CN115216799A - A kind of nickel-based alloy composite electrode with gradient composition structure and its preparation method and application - Google Patents

Abstract

The invention relates to a nickel-based alloy composite electrode with a gradient component structure and a preparation method and application thereof, wherein a nickel-based body is placed in a weak acid solution for pretreatment to remove surface impurities; placing a nickel base body in a nickel base alloy catalyst precursor aqueous solution, depositing a nickel base alloy catalyst under an electrochemical condition, and continuously regulating and controlling the component concentration of a catalyst precursor to form a nickel base alloy catalyst layer with a gradient component structure; then, placing the composite electrode loaded with the catalyst in ammonium solution for selective electrochemical etching; and then, calcining to finally prepare the nickel-based alloy composite electrode with the gradient component structure. Compared with the prior art, the method realizes the in-situ growth of the catalyst on the surface of the substrate, enhances the binding force between the catalyst layer and the substrate, improves the stability of the electrode, further effectively increases the specific surface area of the catalyst layer by an ammonium liquid selective electrochemical etching method, and improves the catalytic activity of the composite electrode.

Description

A kind of nickel-based alloy composite electrode with gradient composition structure and preparation method thereof application

technical field

The invention relates to the technical field of electrolytic hydrogen production, in particular to a nickel-based alloy composite electrode with a gradient component structure and a preparation method and application thereof.

Background technique

Hydrogen energy has the characteristics of high energy density and zero carbon emission, and is considered as an ideal high-efficiency green secondary energy. Through renewable energy coupling electrolysis of water hydrogen production technology, the large-scale production of green hydrogen can be realized and the decarbonization of the entire hydrogen energy industry chain can be realized. It is considered to be an important means for my country to achieve the dual-carbon strategic goal. The sustainable development of society is of great significance.

According to the type of electrolyte, water electrolysis hydrogen production technology can be divided into alkaline water electrolysis hydrogen production, proton exchange membrane water electrolysis hydrogen production, anion exchange membrane water electrolysis hydrogen production, solid oxide water electrolysis hydrogen production and so on. Among them, the alkaline water electrolysis hydrogen production technology is the most mature and has been commercialized. Renewable energy has the characteristics of volatility, which puts forward higher requirements for the performance of alkaline water electrolysis hydrogen production device. Nickel-based electrode is the core component of alkaline water electrolysis cell, which determines the kinetics of hydrogen evolution/oxygen evolution reaction in the process of water electrolysis, which in turn determines the energy efficiency and power fluctuation adaptability of the electrolytic cell, and has an important impact on the improvement of electrolytic cell performance. The improvement of electrode performance can be achieved by loading high-performance catalysts (ie, preparing composite electrodes). The loading method of the catalyst affects the microstructure of the catalytic layer and the electrochemically active area of the composite electrode. Chinese invention patent CN113265675A discloses a method for spraying high-entropy alloy powder on the surface of an electrode substrate by a spraying process. Chinese invention patent CN113862727A discloses a method of placing a nickel matrix in a catalyst precursor water solvent and supporting NiFe or NiCo alloy catalysts by electrochemical deposition. Chinese invention patent CN114318398A discloses a method for supporting NiCoP alloy catalyst on the surface of nickel substrate by electrochemical deposition. Chinese invention patent CN111663152A discloses a method of immersing a nickel matrix in an aqueous solution of a catalyst precursor with a certain concentration, and carrying the catalyst through spontaneous redox reaction. Chinese invention patent CN114293215A discloses a method of hydrothermal reaction combined with high temperature treatment to support catalyst. The nickel matrix is put into an aqueous solution of catalyst precursor for hydrothermal reaction, and then the reaction product is placed in a reducing atmosphere tube furnace for high temperature reduction treatment , to obtain a catalyst-supported electrode.

Based on the above analysis, through the method involved in the above invention patent, the microstructure of the composite electrode after the catalyst is supported cannot be controlled. During the process of forming a catalyst layer with a certain thickness, an amorphous pore microstructure will be formed along with it, and closed pores may be formed, which will reduce the The kinetic rate of the bubbles generated during the hydrogen/oxygen evolution process, thus restricting the electrode performance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a nickel-based alloy composite electrode with a gradient composition structure and its preparation method and application.

The object of the present invention can be achieved by the following technical solutions: a method for preparing a nickel-based alloy composite electrode with a gradient component structure, first, the nickel matrix is placed in a weak acid solution for ultrasonic pretreatment to remove surface impurities; then, The nickel base is placed in an aqueous solution of a nickel-based alloy catalyst precursor, a nickel-based alloy catalyst is deposited under electrochemical conditions, and a nickel-based alloy catalytic layer with a gradient composition structure is formed by continuously adjusting the concentration of the catalyst precursor components; then, The catalyst-loaded composite electrode is placed in an ammonium solution (aqueous solution of ammonium ions) for selective electrochemical etching, and part of the nickel is dissolved in the ammonium solution using the coordination and complexation reaction of nickel and ammonium ions combined with the electrochemical environment. In order to increase the specific surface area of the catalytic layer and form a large number of open pore structures, a nickel-based alloy composite electrode with a gradient composition structure is finally obtained.

Aiming at the problem that the microstructure of the composite electrode supported by the catalyst is difficult to control, the present invention proposes a novel nickel-based alloy composite electrode with a gradient component structure and a preparation method thereof, which can realize the microstructure of the composite electrode supported by the catalyst. Effective regulation, using the coordination and complexation reaction of metal nickel and ammonium ions, the metal nickel in the catalytic layer is selectively etched under electrochemical conditions, thereby increasing the specific surface area of the catalytic layer and forming a large number of open pore structures , in order to improve the kinetic rate of the bubbles generated during the hydrogen evolution/oxygen evolution process, thereby improving the electrode performance.

Preferably, the weak acid solution includes but is not limited to one or more of citric acid, oxalic acid, dilute hydrochloric acid, and dilute sulfuric acid, and the pH is 1-4.

Preferably, the catalyst precursor aqueous solution contains Ni ²⁺ and M metal ions, M is a metal element that does not undergo a coordination complex reaction with ammonium ions, and M metal ions include but are not limited to Fe ²⁺ , Mn ^{2 +} one or more of them.

Further preferably, the initial concentration of Ni ²⁺ in the catalyst precursor aqueous solution is 0.2-1 mol/L, the initial concentration of M metal ions is 0.02-0.5 mol/L, and the Ni ²⁺ concentration in the initial electrodeposition solution is greater than that of M metal ions. concentration.

Further preferably, during the electrochemical deposition process, the catalyst precursor aqueous solution with M metal ions but not Ni ²⁺ is continuously added, and the M metal ion concentration is 0.02-0.5mol/L, so that during the entire electrodeposition process Ni The relative concentration of ²⁺ and the relative concentration of M metal ions showed a continuous gradient change, the relative concentration of Ni ²⁺ gradually decreased, and the relative concentration of M metal ions gradually increased, finally forming a nickel-based alloy catalyst layer with continuously changing composition.

Preferably, the current density used in the electrochemical deposition process is 1-500 mA/cm ² and the time is 1-60 min.

Preferably, the concentration of the ammonium solution is 0.1-2mol/L, and the ammonium compounds used in preparing the ammonium solution include but are not limited to ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium carbonate, ammonium acetate, and ammonium oxalate. one or more of them.

Preferably, the current density used in the electrochemical etching is 5-100 mA/cm ² and the time is 5-60 min.

Preferably, the preparation method of the nickel-based alloy composite electrode with gradient composition structure includes the following steps:

(1) Surface impurity removal treatment of nickel substrate: place the nickel substrate in a weak acid solution for ultrasonic treatment for 15-60min to remove surface impurities, and then rinse the nickel substrate with deionized water to a pH of 7-8;

(2) Electrochemical deposition preparation of nickel-based alloy catalyst: using a two-electrode system, the treated nickel matrix is placed as a cathode in a certain concentration of catalyst precursor aqueous solution for electrochemical deposition;

(3) Selective etching of the composite electrode: The composite electrode loaded with a nickel-based alloy catalyst layer with a gradient composition structure is placed in a certain concentration of ammonium solution for selective electrochemical etching, a two-electrode system is used, and the composite electrode is used as the anode ;

(4) Calcination treatment of composite electrode: The composite electrode after the above treatment is washed with deionized water, dried, and then calcined in a protective atmosphere. The calcination temperature is 200-600 °C, and the calcination time is 0.5-4h. , and finally a nickel-based alloy composite electrode with a gradient structure was obtained.

Preferably, the nickel matrix is nickel mesh or nickel foam.

A nickel-based alloy composite electrode with a gradient composition structure is prepared by the above preparation method.

An application of a nickel-based alloy composite electrode with a gradient composition structure, the composite electrode is used for alkaline electrolysis to produce hydrogen.

The composite electrode prepared by the invention evenly covers the nickel base alloy catalyst layer with continuously changing components on the surface of the nickel base. The content gradually increases, and the catalytic layer has a high specific surface area and a large number of open pore structures, and the prepared composite electrode exhibits excellent catalytic activity and stability.

Compared with the prior art, the present invention has the following advantages:

1. The composite electrode of the present invention has high catalytic activity and good stability. Through the electrochemical deposition method, the in-situ growth of the catalyst on the surface of the substrate is realized, the bonding force between the catalytic layer and the substrate is enhanced, and the composite electrode is effectively prevented from running for a long time. The problem of the catalytic layer falling off during the process improves the stability of the electrode, and further through the selective electrochemical etching method of ammonium solution, the specific surface area of the catalytic layer is effectively increased, and the catalytic activity of the composite electrode is improved;

2. The catalyst layer of the composite electrode of the present invention has a large specific surface area, and the etching method is mild and effective. The method of the present invention can effectively control the microstructure of the composite electrode after the catalyst is loaded. The metal nickel in the catalytic layer is selectively etched under electrochemical conditions, thereby increasing the specific surface area of the catalytic layer, and forming a large number of open pore structures to improve the kinetic rate of bubbles generated during the hydrogen evolution/oxygen evolution process. Improve electrode performance;

3. Compared with the existing acid etching method, the ammonium liquid electrochemical etching method involved in the present invention is mild and effective, without the generation of dangerous products such as hydrogen, and at the same time, selective etching for nickel components can be realized;

4. The method of the present invention is simple and feasible, safe to operate, and easy to industrialize. The nickel-based alloy composite electrode prepared by the method of the present invention has excellent hydrogen evolution/oxygen evolution catalytic activity and stability in alkaline electrolysis hydrogen production.

Description of drawings

Fig. 1 is the process flow diagram of the present invention;

Fig. 2 is the topography of nickel matrix;

Fig. 3 is the surface topography diagram of the composite electrode prepared in Example 1;

Fig. 4 is the linear scanning curve diagram of the oxygen evolution reaction of the composite electrode and nickel mesh prepared in Example 1, test conditions: two-electrode system, the composite electrode or the nickel mesh is the working electrode, the platinum sheet is the counter electrode, and the 30wt% concentration KOH aqueous solution is Electrolyte solution, the scan rate is 5mV/s;

Fig. 5 is the linear scanning curve diagram of the hydrogen evolution reaction of the composite electrode and nickel mesh prepared in Example 1, test conditions: two-electrode system, the composite electrode or the nickel mesh is the working electrode, the platinum sheet is the counter electrode, and the 30wt% concentration KOH aqueous solution is the electrolyte. solution, the scan rate is 5mV/s;

Fig. 6 is a composite electrode prepared in Example ¹ and a nickel mesh as an anode at 500mA/cm under the current density of the oxygen evolution reaction chronopotentiometry curve comparison diagram, the electrolysis time is 200 hours;

Fig. 7 is the hydrogen evolution and oxygen evolution potential comparison diagram of the composite electrode and nickel mesh prepared respectively in Examples 1-5 under the current density of 500mA/cm , test conditions: ^two -electrode system, the composite electrode or nickel mesh is the working electrode, the platinum The sheet was the counter electrode, the aqueous 30 wt% KOH solution was the electrolyte solution, and the scan rate was 5 mV/s.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are implemented on the premise of the technical solutions of the present invention, and provide detailed embodiments and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

A nickel-based alloy composite electrode with a gradient component structure for an alkaline electrolytic cell and a preparation method thereof, and the specific method steps include:

(1) Surface impurity removal treatment of nickel substrate

The nickel matrix is placed in a weak acid solution for ultrasonic treatment for 15-60min to remove surface impurities, and the weak acid solution includes and is not limited to one or more of citric acid, oxalic acid, dilute hydrochloric acid, and dilute sulfuric acid, and the pH is 1 -4; then rinse the nickel substrate with deionized water to pH 7-8. The nickel matrix is nickel mesh or nickel foam.

(2) Electrochemical deposition preparation of nickel-based alloy catalysts

The treated nickel substrate is used as a cathode and placed in a certain concentration of catalyst precursor aqueous solution for electrochemical deposition. A two-electrode system was used, and the treated nickel substrate was used as the cathode. The initial catalyst precursor aqueous solution contains Ni ²⁺ and M metal ions, M is a metal element that does not have a coordination complex reaction with ammonium ions, and M metal ions include but are not limited to Fe ²⁺ , Mn ²⁺ One or more of , wherein the initial concentration of Ni ²⁺ is 0.2-1 mol/L, the initial concentration of M metal ions is 0.02-0.5 mol/L, and the concentration of Ni ²⁺ in the initial electrodeposition solution is greater than the concentration of M metal ions. The current density used for electrochemical deposition is 1-500 mA/cm ² and the time is 1-60 min. During the electrochemical deposition process, the catalyst precursor aqueous solution with M metal ions but not Ni ²⁺ was continuously added, and the M metal ion concentration was 0.02-0.5 mol/L, so that the Ni ²⁺ concentration and M during the entire electrodeposition process were The concentration of metal ions presents a continuous gradient change, the relative concentration of Ni ²⁺ gradually decreases, and the relative concentration of M metal ions gradually increases, and finally a nickel-based alloy catalyst layer with continuously changing composition is formed.

(3) Selective etching of composite electrodes

The composite electrode loaded with a nickel-based alloy catalyst layer with a gradient composition structure was placed in a certain concentration of ammonium solution (ammonium ion aqueous solution) for selective electrochemical etching. A two-electrode system was used with the composite electrode as the anode. The concentration of the ammonium solution is 0.1-2 mol/L, and the ammonium compound used in preparing the ammonium solution includes but is not limited to one or more of ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium carbonate, ammonium acetate, and ammonium oxalate. several. The current density used in the electrochemical etching is 5-100 mA/cm ² and the time is 5-60 min.

(4) Calcination of composite electrode

The composite electrode after the above treatment is washed with deionized water, dried, and then calcined in a protective atmosphere. The calcination temperature is 200-600° C., and the calcination time is 0.5-4 h, and finally a nickel-based alloy composite electrode with a gradient structure is obtained.

The following are specific examples:

Example 1

The nickel mesh was placed in an oxalic acid solution with a pH value of 2 for ultrasonic treatment for 30 min to remove surface impurities; the treated nickel mesh was placed as a cathode in a certain concentration of catalyst precursor aqueous solution for electrochemical deposition, using a two-electrode system. , the nickel mesh is used as the cathode, the initial catalyst precursor aqueous solution is 0.5mol/L nickel chloride, 0.3mol/L ferrous chloride aqueous solution, the current density used for electrochemical deposition is 300mA/cm ² , and the time is 30min. During the deposition process, 0.3mol/L ferrous chloride aqueous solution was continuously added, so that in the formed nickel-iron catalytic layer, the relative content of nickel gradually decreased, and the relative content of iron gradually increased, and finally a nickel-iron catalytic layer with continuously changing components was formed; then The composite electrode carrying the nickel-iron catalytic layer was placed in a 1 mol/L ammonium chloride aqueous solution for selective electrochemical etching, so that part of the nickel component in the catalytic layer was dissolved, and the current density used in the electrochemical etching was 50 mA/cm ² , The time is 30min; the composite electrode after the above treatment is washed with deionized water, dried, and then calcined in a nitrogen atmosphere, the calcination temperature is 400 ° C, and the calcination time is 2h, and finally a nickel-iron alloy composite with a gradient structure is obtained. electrode.

Figure 2 shows the topography of the nickel mesh matrix, and Figure 3 shows the topography of the nickel-iron alloy composite electrode prepared in Example 1. It can be seen that the surface of the nickel mesh matrix is uniformly covered with the nickel-iron alloy catalyst, and the surface of the catalytic layer is rough and has a large amount of Open hole. In terms of performance, as shown in Figure 4, the oxygen evolution overpotential of the nickel-iron alloy composite electrode prepared in Example 1 is lower than that of the traditional nickel mesh at a current density of 500 mA/cm ^; The hydrogen evolution overpotential of the nickel-iron alloy composite electrode at a current density of 500 mA/cm ² is lower than that of the traditional nickel mesh; as shown in Figure 6, the nickel-iron alloy composite electrode prepared in Example 1 is used as the anode at a current density of 500 mA/cm ² The performance of the current density The stability is significantly better than traditional nickel mesh.

Figure 7 shows the comparison of the hydrogen evolution and oxygen evolution potentials of the nickel-based alloy composite electrodes prepared in Examples 1-5 and the nickel mesh at a current density of 500 mA/cm ^2. It can be seen that the performance of the prepared nickel-based alloy composite electrodes Both are better than nickel mesh.

Example 2

In this embodiment, the initial catalyst precursor aqueous solution is 1 mol/L nickel sulfate, 0.5 mol/L ferrous sulfate aqueous solution, the current density used for electrochemical deposition is 1 mA/cm ² , and the time is 60 min. Continuously add 0.5mol/L ferrous sulfate aqueous solution; then place the composite electrode supporting nickel-iron catalytic layer in 2mol/L ammonium nitrate aqueous solution for selective electrochemical etching, and the current density used for electrochemical etching is 5mA/cm ² , the time is 60min; then calcination is carried out in nitrogen atmosphere, the calcination temperature is 200 °C, and the calcination time is 4h, and finally a nickel-iron alloy composite electrode with a gradient structure is obtained, and the rest is the same as Example 1.

Example 3

In this embodiment, the initial catalyst precursor aqueous solution is 0.2 mol/L nickel nitrate, 0.02 mol/L manganese nitrate aqueous solution, the current density used for electrochemical deposition is 500 mA/cm ² , and the time is 1 min. Continuously add 0.02mol/L manganese nitrate aqueous solution; then place the composite electrode loaded with nickel-manganese catalytic layer in 0.1mol/L ammonium nitrate aqueous solution for selective electrochemical etching, and the current density used for electrochemical etching is 100mA/cm ² , the time is 5min; then calcination is carried out in an argon atmosphere, the calcination temperature is 600 ℃, and the calcination time is 0.5h, and finally a nickel-manganese alloy composite electrode with a gradient structure is obtained, and the rest is the same as Example 1.

Example 4

In this embodiment, the initial catalyst precursor aqueous solution is 0.8 mol/L nickel nitrate, 0.3 mol/L ferrous nitrate aqueous solution, and 0.2 mol/L manganese nitrate aqueous solution, the current density used for electrochemical deposition is 200 mA/cm ² , and the time is For 60 min, during the electrochemical deposition process, 0.3 mol/L ferrous nitrate aqueous solution and 0.2 mol/L manganese nitrate aqueous solution were continuously added; Selective electrochemical etching, the current density used for electrochemical etching is 80mA/cm ² and the time is 40min; then calcination is carried out in an argon atmosphere, the calcination temperature is 500°C, and the calcination time is 4h, and finally a gradient structure is obtained. The nickel-iron-manganese ternary alloy composite electrode is the same as in Example 1.

Example 5

In this embodiment, the initial catalyst precursor aqueous solution is 0.5mol/L nickel chloride, 0.3mol/L manganese chloride aqueous solution, 0.1mol/L ferrous chloride aqueous solution, and the current density used for electrochemical deposition is 100mA/cm ² , the time is 30min. During the electrochemical deposition process, 0.3mol/L manganese chloride aqueous solution and 0.1mol/L ferrous chloride aqueous solution are continuously added; Selective electrochemical etching was carried out in an aqueous solution of ammonium chloride. The current density of the electrochemical etching was 60 mA/cm ² and the time was 50 min. Then, the calcination treatment was carried out in a helium atmosphere. Finally, a nickel-manganese-iron ternary alloy composite electrode with a gradient structure is obtained, and the rest are the same as those in Example 1.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. A preparation method of a nickel-based alloy composite electrode with a gradient component structure is characterized by comprising the following steps of firstly, placing a nickel-based body in a weak acid solution for pretreatment, and removing surface impurities; then, placing a nickel base body in a nickel base alloy catalyst precursor water solution, depositing a nickel base alloy catalyst under an electrochemical condition, and forming a nickel base alloy catalyst layer with a gradient component structure by continuously regulating and controlling the component concentration of the catalyst precursor; then, placing the composite electrode loaded with the catalyst in ammonium solution for selective electrochemical etching; and then, calcining to finally prepare the nickel-based alloy composite electrode with the gradient component structure.

2. The method for preparing a nickel-based alloy composite electrode with a gradient composition structure as claimed in claim 1, wherein the weak acid solution includes one or more of citric acid, oxalic acid, diluted hydrochloric acid, and diluted sulfuric acid, and has a pH of 1-4.

3. The method of claim 1, wherein the catalyst precursor aqueous solution contains Ni ²⁺ And M metal ions, M being a metal element which does not undergo a coordination complex reaction with the ammonium ion, the M metal ions including but not limited to Fe ²⁺ 、Mn ²⁺ One or more of them.

4. The method for preparing a nickel-based alloy composite electrode having a gradient composition structure as claimed in claim 3, wherein Ni is contained in the catalyst precursor aqueous solution ²⁺ Initial concentration of 0.2-1mol/L, initial concentration of M metal ion of 0.02-0.5mol/L, ni in initial electrodeposition solution ²⁺ The concentration is greater than the concentration of M metal ions.

5. The method for preparing a nickel-based alloy composite electrode having a gradient composition structure as claimed in claim 4, wherein the metal ions having M but not Ni are continuously added during the electrochemical deposition process ²⁺ The concentration of M metal ions in the aqueous solution of the catalyst precursor of (1) is 0.02 to 0.5mol/L, so that Ni is present in the whole electrodeposition process ²⁺ The relative concentration and the relative concentration of M metal ions present continuous gradient change, ni ²⁺ The relative concentration is gradually reduced, the relative concentration of M metal ions is gradually increased, and finally the nickel-based alloy catalyst layer with continuously changed components is formed.

6. The junction of claim 1 having a gradient compositionThe preparation method of the structured nickel-based alloy composite electrode is characterized in that the current density used in the electrochemical deposition process is 1-500mA/cm ² The time is 1-60min; the current density used for the electrochemical etching is 5-100mA/cm ² The time is 5-60min.

7. The method for preparing the nickel-based alloy composite electrode with the gradient composition structure according to claim 1, wherein the concentration of the ammonium solution is 0.1-2mol/L, and the ammonium compound used for preparing the ammonium solution includes one or more of ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium nitrate, ammonium carbonate, ammonium acetate and ammonium oxalate.

8. The method for preparing a nickel-based alloy composite electrode having a gradient composition structure according to claim 1, comprising the steps of:

(1) Surface impurity removal treatment of a nickel matrix: putting the nickel substrate into a weak acid solution for ultrasonic treatment for 15-60min to remove surface impurities, and then washing the nickel substrate with deionized water until the pH value is 7-8;

(2) Electrochemical deposition preparation of the nickel-based alloy catalyst: adopting a two-electrode system, placing the treated nickel substrate serving as a cathode in a catalyst precursor aqueous solution with a certain concentration for electrochemical deposition;

(3) Selective etching of the composite electrode: placing a composite electrode loaded with a nickel-based alloy catalyst layer with a gradient component structure in ammonium solution with certain concentration for selective electrochemical etching, and adopting a two-electrode system with the composite electrode as an anode;

(4) Calcining the composite electrode: and cleaning the composite electrode subjected to the treatment by using deionized water, drying, and then calcining in a protective atmosphere at the temperature of 200-600 ℃ for 0.5-4h to finally obtain the nickel-based alloy composite electrode with the gradient structure.

9. A nickel-based alloy composite electrode having a gradient composition structure, which is manufactured by the manufacturing method according to any one of claims 1 to 8.

10. Use of a nickel base alloy composite electrode with a gradient composition structure according to claim 9, characterized in that the composite electrode is used for alkaline electrolytic hydrogen production.

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