrolysis, greatly improving the economic benefits of industrial water electrolysis. Attached Figure Description

[0031] Figure 1 This is a preprocessed NM microscope image from Embodiment 1 of the present invention;

[0032] Figure 2 The NiFeO in Example 1 of this invention x H y / [NC / NM] calcine Microscope image;

[0033] Figure 3 , 4 These are microscope images of the NC / NM in Embodiment 1 of the present invention after it has been working for a period of time;

[0034] Figure 5 , 6 [NC / NM] in Embodiment 1 of the present invention calcine Microscope images after a period of operation;

[0035] Figure 7 The current-voltage scan curve of the oxygen evolution reaction in Application Example 1 of this invention is shown. Detailed Implementation

[0036] This invention proposes a self-supporting electrode for alkaline water electrolysis to produce hydrogen, comprising:

[0037] Nickel mesh substrate material;

[0038] A cone-shaped nickel metal deposition layer composited on the nickel mesh substrate material;

[0039] Calcined nickel mesh substrate material and cone-shaped nickel metal deposition layer;

[0040] A nickel-iron hydroxide deposition layer composited on the calcined cone-shaped nickel metal deposition layer.

[0041] Specifically, including:

[0042] Nickel mesh substrate material;

[0043] Electrodeposition of a cone-shaped metallic nickel deposit on the nickel mesh substrate material

[0044] Calcined nickel mesh substrate material and cone-shaped nickel metal deposition layer;

[0045] Electrodeposition of a nickel-iron hydroxide deposit on the calcined cone-shaped nickel metal deposit layer.

[0046] In an embodiment of the present invention, the conical nickel metal is arranged in an array. The bottom diameter of the conical structure is 100-200 nm, and the top diameter is 5-20 nm; the spacing between individual units in the array structure is 200-300 nm.

[0047] This invention also provides a method for preparing the self-supporting electrode for alkaline water electrolysis to produce hydrogen as described above, comprising the following steps:

[0048] A) In a two-electrode system, nickel metal salt is used as the electroplating solution, and nickel mesh is used as the working electrode and platinum sheet is used as the counter electrode for electrode deposition to obtain a nickel mesh material loaded with a “conical nickel array deposition layer”.

[0049] B) Calcine the material obtained in step A) to obtain the calcined composite material.

[0050] C) In a two-electrode system, a nickel-iron metal salt electroplating solution is used. The composite material obtained in step B) is used as the working electrode and a platinum sheet is used as the counter electrode for electrodeposition. A nickel-iron hydroxide deposition layer is obtained on the composite material, thereby obtaining a self-supporting electrode for alkaline water electrolysis to produce hydrogen.

[0051] In some embodiments of the present invention, the nickel mesh is a pretreated nickel mesh. The pretreated nickel mesh is prepared according to the following method:

[0052] The nickel mesh was ultrasonically treated in dilute hydrochloric acid to remove surface oxides, then ultrasonically treated in anhydrous ethanol to remove hydrochloric acid and organic matter from the surface, and finally ultrasonically treated in deionized water to remove other residual impurities from the surface.

[0053] In some embodiments of the present invention, the concentration of the dilute hydrochloric acid is 0.5 to 1.2 mol / L; specifically, it can be 1 mol / L, and the ultrasonic treatment time can be 15 min.

[0054] In this invention, in a two-electrode system, nickel metal salt is used as the electroplating solution, a nickel mesh is used as the working electrode and a platinum sheet is used as the counter electrode. After applying current, while nickel metal is being electrodeposited, hydrogen evolution side reaction occurs at the cathode and bubbles are generated, resulting in a nickel mesh material with a loaded conical nickel array deposition layer.

[0055] In some embodiments of the present invention, the nickel metal salt electroplating solution includes nickel chloride, ammonium chloride, boric acid, and deionized water; in the nickel metal salt electroplating solution, the concentration of nickel chloride is 0.6–1.4 mol / L, the concentration of ammonium chloride is 1.6–2.4 mol / L, and the concentration of boric acid is 0.6–1.2 mol / L; specifically, in the nickel metal salt electroplating solution, the concentration of nickel chloride can be 1 mol / L, the concentration of ammonium chloride can be 2 mol / L, and the concentration of boric acid can be 0.8 mol / L.

[0056] In some embodiments of the present invention, before use, the nickel metal salt electroplating solution further includes: adjusting the pH of the nickel metal salt electroplating solution to 3-5 using a pH adjuster; specifically, it can be 4. The pH adjuster includes at least one of hydrochloric acid and ammonium hydroxide solution. The concentration of the pH adjuster can be 1 mol / L.

[0057] In some embodiments of the present invention, the electrodeposition is performed in a deposition tank. The current density of the electrodeposition is 20–40 mA / cm². 2 The electrodeposition time is 30–40 min, and the electroplating solution temperature is 50–60 °C; specifically, the electrodeposition current density can be 30 mA / cm².2 The electrodeposition time can be 30 minutes, and the electroplating solution temperature can be 60℃.

[0058] In some embodiments of the present invention, before calcination, the method further includes: cleaning the nickel mesh material loaded with the conical nickel array deposition layer using deionized water, and then air-drying it naturally.

[0059] In some embodiments of the present invention, the calcination process is carried out in a calcination furnace. The calcination temperature is 800–1000°C, and the time is 1–1.5 h; specifically, the calcination temperature is 800°C, and the time is 1 h.

[0060] In this invention, in a two-electrode system, nickel-iron metal salt is used as the electroplating solution, a nickel mesh is used as the working electrode and a platinum sheet is used as the counter electrode for electrodeposition, and a nickel-iron hydroxide deposition layer is obtained on the composite material, thereby obtaining a self-supporting electrode for alkaline water electrolysis to produce hydrogen.

[0061] In some embodiments of the present invention, the nickel-iron metal salt electroplating solution comprises nickel chloride, ferrous chloride, and deionized water. In the nickel-iron metal salt electroplating solution, the concentration of nickel chloride is 0.04–0.10 mol / L, and the concentration of ferrous chloride is 0.02–0.04 mol / L; specifically, in the nickel-iron metal salt electroplating solution, the concentration of nickel chloride is 0.08 mol / L, and the concentration of ferrous chloride is 0.02 mol / L.

[0062] In some embodiments of the present invention, the electrodeposition is performed in a deposition tank, and the current density of the electrodeposition is 10–20 mA / cm². 2 The electrodeposition time is 20–30 min, and the electroplating solution temperature is 20–30 °C; specifically, the electrodeposition current density is 10 mA / cm². 2 The electrodeposition time was 20 min, and the electroplating solution temperature was 25℃.

[0063] In some embodiments of the present invention, after electrodeposition, the process further includes washing and drying; specifically, this includes rinsing the electrodeposited composite material with deionized water, then rinsing with anhydrous ethanol, and then air drying. The number of rinsing cycles can be 3 to 5 times; specifically, 3 times. Each rinsing cycle lasts 10 to 30 seconds; specifically, 20 seconds. The water flow rate during rinsing should be gentle and should not damage the electrodeposited structure.

[0064] The present invention also provides an application of the self-supporting electrode described above for alkaline water electrolysis for hydrogen production in water electrolysis; specifically, the present invention also provides an application of the self-supporting electrode described above for alkaline water electrolysis for hydrogen production as a catalyst for water electrolysis for hydrogen production.

[0065] This invention uses a nickel mesh as the substrate material and forms a cone-shaped nickel array using an electrodeposition method. The cone-shaped nickel array structure greatly increases the actual surface area of ​​the electrode;

[0066] This invention uses a two-step electrodeposition method to form a self-supporting structure. The underlying support structure is a nickel array, which has good conductivity and mass transport characteristics, and the surface is loaded with NiFeO. x H y Thin-layer catalytic activity exhibits high efficiency.

[0067] This invention uses an electrodeposition process, eliminating the need for traditional etching or chemical deposition processes, simplifying operation, improving production efficiency, and making it suitable for large-scale industrial production.

[0068] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0069] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Any preparation methods, materials, structures, or compositional ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0070] Example 1

[0071] The preparation method of the catalyst for alkaline water electrolysis to produce hydrogen in this embodiment includes the following steps:

[0072] 1) Pretreatment of nickel mesh:

[0073] The nickel mesh was ultrasonically treated in 1 mol / L dilute hydrochloric acid to remove surface oxides, then ultrasonically treated in anhydrous ethanol to remove hydrochloric acid and organic matter, and finally ultrasonically treated in deionized water to remove other residual impurities. The ultrasonic treatment time was 15 min, and the pretreated nickel mesh (named NM) was obtained.

[0074] 2) Preparation of nickel mesh material for supporting cone-shaped nickel array deposition layers:

[0075] The nickel metal salt electroplating solution comprises nickel chloride, sodium chloride, boric acid, and deionized water; in the nickel metal salt electroplating solution, the concentration of nickel chloride is 1 mol / L, the concentration of ammonium chloride is 2 mol / L, and the concentration of boric acid is 0.8 mol / L. The pH value of the nickel metal salt electroplating solution is adjusted to 4 using dilute hydrochloric acid and ammonium chloride solution.

[0076] In the two-electrode system, the nickel metal salt electroplating solution prepared in the above steps is placed in the deposition tank. The pretreated nickel mesh is used as the working electrode, and the platinum sheet is used as the counter electrode. A current (current density of 30 mA / cm²) is applied. 2After deposition for 30 minutes at a bath temperature of 60°C, a nickel mesh material (named NC / NM) with a loaded conical nickel array deposition layer was obtained. The resulting composite material was removed from the deposition tank, cleaned with deionized water and anhydrous ethanol, and then air-dried.

[0077] 3) Calcination:

[0078] The material prepared in step 2) is placed in a calcination furnace (calcination temperature 800℃) and calcined for 1 hour to obtain the calcined composite material (named [NC / NM)). calcine ).

[0079] 4) Preparation of nickel-iron hydroxide deposition layer:

[0080] The nickel-iron metal salt electroplating solution includes nickel chloride, ferrous chloride, and deionized water; in the nickel-iron metal salt electroplating solution, the concentration of nickel chloride is 0.08 mol / L and the concentration of ferrous chloride is 0.02 mol / L.

[0081] In the two-electrode system, the nickel-iron metal salt electroplating solution prepared in the above steps is placed in the deposition tank. The composite material obtained in step 3) is used as the working electrode, and a platinum sheet is used as the counter electrode. A current (current density of 10 mA / cm²) is applied. 2 After deposition for 20 minutes at a bath temperature of 25°C, a nickel-iron hydroxide deposition layer, named (NiFeO), is obtained on the composite material. x H y / [NC / NM] calcine The resulting composite material was removed from the deposition tank, cleaned with deionized water and anhydrous ethanol (washed 3 times, each rinse lasting 20 seconds, with a gentle water flow to avoid damaging the electrodeposited structure), and then air-dried.

[0082] Depend on Figure 1 and Figure 2 It can be seen that, through the electrodeposition process, a cone-shaped array of metallic nickel is deposited on the surface of the nickel mesh. (And...) Figure 1 Compared to the smooth surface of a nickel mesh, the electrodeposition process roughens the surface of the nickel mesh, increasing the actual surface area of ​​the nickel mesh.

[0083] Depend on Figures 3-6 It can be seen that after a period of use, the surface of the unsintered electrode showed obvious structural detachment, while the structure of the sintered electrode remained intact. This indicates that the mechanical strength and corrosion resistance of the electrode were significantly improved through the sintering process.

[0084] Application Example 1

[0085] A standard three-electrode system was used, with mercury / mercury oxide (Hg / HgO) as the reference electrode, 2×2cm.2 The platinum sheet is used as the counter electrode, 1*1cm 2 The NiFeO electrode prepared in Example 1 x H y / [NC / NM] calcine As the working electrode, electrochemical tests were performed on a Corrtest electrochemical workstation using a 1 mol / L KOH solution as the electrolyte and the test temperature controlled at 25℃ to conduct the oxygen evolution reaction.

[0086] Set up control group 1, using NC / NM from Example 1 as the working electrode, and the rest of the operation is the same as the above steps;

[0087] Control group 2 was set up, using the [NC / NM] method from Example 1. calcine As the working electrode, the remaining operations are the same as the steps described above.

[0088] Linear scan Fu'an curve test: The scan rate was 5 mV / s, and the electrode potentials were all compensated with 90% iR and converted into electrode potentials relative to the reversible hydrogen potential (RHE). The calculation formula is shown in equation (*):

[0089] Overpotential (V) = Electrode potential + 0.059 × pH + Hg / HgO electrode potential - 1.23 (*)

[0090] In the formula (*), pH is the pH value of the electrolyte.

[0091] Figure 7 The current-voltage scan curve of the oxygen evolution reaction in Example 1 of this invention was used, and the test results show that:

[0092] The deposited cone-shaped nickel mesh NC / NM exhibits good OER performance; however, [NC / NM] generated after calcination... calcine While its mechanical strength increases, its OER performance decreases to some extent; however, NiFeO formed by electroplating nickel-iron hydroxide on its surface... x H y / [NC / NM] calcine Its OER performance has been greatly improved, surpassing the performance before calcination.

[0093] Therefore, in this invention, a conical nickel metal array is formed on the surface of a nickel mesh by electrodeposition. This conical structure not only increases the catalytic active surface area, but also enhances the local electric field, increases the concentration of surrounding reactants, and facilitates the discharge of bubbles. This makes it less likely to be covered by bubbles under the high current conditions of industrial water electrolysis, and it can still maintain a small mass transfer loss and a low overpotential, thus exhibiting superior catalytic performance.

[0094] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen, characterized in that, Includes the following steps: A) In a two-electrode system, nickel metal salt is used as the electroplating solution, and nickel mesh is used as the working electrode and platinum sheet is used as the counter electrode for electrode deposition to obtain a nickel mesh material with a loaded conical nickel array deposition layer. B) The nickel mesh material obtained in step A) is calcined to obtain a calcined composite material. The internal crystal phase rearrangement of the calcined composite material is observed. C) In the two-electrode system, a nickel-iron metal salt electroplating solution is used. The composite material obtained in step B) is used as the working electrode and a platinum sheet is used as the counter electrode for electrode deposition. A nickel-iron hydroxide deposition layer is obtained on the composite material, which is an alkaline water electrolysis self-supporting electrode with both activity and stability. In step B), the calcination temperature is 800~1000℃ and the time is 1~1.5h.

2. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 1, characterized in that, In step A), the nickel mesh is a pretreated nickel mesh with a nickel wire diameter of 50~300um and a mesh count of 50~400.

3. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 2, characterized in that, In step A), the pretreatment process of the nickel mesh is as follows: the nickel mesh is first ultrasonically treated in dilute hydrochloric acid, then ultrasonically treated in anhydrous ethanol, then ultrasonically treated in deionized water, and finally naturally dried.

4. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 1, characterized in that, In step A), the nickel metal salt electroplating solution contains: nickel chloride at a concentration of 0.6-1.4 mol / L, ammonium chloride at a concentration of 1.6-2.4 mol / L, and boric acid at a concentration of 0.6-1.2 mol / L.

5. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 1, characterized in that, In step A), before use, the pH of the nickel metal salt electroplating solution is adjusted to 3-5 using a pH adjuster. The regulator is selected from at least one of hydrochloric acid and ammonium hydroxide aqueous solution.

6. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 1, characterized in that, In step A), the current density of the electrodeposition is 20~40 mA / cm². 2 The time is 30-40 minutes and the temperature is 50-60℃.

7. The method for preparing a self-supporting electrode for alkaline water electrolysis to produce hydrogen according to claim 1, characterized in that, In step C), the concentration of nickel chloride in the electroplating solution of the nickel-iron metal salt is 0.04~0.10 mol / L, and the concentration of ferrous chloride is 0.02~0.04 mol / L. In step C), the current density of the electrodeposition is 10~20 mA / cm². 2 The time is 20-30 minutes, and the temperature is 20-30℃; In step C), after electrodeposition, the process further includes: washing the electrodeposited composite material with deionized water, then washing it with anhydrous ethanol, and then air-drying it.

8. A self-supporting electrode prepared by the method according to any one of claims 1 to 7, characterized in that, The self-supporting electrode includes: Nickel mesh substrate material; A calcined cone-shaped nickel metal deposition layer composited on the nickel mesh substrate material; A nickel-iron hydroxide deposition layer composited on the conical nickel metal deposition layer.

9. The application of the self-supporting electrode as described in claim 8 in hydrogen production by water electrolysis.

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