A multi-metal doped nickel-based coating electrode, a preparation method and application thereof

Abstract

The application provides a multi-metal doped nickel-based coating electrode and a preparation method and application thereof, and comprises the following steps: depositing molybdenum and tungsten active metal elements to the surface of nickel powder with a particle size of not more than 5 mu m to form a nickel-based composite powder, wherein the content of molybdenum is 10-30 wt%, and the content of tungsten is 5-10 wt%; adding the nickel-based composite powder, aluminum powder, nickel powder particles with a particle size of not less than 5 mu m, a binder and a dispersant into deionized water to stir to form a slurry, and then performing spray granulation and atmosphere sintering to obtain a nickel-based multi-element composite powder; and depositing the nickel-based multi-element composite powder to the surface of a nickel mesh substrate to obtain the multi-metal doped nickel-based coating electrode. The multi-metal doped nickel-based coating electrode has excellent catalytic activity, long-term stability, and anti-decay performance, and has low preparation cost and low energy consumption, and can effectively meet the urgent needs of the current alkaline water electrolysis hydrogen production field and adapt to the needs of large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy production technology, and particularly relates to a multi-metal doped nickel-based coated electrode, its preparation method and application. Background Technology

[0002] Alkaline water electrolysis for hydrogen production is one of the main technologies for hydrogen energy production. The operating efficiency, stability, and service life of the core equipment, the alkaline electrolyzer, directly determine the cost and large-scale application prospects of hydrogen energy production. Currently, plasma-sprayed nickel-based coated electrodes have become the main material for cathode electrodes in alkaline electrolyzers due to their excellent conductivity, good hydrogen evolution catalytic activity, and strong resistance to alkaline corrosion. Among them, nickel-aluminum composite coatings and nickel-aluminum binary alloy coatings are the most widely used. However, due to factors such as high current density, high-temperature alkaline environment, and irregular cycle start-up and shutdown, existing nickel-based coated electrodes have obvious defects such as high energy consumption, poor anti-attenuation performance, and insufficient adhesion, which seriously affect the operational stability of alkaline electrolyzers.

[0003] In existing technologies, nickel-based coated electrodes can effectively reduce hydrogen evolution potential and improve coating anti-degradation performance by adding active elements such as chromium, cobalt, molybdenum, and iron. However, due to the lack of reasonable composition design and precise structural control, they still suffer from defects such as high oxide impurity content, poor long-term stability, and high preparation cost, which seriously restrict the operating efficiency and service life of electrolytic cells, as detailed below: Regarding nickel oxide content, small-particle-size nickel powder is easily oxidized during the spraying process due to its high specific surface area, generating more inert nickel oxide (≥3%), which causes more active sites to be covered and ineffective, thereby reducing the catalytic activity of the electrode. At the same time, the loose structure of nickel oxide increases the porosity of the coating and reduces the bonding force, accelerating the performance degradation of the electrode during long-term operation. Regarding long-term stability, active elements (such as aluminum and iron) are easily dissolved under alkaline high-temperature conditions (30% KOH electrolyte, ≥80℃), resulting in a loose coating structure or even detachment, which shortens the electrode life. At the same time, the grains of electrodes prepared from single-particle-size powder are easily etched during sintering, which reduces the number of active sites, decreases conductivity, and exacerbates performance degradation. Furthermore, the spraying pores and uneven element distribution of existing nickel-based coatings also cause electrode degradation. Currently, the degradation rate of nickel-based coated electrodes after 1000 hours of long-term operation is ≥10%, which is difficult to meet the requirements for long-term stable operation of electrolytic cells. In terms of preparation cost, the cost of doping with highly catalytically active metals such as molybdenum and tungsten is high, and the gas atomization preparation process is also costly and energy-intensive, making it difficult to adapt to large-scale industrial production. Although the chemical coating method has a lower cost, it is difficult to accurately control the uniformity of elements, and the cost reduction effect is limited.

[0004] Therefore, there is an urgent need to provide a low-cost, high-performance, and highly stable multi-metal doped nickel-based coated electrode and its preparation method. By designing the powder composition, optimizing the preparation process, and controlling the coating structure, the technical problems such as severe degradation over long-term aging, high preparation cost, and difficulty in balancing adhesion and stability can be effectively alleviated, thereby meeting the needs of large-scale, long-cycle, and efficient operation of alkaline electrolyzers. Summary of the Invention

[0005] The main objective of this invention is to provide a multi-metal doped nickel-based coated electrode, its preparation method, and its application, aiming to solve the problems of poor long-term service stability, high nickel oxide content, and high cost of preparation of existing nickel-based coated electrodes.

[0006] To achieve the above objectives, the present invention provides a method for preparing a nickel-based coated electrode doped with a multi-metal matrix, comprising the following steps: S1. Molybdenum and tungsten active metal elements are deposited onto the surface of etched nickel powder to form a nickel-based composite powder, wherein the molybdenum content is 10-30 wt% and the tungsten content is 5-10 wt%; the unetched nickel powder has a particle size ≤5 μm; S2. Add nickel-based composite powder, aluminum powder, nickel powder particles with a particle size of not less than 5μm, binder and dispersant to deionized water and stir to form a slurry. Then, spray granulation and atmosphere sintering are performed to obtain nickel-based multi-component composite powder. S3. The nickel-based multi-component composite powder is deposited onto the surface of a nickel mesh substrate to obtain the multi-metal doped nickel-based coated electrode.

[0007] Furthermore, the preparation method of the nickel-based composite powder is as follows: Under an inert atmosphere, etched nickel powder is dispersed in deionized water to form a suspension. Then, ammonium heptamolybdate, tartaric acid, and hydrazine hydrate are added, and the mixture is heated to 70–85°C and kept at this temperature for 1–3 hours. During the reaction, the pH value is adjusted to 4–6 to form a molybdenum-nickel mixture. Ammonium paratungstate, sodium pyrophosphate, and a reducing agent are then added, and the mixture is kept at 70–85°C for 0.5–1.5 hours. During the reaction, the pH value is adjusted to 8–9. Finally, the reacted powder is washed and dried to obtain the nickel-based composite powder.

[0008] Furthermore, the mass ratio of the etched nickel powder to deionized water is 0.2–1.0:1; Based on the mass of etched nickel powder, the amount of ammonium heptamolybdate used is 30-70%, the amount of tartaric acid used is 1-5%, and the amount of hydrazine hydrate used is 2-10%. Based on the mass of etched nickel powder, the amount of ammonium paratungstate used is 10-30%, the amount of sodium pyrophosphate used is 1-5%, and the amount of reducing agent used is 2-10%.

[0009] Furthermore, the particle size of the nickel powder is 0.5–3 μm; The nickel powder is etched using a weak acid solution in an inert atmosphere at a temperature of 30–60°C for 5–20 minutes. The amount of nickel powder added is 10-50% of the total mass of the nickel powder and the weak acid solution; The composition of the weak acid solution is: 1-10 wt% citric acid, 5-20 wt% anhydrous ethanol, and the balance being deionized water.

[0010] Further, in step S2, the slurry is composed of the following raw materials in the following mass percentages: 30-50% nickel-based composite powder, 0.1-2.0% aluminum powder, 5-10% nickel powder particles, 0.5-5.0% binder, 0.1-2.0% dispersant, and the balance being deionized water; The nickel powder particles are carbonyl nickel powder with a particle size of 5-10 μm; The aluminum powder is spherical with a particle size of 1–3 μm.

[0011] Further, in step S2, the process parameters for spray granulation are: centrifuge head rotation frequency 250-350Hz, inlet air temperature 150-250℃, outlet air temperature 90-150℃, feed rate 10-30rpm, and atomization pressure 0.1-0.3MPa.

[0012] Furthermore, in step S2, the atmosphere sintering is carried out in a segmented sintering under an inert atmosphere. The segmented sintering process is as follows: heating from room temperature to 550°C at a heating rate of 5-10°C / min, holding for 0.5-1.0 h; then continuing to heat to 950-1150°C at a heating rate of 3-5°C / min, holding for 0.5-2.0 h.

[0013] Further, in step S3, the nickel-based multi-component composite powder is deposited onto the surface of the nickel mesh substrate by plasma spraying. The process parameters for plasma spraying are: spraying power 40-55kW; powder feeding rate 150-300g / min; spraying distance 150-180mm; spraying angle 30-70°; hydrogen flow rate 5-12L / min. During the plasma spraying process, 2 to 4 compressed air pipes are arranged to move with the spray gun, and the gas pressure is 0.5 to 0.8 MPa.

[0014] The multi-metal doped nickel-based coated electrode of the present invention is prepared by the above-described method for preparing multi-metal doped nickel-based coated electrodes.

[0015] The multi-metal doped nickel-based coated electrode prepared by this invention can be applied to alkaline water electrolysis for hydrogen production.

[0016] The technical effects of this invention are as follows: 1. This invention uses a nickel-based coated electrode doped with molybdenum and tungsten to form a nickel-molybdenum-tungsten ternary synergistic anti-degradation alloy system, which effectively reduces the hydrogen evolution overpotential, improves the stability of long-term operation, enhances the mechanical strength and corrosion resistance of the nickel-based coating, and effectively inhibits the formation of nickel oxide and the dissolution of molybdenum, thus delaying the degradation of electrode performance.

[0017] 2. The active elements molybdenum and tungsten doped in this invention are obtained by chemical deposition of industrial-grade molybdenum-tungsten ammonium salt. The process is simple, the raw material cost is low, and the energy consumption is low. This allows molybdenum and tungsten to achieve atomically uniform loading in the nickel-based coating, effectively avoiding element agglomeration and thus reducing the decrease in catalytic efficiency caused by uneven distribution of active sites. At the same time, by adding a two-component complexing agent to regulate the reduction activity of molybdenum and tungsten oxyanions, and by combining segmented pH adjustment to precisely control the deposition rate of tungsten and molybdenum ions, controllable co-deposition of heterogeneous ions is achieved. This effectively solves the problem of difficulty in synchronously controlling the reduction rate of heterogeneous ions and the doping ratio, and significantly improves the catalytic activity of the electrode of this invention.

[0018] 3. This invention uses small-particle-size nickel powder to carry active elements (tungsten, molybdenum) and large-particle-size nickel powder as the base material for particle size classification and compounding, so that molybdenum and tungsten are uniformly deposited on the surface of small-particle-size nickel powder, and produce a synergistic effect of low nickel oxide formation, high catalytic activity and high conductivity, which solves the problem of uneven active sites and provides high-quality spray powder for subsequent isostatic spraying.

[0019] 4. The present invention adopts segmented sintering, which can form a stable nickel-based solid solution while removing the binder, thereby improving the mechanical strength, anti-attenuation ability and adhesion of the nickel-based coating.

[0020] 5. This invention introduces a small amount of spherical aluminum powder into the nickel-based coating, which can form a trace nickel-aluminum alloy transition layer during sintering. This not only effectively improves the adhesion of the electrode coating, but also avoids problems such as the easy dissolution of aluminum in alkaline electrolytes, coating peeling, and accelerated attenuation, thus achieving a synergistic improvement in electrode adhesion and low attenuation performance. At the same time, by utilizing the exothermic properties of aluminum and coordinating and optimizing the spraying parameters, uniform deposition of the coating on the nickel mesh surface and controllable construction of a porous structure can be achieved, ensuring further improvement in the catalytic activity of the coated electrode.

[0021] 6. This invention uses molybdenum and tungsten doping as the core technology. Through powder composition design and preparation process optimization, cost control of high catalytic activity elements, coating structure regulation and performance optimization, the resulting multi-metal doped nickel-based coated electrode has excellent catalytic activity, long-term stability, and anti-attenuation performance. Moreover, it has low preparation cost and low energy consumption, which can effectively meet the urgent needs of the current alkaline water electrolysis hydrogen production field, effectively promote the high-quality development and technological upgrading of the hydrogen energy industry, and adapt to the needs of large-scale industrial production. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a process flow diagram of the nickel-based coating electrode with multi-metal doped structure of the present invention; Figure 2 This is a SEM image of the surface morphology of the nickel-based multi-component composite powder in Example 1 of the present invention; Figure 3 This is a particle size distribution diagram of the nickel-based multi-component composite powder in Example 1 of the present invention; Figure 4 This is a SEM image of the surface morphology of the nickel-based coated electrode with multi-metal doped coating in Embodiment 1 of the present invention; Figure 5 This is a SEM image of the surface morphology of the nickel-based coated electrode with multi-metal doped coating in Comparative Example 1 of the present invention. Figure 6 This is a SEM image of the surface morphology of the nickel-based multi-component composite powder in Comparative Example 4 of this invention. Figure 7 This is a cross-sectional optical image of the nickel-based coated electrode with multi-metal doped coating in Comparative Example 5 of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0026] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0027] All raw materials used in the embodiments and comparative examples of this invention are commercially available conventional materials, and all reagents are commercially available conventional analytical grade reagents. Specifically, ammonium heptamolybdate and ammonium paratungstate are industrial grade products. The nickel carbonyl powder was selected from Jiangsu Mengda New Material Technology Co., Ltd., and its model number is MDNi-A1.

[0028] like Figure 1 As shown, this invention provides a method for preparing a nickel-based coated electrode doped with a multi-metal, including powder preparation and coating preparation, with the specific steps as follows: S1. Roughening treatment: The small-particle-size nickel powder is etched by placing it in a weak acid solution under an inert atmosphere. The inert atmosphere can be argon and / or nitrogen to prevent the nickel powder from being oxidized.

[0029] In this invention, the small-particle-size nickel powder is nickel powder with a particle size of no more than 5 μm. Preferably, the particle size of the small-particle-size nickel powder is 0.5 to 3 μm. It has a large specific surface area, which can provide sufficient attachment sites for molybdenum and tungsten, prevent the agglomeration of tungsten and molybdenum elements, and achieve uniformity of tungsten and molybdenum, so as to improve the catalytic activity of this invention.

[0030] In this invention, the etching temperature is 30–60°C and the etching time is 5–20 min.

[0031] In this invention, the amount of small-diameter nickel powder added is 10-50% of the total mass of the small-diameter nickel powder and the weak acid solution.

[0032] In this invention, the weak acid solution is composed of: 1-10 wt% citric acid, 5-20 wt% anhydrous ethanol, and the balance being deionized water.

[0033] S2. Powder surface modification: Molybdenum and tungsten active metal elements are deposited onto the surface of small-particle-size nickel powder after etching treatment to form nickel-based composite powder, wherein the molybdenum content is 10-30 wt% and the tungsten content is 5-10 wt%.

[0034] In this invention, the deposition method for molybdenum and tungsten active metal elements is any one of electrochemical deposition, liquid-phase chemical deposition, sol-gel method, vapor phase deposition, and thermal spraying. In a specific embodiment of this invention, liquid-phase chemical deposition (i.e., chemical deposition) is used to deposit molybdenum and tungsten active metal elements onto the surface of etched small-particle nickel powder. The specific operation method is as follows: (1) Under an inert atmosphere, the etched small-particle-size nickel powder is added to deionized water for dispersion treatment to form a suspension. In this invention, the mass ratio of the etched small-particle-size nickel powder to deionized water is 0.2 to 1.0:1.

[0035] In some embodiments of the present invention, the dispersion method is stirring dispersion or ultrasonic dispersion to ensure uniform dispersion of small-diameter nickel powder. Preferably, during ultrasonic dispersion, the ultrasonic frequency is 25-50 kHz, the time is 10-30 min, and the temperature is 25-50 °C.

[0036] (2) Then add ammonium heptamolybdate ((NH4)6Mo7O 24 The reaction mixture is prepared with tartaric acid and hydrazine hydrate (N2H4·H2O), heated to 70–85°C, and maintained at this temperature for 1–3 hours. During the reaction, the pH value is adjusted to 4–6 to form a molybdenum-nickel mixture. In some embodiments of the present invention, the pH value is adjusted using dilute ammonia or dilute sulfuric acid during this reaction, and the adjustment interval is 10–20 minutes.

[0037] (3) Continue to add ammonium paratungstate ((NH4)) 10 W 12 O 41 The reaction mixture consists of 4H₂O, sodium pyrophosphate, and a reducing agent, and is kept at 70–85°C for 0.5–1.5 h, with the pH value adjusted to 8–9 during the reaction. In some embodiments of the present invention, the pH value is adjusted using dilute ammonia water, and the adjustment interval is 10–20 min.

[0038] (4) Finally, the powder after the reaction is completed is washed with deionized water 2 to 4 times and vacuum dried at 80°C for 2 hours in a vacuum drying oven to obtain small-particle-size composite nickel powder with uniformly loaded active elements (molybdenum, tungsten) on the surface, which is the nickel-based composite powder. The entire reaction process is carried out under an inert atmosphere (nitrogen and / or argon).

[0039] In this invention, during the preparation of the nickel mixture, the amount of ammonium heptamolybdate added is 30-70% of the mass of the etched small-particle nickel powder, the amount of tartaric acid added is 1-5% of the mass of the etched small-particle nickel powder, and the amount of hydrazine hydrate added is 2-10% of the mass of the etched small-particle nickel powder.

[0040] In this invention, the amount of ammonium paratungstate added is 10-30% of the mass of the etched small-particle-size nickel powder, the amount of sodium pyrophosphate added is 1-5% of the mass of the etched small-particle-size nickel powder, and the amount of reducing agent added is 2-10% of the mass of the etched small-particle-size nickel powder. The reducing agent is at least one of hydrazine hydrate, hydrazine sulfate, sodium hypophosphite, or sodium borohydride.

[0041] In this invention, molybdenum and tungsten active elements are chemically deposited on the surface of small-particle nickel powder after etching, achieving synergistic enhancement. Molybdenum can form a stable solid solution with nickel, regulating the surface electronic structure, optimizing hydrogen adsorption, reducing hydrogen evolution overpotential, and enhancing catalytic activity. Simultaneously, a dense passivation film is generated under alkaline conditions, inhibiting nickel matrix oxidation. Tungsten can form a stable solid solution with nickel, enriching at grain boundaries and strengthening the microstructure, inhibiting grain etching, reducing molybdenum dissolution in the electrolyte, and significantly improving the long-term stability of the electrode. Furthermore, using chemically deposited industrial-grade molybdenum-tungsten ammonium salt instead of mechanically mixed or mechanically alloyed metal powders can reduce the overall preparation cost by 50-65%, meeting the needs of industrial-scale promotion.

[0042] S3. Spheroidizing treatment: S31. Slurry preparation: Disperse 30-50% nickel-based composite powder, 0.1-2.0% aluminum powder, 5-10% large-diameter nickel powder particles, 0.5-5.0% binder and 0.1-2.0% dispersant in deionized water by mass percentage, make up to 100% with deionized water, stir for 1-2 hours to form a slurry.

[0043] In this invention, the large-particle-size nickel powder is carbonyl nickel powder with a particle size of not less than 5 μm. Preferably, the carbonyl nickel powder has a particle size of 5–10 μm, exhibiting low oxidation tendency and excellent flowability. This effectively inhibits nickel oxide formation, reduces powder agglomeration, and facilitates the preparation of high-sphericity precursor powders, further improving the catalytic activity, oxidation resistance, and flowability of the coating of this invention. This invention uses small-particle-size nickel powder carrying tungsten and molybdenum active elements and large-particle-size nickel powder as the base material for particle size classification and compounding. By optimizing the ratio range of small-particle-size and large-particle-size nickel powder particles, the electrode catalytic activity and low oxidation requirements can be balanced, while ensuring the flowability of the sprayed powder. This is beneficial for the stable preparation of high-quality porous coatings (i.e., the multi-metal doped nickel-based coating of this invention).

[0044] In some embodiments of the present invention, the aluminum powder is spherical with a particle size of 1–3 μm; The adhesive is one or more of polyvinyl alcohol, polyester resin, polyacrylamide, and polyvinyl butyral; The dispersant is one or more of polyethylene glycol, polyethyleneimine, and sodium hexametaphosphate.

[0045] S32. Spray granulation: The slurry formed in step S31 is spray granulated. The process parameters are: centrifuge head rotation frequency 250-350Hz, inlet air temperature 150-250℃, outlet air temperature 90-150℃, feed rate 10-30rpm, and atomization pressure 0.1-0.3 MPa. By optimizing the process parameters, porous spherical composite materials can be obtained, and the porous structure and high bonding strength of the nickel-based coating can be controlled and optimized.

[0046] S33. Atmosphere Sintering: The powder obtained by spray granulation in step S32 is placed in an inert atmosphere for segmented sintering. The specific process is as follows: the temperature is raised from room temperature to 550°C at a rate of 5–10°C / min, and held for 0.5–1.0 h; then the temperature is further raised to 950–1150°C at a rate of 3–5°C / min, and held for 0.5–2.0 h, followed by furnace cooling to room temperature to obtain porous spherical nickel-based multi-element composite powder. The inert atmosphere is argon and / or nitrogen. This invention uses inert gas protection during sintering to control the nickel oxide content below 0.5%, isolating the powder from air to prevent oxidation. Simultaneously, segmented low-temperature sintering replaces single high-temperature sintering; slow heating prevents stress cracking of the powder; medium-temperature holding removes the binder and reduces trace amounts of nickel oxide; and the high-temperature stage promotes the diffusion of tungsten and molybdenum elements into the nickel matrix, forming a stable nickel-molybdenum-tungsten solid solution.

[0047] S4. Plasma spraying: The nickel-based multi-component composite powder obtained in step S33 is deposited onto the surface of a nickel mesh substrate using plasma spraying technology to obtain the multi-metal doped nickel-based coated electrode.

[0048] In this invention, the plasma spraying process parameters are: spraying power 40–55 kW, powder feeding rate 150–300 g / min, spraying distance 150–180 mm, spraying angle 30–70°, and hydrogen flow rate 5–12 L / min; the powder feeding method is a single powder feeder with three channels. This invention achieves controllable construction of the porous structure of nickel-based coated electrodes by optimizing the plasma spraying process parameters. Specifically, it coordinates and controls the spraying power, powder feeding rate, spraying distance, hydrogen flow rate, spraying angle, cooling method, and powder feeding form to achieve precise control over the degree of powder melting and its flight state. This ensures that the particles are evenly spread and firmly bonded on the nickel mesh surface while retaining a suitable microporous structure, effectively avoiding excessive porosity or oxide content, and ensuring that the electrode has high electrochemical activity.

[0049] In some embodiments of the present invention, during the plasma spraying process, 2 to 4 compressed air pipes are arranged to move with the spray gun, and the gas pressure is 0.5 to 0.8 MPa to prevent the nickel mesh from being deformed or burned by high temperature.

[0050] In some embodiments of the present invention, the nickel mesh substrate may be a conventional nickel mesh or a nickel-containing porous substrate, specifically, but not limited to, woven nickel mesh, stretched mesh, corrugated mesh, knitted mesh, perforated mesh, or nickel foam.

[0051] In this invention, the multi-metal doped nickel-based coated electrode is prepared by the above-described method for preparing multi-metal doped nickel-based coated electrodes.

[0052] In this invention, the nickel-based coated electrode doped with multiple metals can be applied to alkaline water electrolysis for hydrogen production.

[0053] The following describes the multi-metal doped nickel-based coated electrode of the present invention, its preparation method, and its application with reference to specific embodiments.

[0054] Example 1 like Figure 1 As shown, the preparation method of the multi-metal doped nickel-based coated electrode (Ni-8wt%Mo-3.2wt%W-1wt%Al) in this embodiment is as follows: S1. Active refractory metal elements are deposited on the surface of small-particle-size nickel powder using chemical deposition.

[0055] (1) Under the protection of argon atmosphere, small-particle-size nickel powder (average particle size 2.2 μm) was dispersed in a weak acid solution with a solid content of 30 wt% for etching treatment. The weak acid solution included 5 wt% citric acid, 10 wt% anhydrous ethanol and 85 wt% deionized water, the etching temperature was 45 °C and the etching time was 10 min.

[0056] (2) Under the protection of argon atmosphere, the etched small-particle nickel powder and deionized water were mixed at a mass ratio of 0.5:1 and ultrasonically dispersed at 25℃ for 10 min with an ultrasonic frequency of 25kHz. Then, 50wt% ammonium heptamolybdate (based on the etched small-particle nickel powder, the same below), 3wt% tartaric acid (based on the etched small-particle nickel powder, the same below), and 7wt% hydrazine hydrate (based on the etched small-particle nickel powder, the same below) were added. The solution was heated to 80℃ and kept at the temperature for 2 h. During the reaction, the pH value was finely adjusted to 5 every 10 min with ammonia water (calculated as NH3, mass fraction 10%, the same below).

[0057] (3) Under the protection of argon atmosphere, after the reaction of ammonium heptamolybdate is completed, 20wt% ammonium paratungstate (based on the small particle size of etched nickel powder, the same below), 3wt% sodium pyrophosphate (based on the small particle size of etched nickel powder, the same below) and 7wt% hydrazine hydrate (based on the small particle size of etched nickel powder, the same below) are added to the solution and kept at 80℃ for 1h. During the reaction, the pH value is adjusted to 8.5 every 10 min with ammonia water (based on NH3, mass fraction 10, the same below).

[0058] (4) After the ammonium paratungstate reaction is completed, filter the powder and then wash it three times with deionized water. Place it in a vacuum drying oven and vacuum dry it at 80°C for 2 hours to obtain small-particle-size composite nickel powder (i.e., nickel-based composite powder) with uniform surface loading of active elements.

[0059] X-ray fluorescence spectroscopy (XRF) analysis revealed that the small-particle-size composite nickel powder contained 20 wt% molybdenum and 8 wt% tungsten.

[0060] S2. The small-particle-size composite nickel powder obtained in step S1 is subjected to spray granulation and atmosphere sintering to obtain nickel-based multi-component composite powder. The specific steps are as follows: Preparation of slurry: Weigh 40% small-particle-size composite nickel powder, 1.0% aluminum powder (particle size 1-3μm), 8% carbonyl nickel powder, 2.0% polyvinyl alcohol, and 1.0% polyethylene glycol by mass, and add them sequentially to 48% deionized water. Stir at 200r / min for 90min to form a slurry.

[0061] The above slurry was sprayed and granulated using a centrifugal spray granulator. The process parameters included: centrifugal head rotation frequency of 300Hz, inlet air temperature of 200℃, outlet air temperature of 120℃, feed rate of 20rpm, and atomization pressure of 0.2MPa.

[0062] The spherical powder after spray granulation was subjected to segmented atmosphere (argon) sintering. First, the temperature was slowly increased from room temperature to 550℃ at a heating rate of 8℃ / min and held for 0.5h; then, the temperature was slowly increased to 1000℃ at a heating rate of 4℃ / min and held for 1h; finally, the powder was cooled to room temperature in the furnace to obtain nickel-based multi-component composite powder that meets the requirements of plasma spray coating.

[0063] like Figure 2 The image shown is a SEM image of the surface morphology of the nickel-based multi-component composite powder after atmospheric sintering. Figure 2 It can be seen that the finished powder has a spherical and porous characteristic with good sphericity, which meets the requirements of the spray coating.

[0064] like Figure 3 The image shows the particle size distribution of nickel-based multi-component composite powder. Figure 3 It can be seen that the particle size range of the finished powder is 28.7 (D10) to 57.7 μm (D90); the powder span is calculated to be 0.7 using Span=(D90-D10) / D50, indicating that the powder particle size distribution range is narrower, which is beneficial to improving the density of the coating.

[0065] S3. A nickel-based multi-component composite powder is deposited on the surface of a nickel mesh substrate using plasma spraying technology to obtain a porous Ni-based coated electrode.

[0066] A woven nickel mesh with a mesh size of 40 mesh (wire diameter 0.19 mm) and a length of 400 mm × width was selected as the substrate and sandblasted. The sandblasting pressure was 0.5 MPa and the sandblasting angle was 50°.

[0067] The sandblasted nickel mesh was then subjected to plasma spraying. Key parameters included: spraying power of 45kW, powder feed rate of 220g / min, spraying distance of 160mm, spraying angle of 45°, hydrogen flow rate of 10L / min, and a single powder feeder with three feeders. During the spraying process, three compressed air pipes moved with the spray gun, with a gas pressure of 0.6MPa. After two cycles of spraying, a Ni-8wt%Mo-3.2wt%W-1wt%Al multi-element coating electrode (i.e., a multi-element metal-doped nickel-based coating electrode) was obtained.

[0068] like Figure 4 The image shown is a surface SEM image of a nickel-based coated electrode doped with a multi-metal matrix. From... Figure 4 It can be seen that the coating on the electrode surface is uniform and continuous, without obvious defects such as large-sized cracks or peeling, indicating that the coating deposition quality is excellent.

[0069] Testing revealed that the nickel-based coated electrode obtained in this embodiment contained 2.84 wt% nickel oxide and exhibited an ultrasonic weight loss of 1.56 mg / cm³. 2 (Test parameters: 20wt% KOH solution, ultrasonic temperature 60℃, ultrasonic duration 120min); Chamber voltage 1.711V (alkali concentration 30wt%, operating temperature 85±1℃, 4kA / m) 2 (Tested for 120 hours under current density conditions).

[0070] Example 2 like Figure 1 As shown, the preparation method of the multi-metal doped nickel-based coated electrode (Ni-3wt%Mo-1.5wt%W-0.1wt%Al) in this embodiment is as follows: S1. Roughening treatment: Active refractory metal elements are deposited on the surface of small-particle-size nickel powder using chemical deposition.

[0071] (1) Under the protection of argon atmosphere, small-diameter nickel powder (average particle size 2.2 μm) was dispersed in a weak acid solution with a solid content of 10 wt% for etching treatment. The weak acid solution included 1 wt% citric acid, 5 wt% anhydrous ethanol and 94 wt% deionized water, the etching temperature was 30℃ and the etching time was 5 min.

[0072] (2) Under the protection of argon atmosphere, the etched small-particle nickel powder and deionized water were mixed at a mass ratio of 0.2:1 and ultrasonically dispersed at 50℃ for 30 min at an ultrasonic frequency of 50 kHz. Then, 30 wt% ammonium heptamolybdate, 1 wt% tartaric acid and 2 wt% hydrazine hydrate were added, and the solution was heated to 70℃ and kept at the temperature for 1 h. During the reaction, the pH value was finely adjusted to 6 every 20 min with ammonia water.

[0073] (3) Under the protection of argon atmosphere, after the reaction of ammonium heptamolybdate is completed, 10wt% ammonium paratungstate, 1wt% sodium pyrophosphate and 2wt% hydrazine hydrate are added to the solution and the reaction is kept at 70℃ for 0.5h. During the reaction, the pH value is adjusted to 9 every 20min with ammonia water.

[0074] (4) After the ammonium paratungstate reaction is completed, filter the powder and then wash it twice with deionized water. Place it in a vacuum drying oven and vacuum dry it at 80°C for 2 h to obtain small-particle-size composite nickel powder (i.e., nickel-based composite powder) with uniform surface loading of active elements.

[0075] X-ray fluorescence spectroscopy (XRF) analysis revealed that the small-particle-size composite nickel powder contained 10 wt% molybdenum and 5 wt% tungsten.

[0076] S2. The small-particle-size composite nickel powder obtained in step S1 is subjected to spray granulation and atmosphere sintering to obtain nickel-based multi-component composite powder. The specific steps are as follows: Preparation of slurry: Weigh 30% small particle size composite nickel powder, 0.1% aluminum powder (particle size 1-3μm), 5% carbonyl nickel powder, 0.5% polyvinyl alcohol, and 0.1% polyethylene glycol by mass, and add them sequentially to 64.3% deionized water. Stir at 200 r / min for 60 min to form a slurry.

[0077] The above slurry was sprayed and granulated using a centrifugal spray granulator. The process parameters included: centrifugal head rotation frequency of 250 Hz, inlet air temperature of 150 ℃, outlet air temperature of 90 ℃, feed rate of 10 rpm, and atomization pressure of 0.1 MPa.

[0078] The spherical powder after spray granulation was subjected to segmented atmosphere (argon) sintering. First, the temperature was slowly increased from room temperature to 550℃ at a heating rate of 5℃ / min and held for 0.5 h; then, the temperature was slowly increased to 950℃ at a heating rate of 3℃ / min and held for 0.5 h; finally, the powder was cooled to room temperature in the furnace to obtain nickel-based multi-component composite powder that meets the requirements of plasma spray coating.

[0079] S3. A nickel-based multi-component composite powder is deposited on the surface of a nickel mesh substrate using plasma spraying technology to obtain a porous Ni-based coated electrode.

[0080] A woven nickel mesh with a mesh size of 30 mesh (wire diameter 0.18 mm) and a length of 400 mm × width was selected as the substrate and sandblasted. The sandblasting pressure was 0.3 MPa and the sandblasting angle was 30°.

[0081] The sandblasted nickel mesh was then subjected to plasma spraying. Key parameters included: spraying power of 40kW, powder feed rate of 150g / min, spraying distance of 150mm, spraying angle of 30°, hydrogen flow rate of 5L / min, and a single powder feeder with three feeders. During the spraying process, three compressed air pipes moved with the spray gun, with a gas pressure of 0.6MPa. After two cycles of spraying, a Ni-3wt%Mo-1.5wt%W-0.1wt%Al multi-element coating electrode (i.e., a multi-element metal-doped nickel-based coating electrode) was obtained.

[0082] Testing revealed that the nickel-based coated electrode obtained in this embodiment contained 2.88 wt% nickel oxide and exhibited an ultrasonic weight loss of 1.38 mg / cm³. 2 (Test parameters: 20wt% KOH solution, ultrasonic temperature 60℃, ultrasonic duration 120min); Chamber voltage 1.718V (alkali concentration 30wt%, operating temperature 85±1℃, 4kA / m) 2 (Tested for 120 hours under current density conditions).

[0083] Example 3 like Figure 1 As shown, the preparation method of the multi-metal doped nickel-based coated electrode (Ni-15wt%Mo-5wt%W-2wt%Al) in this embodiment is as follows: S1. Roughening treatment: Active refractory metal elements are deposited on the surface of small-particle-size nickel powder using chemical deposition.

[0084] (1) Under the protection of argon atmosphere, small-particle-size nickel powder (average particle size 2.2 μm) was dispersed in a weak acid solution with a solid content of 50 wt% for etching treatment. The weak acid solution included 10 wt% citric acid, 20 wt% anhydrous ethanol and 70 wt% deionized water, the etching temperature was 60 °C and the etching time was 20 min.

[0085] (2) Under the protection of argon atmosphere, the etched small-particle nickel powder and deionized water were mixed at a mass ratio of 1:1 and ultrasonically dispersed at 40℃ for 20 min at an ultrasonic frequency of 40 kHz. Then, 70 wt% ammonium heptamolybdate, 5 wt% tartaric acid and 1.0 wt% hydrazine hydrate were added, and the solution was heated to 85℃ and kept at the temperature for 3 h. During the reaction, the pH value was finely adjusted to 4 every 10 min with ammonia water.

[0086] (3) Under the protection of argon atmosphere, after the reaction of ammonium heptamolybdate is completed, 30wt% ammonium paratungstate, 5wt% sodium pyrophosphate and 10wt% hydrazine hydrate are added to the solution and the reaction is kept at 85℃ for 1.5h. During the reaction, the pH value is adjusted to 8 every 10min with ammonia water.

[0087] (4) After the ammonium paratungstate reaction is completed, filter the powder and then wash it with deionized water four times. Place it in a vacuum drying oven and dry it under vacuum at 80°C for 2 h to obtain small-particle-size composite nickel powder (i.e., nickel-based composite powder) with uniform surface loading of active elements.

[0088] The small-particle-size composite nickel powder obtained by X-ray fluorescence spectroscopy (XRF) contains 30 wt% molybdenum and 10 wt% tungsten.

[0089] S2. The small-particle-size composite nickel powder obtained in step S1 is subjected to spray granulation and atmosphere sintering to obtain nickel-based multi-component composite powder. The specific steps are as follows: Preparation of slurry: Weigh 50% small particle size composite nickel powder, 2% aluminum powder (particle size 1-3μm), 10% carbonyl nickel powder, 5% polyvinyl alcohol, and 2% polyethylene glycol by mass, and add them sequentially to 31% deionized water. Stir at 200r / min for 120min to form a slurry.

[0090] The above slurry was sprayed and granulated using a centrifugal spray granulator. The process parameters included: centrifugal head rotation frequency of 350 Hz, inlet air temperature of 250 ℃, outlet air temperature of 150 ℃, feed rate of 30 rpm, and atomization pressure of 0.3 MPa.

[0091] The spherical powder after spray granulation was subjected to segmented atmosphere (argon) sintering. First, the temperature was slowly increased from room temperature to 550℃ at a heating rate of 10℃ / min and held for 1 hour; then, the temperature was slowly increased to 1150℃ at a heating rate of 5℃ / min and held for 2 hours; finally, the powder was cooled to room temperature in the furnace to obtain nickel-based multi-component composite powder that meets the requirements of plasma spray coating.

[0092] S3. A nickel-based multi-component composite powder is deposited on the surface of a nickel mesh substrate using plasma spraying technology to obtain a porous Ni-based coated electrode.

[0093] A stretched nickel mesh measuring 0.15mm (thickness) × 0.15mm (rib) and 400mm (length) × 400mm (width) was selected as the substrate and sandblasted at a pressure of 0.7MPa and an angle of 70°.

[0094] The sandblasted nickel mesh was then subjected to plasma spraying. Key parameters included: spraying power of 55kW, powder feed rate of 300g / min, spraying distance of 180mm, spraying angle of 70°, hydrogen flow rate of 12L / min, and a single powder feeder with three feeders. During the spraying process, three compressed air pipes moved with the spray gun, with a gas pressure of 0.6MPa. After two cycles of spraying, a Ni-15wt%Mo-5wt%W-2wt%Al multi-element coating electrode (i.e., a multi-element metal-doped nickel-based coating electrode) was obtained.

[0095] Testing revealed that the nickel-based coated electrode obtained in this embodiment contained 2.95 wt% nickel oxide and exhibited an ultrasonic weight loss of 1.64 mg / cm³. 2 (Test parameters: 20wt% KOH solution, ultrasonic temperature 60℃, ultrasonic duration 120min); Chamber voltage 1.720V (alkali concentration 30wt%, operating temperature 85±1℃, 4kA / m) 2 (Tested for 120 hours under current density conditions).

[0096] Example 4 Compared with Example 1, the nickel mesh shape in this example is a corrugated mesh, and the other steps and parameters are the same as in Example 1.

[0097] Testing revealed that the nickel-based coated electrode obtained in this embodiment contained 2.91 wt% nickel oxide and exhibited an ultrasonic weight loss of 1.66 mg / cm³. 2 (Test parameters: 20wt% KOH solution, ultrasonic temperature 60℃, ultrasonic duration 120min); Chamber voltage 1.712V (alkali concentration 30wt%, operating temperature 85±1℃, 4kA / m) 2 (Tested for 120 hours under current density conditions).

[0098] Example 5 Compared with Example 1, the nickel-shaped mesh in this example is a knitted mesh, and the other steps and parameters are the same as in Example 1.

[0099] Testing revealed that the nickel-based coated electrode obtained in this embodiment contained 2.86 wt% nickel oxide and exhibited an ultrasonic weight loss of 1.40 mg / cm³. 2 (Test parameters: 20wt% KOH solution, ultrasonic temperature 60℃, ultrasonic duration 120min); Chamber voltage 1.713V (alkali concentration 30wt%, operating temperature 85±1℃, 4kA / m) 2 (Tested for 120 hours under current density conditions).

[0100] Comparative Example 1 Compared with Example 1, in step S2 of this comparative example, no nickel carbonyl powder is added to the slurry, and all other steps and parameters are the same as in Example 1.

[0101] Testing revealed that the nickel-based multi-component composite powder sintered in this comparative atmosphere had poor sphericity, contained a large amount of broken powder, and had a wide particle size range.

[0102] like Figure 5 The image shown is a SEM image of the surface morphology of the nickel-based coated electrode with multi-metal doped coating, Comparative Example 1. From... Figure 5 It can be seen that there are large cracks on the surface of the coated electrode, indicating that the deposition effect is poor.

[0103] Testing revealed that the nickel-based coated electrode obtained in this comparative example contained 3.52 wt% nickel oxide, an increase of 23.9% compared to Example 1; and the ultrasonic weight loss was 4.53 mg / cm³. 2 The voltage of the small cell was 1.9 times higher than that of Example 1; the voltage of the small cell was 1.740V, which was 29mV higher than that of Example 1.

[0104] Based on the above results, this comparative example, due to not adopting the multi-metal synergistic doping scheme protected by this invention, resulted in a significant increase in nickel oxide content, exacerbating the electrode oxygen evolution side reaction; a surge in ultrasonic weight loss of 1.9 times, a sharp decrease in coating adhesion, and deterioration of long-term service stability; a 29mV increase in chamber voltage, reduced catalytic activity, increased cell voltage, and increased operating costs.

[0105] Comparative Example 2 Compared with Example 1, this comparative example uses 20wt% metallic molybdenum powder (particle size 1~3μm) instead of 50wt% industrial grade ammonium heptamolybdate, and uses 8wt% metallic tungsten powder (particle size 1~3μm) instead of 20wt% industrial grade ammonium paratungstate. All other steps and parameters are the same as in Example 1.

[0106] The raw material cost in Comparative Example 2 is 58% higher than that in Example 1, which significantly increases the cost of electrode preparation.

[0107] Testing revealed that the molybdenum and tungsten elements in the nickel-based multi-element composite powder sintered in the comparative atmosphere were unevenly distributed and exhibited significant agglomeration, which affected the catalytic activity of the electrode.

[0108] Testing revealed that the nickel-based coated electrode obtained in this comparative example exhibited severe molybdenum and tungsten agglomeration and uneven pore distribution; the chamber voltage reached 1.758V, an increase of 47mV compared to Example 1; the nickel oxide content was 3.87wt%; and the ultrasonic weight loss was 3.53mg / cm³. 2 .

[0109] Comparative Example 3 Compared with Example 1, this comparative example omits the step of depositing molybdenum and tungsten active elements on the surface of small-particle nickel powder after etching, and deletes steps (2) and (3) of step S1. After washing the etched small-particle nickel powder with deionized water and vacuum drying, it is then subjected to steps such as slurry preparation, spray granulation, sintering and coating spraying, with the specific parameters remaining unchanged.

[0110] Testing revealed that the ultrasonic weight loss in the nickel-based coated electrode obtained in this comparative example was 4.32 mg / cm³. 2 The nickel oxide content was 3.95 wt%; the chamber voltage reached 1.746 V, which was 35 mV higher than that of Example 1.

[0111] Comparative Example 4 Compared to Example 1, the atmosphere sintering method in this comparative example is a single-step sintering, that is, under the protection of an inert atmosphere, the temperature is directly heated from room temperature to 1000°C and held for 1 hour, with a heating rate of 10°C / min. All other steps and parameters are the same as in the example.

[0112] like Figure 6 As shown, the nickel-based multi-component composite powder obtained after atmospheric sintering in this comparative example contains a large number of irregular spherical powders and a small amount of broken powders, and the sphericity is significantly different from that in Example 1.

[0113] Testing revealed that the ultrasonic weight loss in the nickel-based coated electrode obtained in this comparative example was 3.65 mg / cm³. 2 The nickel oxide content is 4.51 wt%; the chamber voltage reaches 1.758 V.

[0114] Comparative Example 5 Compared with Example 1, the aluminum powder content with a particle size of 1-3 μm in this comparative example is increased by 5 wt%, and the spraying angle in the plasma spraying parameters is set to 90°, the powder feeding method is single-channel single-path, and other steps and parameters are the same as in the example.

[0115] like Figure 7 The image shown is a cross-sectional optical view of the nickel-based coated electrode with a multi-metal doped structure, as shown in Comparative Example 5. From... Figure 6 As can be seen, the internal pore distribution of the nickel-based coating in this comparative example is uneven, and the coating deposition uniformity is poor, with some areas even lacking coating coverage, indicating poor coating deposition quality.

[0116] Testing revealed that the ultrasonic weight loss in the nickel-based coated electrode obtained in this comparative example was 3.74 mg / cm³. 2 The nickel oxide content was 4.63 wt%; the chamber voltage reached 1.769 mV, which was 58 mV higher than that of Example 1.

[0117] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a nickel-based coated electrode doped with a multi-metal element, characterized in that, Includes the following steps: S1. Molybdenum and tungsten active metal elements are deposited onto the surface of etched nickel powder to form a nickel-based composite powder, wherein the molybdenum content is 10-30 wt% and the tungsten content is 5-10 wt%; the particle size of the unetched nickel powder is ≤5 μm; S2. Add nickel-based composite powder, aluminum powder, nickel powder particles with a particle size of not less than 5μm, binder and dispersant to deionized water and stir to form a slurry. Then, spray granulation and atmosphere sintering are performed to obtain nickel-based multi-component composite powder. S3. The nickel-based multi-component composite powder is deposited onto the surface of a nickel mesh substrate to obtain the multi-metal doped nickel-based coated electrode.

2. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, The preparation method of the nickel-based composite powder is as follows: Under an inert atmosphere, etched nickel powder is dispersed in deionized water to form a suspension. Then, ammonium heptamolybdate, tartaric acid, and hydrazine hydrate are added, and the mixture is heated to 70–85°C and kept at this temperature for 1–3 hours. During the reaction, the pH value is adjusted to 4–6 to form a molybdenum-nickel mixture. Ammonium paratungstate, sodium pyrophosphate, and a reducing agent are then added, and the mixture is kept at 70–85°C for 0.5–1.5 hours. During the reaction, the pH value is adjusted to 8–9. Finally, the reacted powder is washed and dried to obtain the nickel-based composite powder.

3. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 2, characterized in that, The mass ratio of the etched nickel powder to deionized water is 0.2–1.0:1; Based on the mass of etched nickel powder, the amount of ammonium heptamolybdate used is 30-70%, the amount of tartaric acid used is 1-5%, and the amount of hydrazine hydrate used is 2-10%. Based on the mass of etched nickel powder, the amount of ammonium paratungstate used is 10-30%, the amount of sodium pyrophosphate used is 1-5%, and the amount of reducing agent used is 2-10%.

4. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, The nickel powder has a particle size of 0.5–3 μm; The nickel powder is etched using a weak acid solution in an inert atmosphere at a temperature of 30–60°C for 5–20 minutes. The amount of nickel powder added is 10-50% of the total mass of the nickel powder and the weak acid solution; The composition of the weak acid solution is: 1-10 wt% citric acid, 5-20 wt% anhydrous ethanol, and the balance being deionized water.

5. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, In step S2, the slurry is composed of the following raw materials in the following mass percentages: 30-50% nickel-based composite powder, 0.1-2.0% aluminum powder, 5-10% nickel powder particles, 0.5-5.0% binder, 0.1-2.0% dispersant, and the balance being deionized water; The nickel powder particles are carbonyl nickel powder with a particle size of 5-10 μm; The aluminum powder is spherical with a particle size of 1–3 μm.

6. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, In step S2, the process parameters for spray granulation are: centrifuge head rotation frequency 250-350Hz, inlet air temperature 150-250℃, outlet air temperature 90-150℃, feed rate 10-30rpm, and atomization pressure 0.1-0.3MPa.

7. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, In step S2, the atmosphere sintering is carried out in a segmented sintering under an inert atmosphere. The segmented sintering process is as follows: the temperature is raised from room temperature to 550°C at a rate of 5-10°C / min and held for 0.5-1.0 h; then the temperature is raised to 950-1150°C at a rate of 3-5°C / min and held for 0.5-2.0 h.

8. The method for preparing a multi-metal doped nickel-based coated electrode according to claim 1, characterized in that, In step S3, the nickel-based multi-component composite powder is deposited onto the surface of the nickel mesh substrate by plasma spraying. The process parameters of plasma spraying are: spraying power 40-55kW; powder feeding rate 150-300g / min; spraying distance 150-180mm; spraying angle 30-70°; hydrogen flow rate 5-12L / min. During the plasma spraying process, 2 to 4 compressed air pipes are arranged to move with the spray gun, and the gas pressure is 0.5 to 0.8 MPa.

9. A multi-metal doped nickel-based coated electrode, characterized in that, It is prepared by the method for preparing a multi-metal doped nickel-based coated electrode according to any one of claims 1-8.

10. The application of a multi-metal doped nickel-based coated electrode as described in claim 9 in alkaline water electrolysis for hydrogen production.

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