Integrated electrode for in-situ growth of bimetallic phosphide on surface of square meter grade stainless steel, preparation method and application of integrated electrode

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production, and discloses a square meter grade stainless steel surface in-situ growth bimetallic phosphide integrated electrode and a preparation method and application thereof.The preparation method comprises the following steps that 1, a stainless steel substrate is subjected to ultrasonic cleaning with deionized water, acetone and ethyl alcohol in sequence and then heated and cleaned with a diluted hydrochloric acid solution, and the stainless steel substrate is dried; and finally, washing with deionized water to obtain a stainless steel substrate with a clean surface. (2) dissolving a phosphorus source and transition metal cation salt in an aqueous solution, and stirring at normal temperature to uniformly mix; and (3) putting the stainless steel mesh with the clean surface obtained in the step (1) into the metal salt solution obtained in the step (2) for heating reaction, washing an obtained sample with water after the reaction is finished, and drying. The preparation method has the advantages that the preparation process is simple, the cost is low, the reaction problem is low, the prepared integrated electrode has excellent electrocatalytic activity and stability, large-scale preparation can be achieved, and the integrated electrode is suitable for large-scale industrial hydrogen production through alkaline electrolysis of water.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolysis of water, and specifically relates to a square meter-level stainless steel surface modified integrated electrode formed by transition metal phosphating and its application in water electrolysis, and provides a method for preparing an electrode suitable for industrial water electrolysis hydrogen production with simple process and low cost. Background Art

[0002] In the context of economic globalization, the increasingly severe energy shortage and environmental pollution caused by fossil fuel consumption have become a huge obstacle to the harmonious development of mankind and nature. Human beings must change their dependence on the traditional fossil energy system and establish a new green energy structure. A very promising development direction is to use sustainable energy to convert atmospheric molecules (such as water, carbon dioxide and nitrogen) into higher value-added products (such as hydrogen, hydrocarbons and ammonia, etc.) through electrochemical conversion. Among them, the energy conversion system based on "water", "hydrogen" and "oxygen" can be regarded as a truly "zero-emission" clean energy conversion system. Among them, the electrocatalytic water decomposition hydrogen production technology can cooperate with renewable energy that is difficult to use, make full use of the intermittent and volatile renewable energy generation such as solar energy and wind energy, convert it into hydrogen and store it, and the purity of hydrogen is as high as 99.99% or more. However, the anodic oxygen evolution reaction (OER) and the cathode hydrogen evolution reaction (HER) of the water electrolysis hydrogen production system occur at the gas-solid-liquid three-phase interface, involving reactant diffusion, adsorption, reaction intermediate formation and conversion, product desorption, and charge transfer. The slow reaction kinetics and high reaction energy barriers severely limit the efficiency and service life of hydrogen production by water electrolysis. At present, the most ideal catalysts for HER and OER are precious metal Pt-based and RuO2 / IrO2-based materials, respectively. They have small reserves, high prices, and poor long-term stability during operation, which greatly limits the industrial application of water electrolysis hydrogen production. Therefore, it is crucial to develop transition metal-based catalysts with abundant resources, high activity, and low cost to reduce the cost of water electrolysis hydrogen production and improve hydrogen production efficiency.

[0003] Among the many non-precious metal electrocatalytic materials currently designed and developed, transition metal phosphides are considered to be one of the most likely options to replace precious metals and promote the application of clean energy technology due to their abundant resources, low price, diverse crystal structures, good electrochemical stability and potential multifunctional catalytic activity. Transition metals contain vacant d orbitals and unpaired d electrons, which can contact with reaction molecules to form characteristic chemical bonds on the d orbitals to achieve molecular activation, thereby reducing the activation energy of the reaction, which is the reason why such materials have electrocatalytic activity. Compared with traditional powder catalysts, monolithic electrodes do not require additional conductive agents and adhesives, reduce the interfacial resistance in the electrode and increase the utilization rate of active substances, thereby effectively improving the catalytic performance. In addition, the monolithic electrode has a three-dimensional porous structure, which can improve the mass transfer process of reactants and products and the gas diffusion process, and the monolithic electrode material can effectively improve the problems of catalyst shedding and dissolution in the actual reaction process, which also greatly improves the stability and efficiency of hydrogen production by water electrolysis. Therefore, we urgently need a non-precious metal-based integrated electrode that can achieve cheap, efficient and stable, so as to promote the large-scale industrial application of hydrogen production by water electrolysis. Summary of the invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention provides an integrated electrode for in-situ growth of bimetallic phosphide on a square meter level stainless steel surface, a preparation method and its application. The specific technical scheme is as follows: A square meter level stainless steel surface in-situ grown bimetallic phosphide integrated electrode has tiny particles grown on the stainless steel surface. The tiny particles are nickel hydrogen phosphite and iron hydrogen phosphate. The iron hydrogen phosphate and nickel hydrogen phosphite tiny particles are evenly distributed on the stainless steel surface.

[0005] Furthermore, the diameter of the microparticles is 50-100 um.

[0006] A method for preparing a square meter-level stainless steel surface in-situ grown bimetallic phosphide integrated electrode comprises the following steps: (1) Ultrasonic cleaning of the stainless steel substrate with deionized water, acetone, and ethanol in sequence; (2) heating and soaking the stainless steel substrate after ultrasonic cleaning in step (1) in a dilute hydrochloric acid solution; (3) After the acid leaching in step (2) is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; (4) dissolving two transition metal cation salts and a phosphorus source in an aqueous solution; (5) placing the solution prepared in step (4) at room temperature and stirring to mix evenly; (6) then placing the clean stainless steel substrate obtained in step (3) into the solution stirred in step (5) and heating it for reaction; (7) After the reaction in step (6) is completed, the sample obtained is washed with water and then dried to obtain the square meter-level stainless steel surface modified bimetallic phosphating integrated electrode.

[0007] Furthermore, the ultrasonic cleaning time in step (1) is 5 to 20 min.

[0008] Furthermore, the concentration of dilute hydrochloric acid in step (2) is 1 to 5 mol L -1 The acid leaching time is 1~8 h, and the acid leaching temperature is 50~80 ℃; the preferred acid leaching time is 2~6 h.

[0009] Furthermore, in step (4), the transition metal cation salt is at least one of chloride, nitrate, sulfate, carbonate or acetate of a transition metal cation; the metal cation is at least one of iron, cobalt, nickel, vanadium, chromium, tungsten, manganese or molybdenum; the phosphorus source is at least one of sodium hypophosphite, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, phosphorus trichloride and phosphate ester; preferably, the metal cation is iron and nickel; preferably, the phosphorus source is sodium hypophosphite; the molar ratio of phosphorus anion to transition metal cation is 1:3~3:1; wherein the molar ratio of the two transition metal cations is 1:4~1:0.

[0010] Furthermore, in step (5), the stirring time is 30 to 120 min, preferably 50 to 100 min.

[0011] Furthermore, in step (6), the reaction temperature is 60-100 °C, and the reaction time is 12-24 h.

[0012] Furthermore, in step (7), the mixture is dried at 30-100°C for 1-6 hours.

[0013] An application of the in-situ grown bimetallic phosphide integrated electrode on a square meter level stainless steel surface in an electrocatalytic reaction.

[0014] Compared with the prior art, the present invention has the following advantages: 1. The present invention directly phosphates the stainless steel surface with transition metals and phosphorus sources, and the formed transition metal phosphate has good catalytic activity and stability. The phosphide on the surface of the stainless steel integrated electrode is not easy to fall off during the reaction and can have a long service life.

[0015] 2. The ratio of metal cations and phosphorus anions of the present invention can be changed into different proportions, and the types and ratios of the two metal cations can also be flexibly adjusted. It has strong environmental adaptability, mild use conditions, and is easy to operate.

[0016] 3. The substrate of the present invention is stainless steel, which has low cost, simple process and easily controllable reaction conditions, making it suitable for large-scale industrial application of hydrogen production by water electrolysis.

[0017] 4. The electrode prepared by the present invention has excellent catalytic performance in the electrocatalytic decomposition of water and oxygen evolution system, which makes the electrode have broad prospects in the industrialization of hydrogen production by electrolysis of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 The scanning electron microscope (SEM) images of different scales of the square meter-level stainless steel integrated electrode in Example 1 are shown; Figure 2 The transmission electron microscope (TEM) and element distribution diagram of the square meter-level stainless steel integrated electrode in Example 1; Figure 3 This is a high-resolution transmission electron microscopy image (HRTEM) of a square meter-level stainless steel integrated electrode in Example 1; Figure 4 This is an X-ray diffraction (XRD) characterization diagram of the square meter-level stainless steel integrated electrode in Example 1; Figure 5 This is a diagram showing the application of the square meter-level stainless steel integrated electrode in the AEM electrolytic cell in Example 1; Figure 6 The performance diagram of Examples 1, 2 and Comparative Example 3 in the electrocatalytic water decomposition and oxygen evolution reaction; Figure 7 The performance diagram of Examples 1, 4, and 5 in the electrocatalytic water decomposition and oxygen evolution reaction. DETAILED DESCRIPTION

[0020] The preparation process of the present application is described in detail below through examples, but the scope of protection claimed in the present application is not limited to the following examples.

[0021] The method for preparing a square meter-level stainless steel surface in-situ grown bimetallic phosphide integrated electrode of the present invention comprises the following steps: (1) Ultrasonic cleaning of the stainless steel substrate was performed with deionized water, acetone, and ethanol for 5 to 20 min in sequence; (2) the stainless steel substrate after ultrasonic cleaning in step (1) is heated and soaked in a dilute hydrochloric acid solution, the concentration of the dilute hydrochloric acid is 1-5 mol L-1, the acid immersion time is 1-8 h, and the acid immersion temperature is 50-80 °C; preferably, the acid immersion time is 2-6 h; (3) After the acid leaching in step (2) is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; (4) dissolving two transition metal cation salts and a phosphorus source in an aqueous solution; preferably, the transition metal cation salt is a nitrate of a transition metal cation; preferably, the metal cation is iron and nickel; and preferably, the phosphorus source is sodium hypophosphite; In the solution, the molar ratio of phosphorus anions to transition metal cations is 1:3 to 3:1; wherein the molar ratio of the two transition metal cations is 1:4 to 1:0; (5) Stirring the solution prepared in step (4) at room temperature for 30 to 120 min to make it uniformly mixed; preferably, the stirring time is 50 to 100 min; (6) Then, the clean stainless steel substrate obtained in step (3) is placed in the solution stirred in step (5) and heated for reaction; the reaction temperature is 60-100 °C and the reaction time is 12-24 h; (7) After the reaction in step (6) is completed, the sample obtained is washed with water and dried at 30-100° C. for 1-6 h to obtain the square meter-level stainless steel surface modified bimetallic phosphating integrated electrode. Example 1

[0022] 1. Ultrasonic clean the stainless steel substrate with deionized water, acetone, and ethanol for 10 min in sequence; 2. After ultrasonic cleaning in step 1, heat and soak the stainless steel substrate in a dilute hydrochloric acid solution with a concentration of 3 mol L -1 , the acid leaching time was 4 h, and the acid leaching temperature was 60 ℃; 3. After the acid leaching in step 2 is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; 4. Dissolve 7.0384 g of anhydrous sodium hypophosphite, 8.7237 g of nickel nitrate hexahydrate and 4.0400 g of ferric nitrate nonahydrate in 20 ml of deionized water and mix well. 5. Stir the solution prepared in step 4 at room temperature for 80 min to mix evenly; 6. Then, the clean stainless steel substrate obtained in step 3 is placed in the solution stirred in step 5 and heated for reaction; the reaction temperature is 90 °C and the reaction time is 18 h; 7. After the reaction in step 6 is completed, the sample obtained is washed with water and dried at 60° C. for 2 h to obtain the stainless steel surface modified bimetallic phosphating integrated electrode.

[0023] like Figure 1 and Figure 2 As shown in the figure, both the scanning electron microscope image and the transmission electron microscope image show that the synthesized stainless steel surface modified bimetallic phosphating integrated electrode has a micro-particle structure, and the micro-particle structure is evenly distributed on the stainless steel surface. Figure 3 and Figure 4 As shown in the figure, the high-resolution transmission electron microscopy image combined with the X-ray diffraction spectrum shows that the tiny particles are nickel hydrogen phosphite and iron hydrogen phosphate. Figure 5 As shown, the stainless steel surface modified bimetallic phosphating integrated electrode can be prepared on a large area. Example 2

[0024] 1. Ultrasonic clean the stainless steel substrate with deionized water, acetone, and ethanol for 10 min in sequence; 2. After ultrasonic cleaning in step 1, heat and soak the stainless steel substrate in a dilute hydrochloric acid solution with a concentration of 3 mol L -1 , the acid leaching time was 4 h, and the acid leaching temperature was 60 ℃; 3. After the acid leaching in step 2 is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; 4. Dissolve 7.0384 g of anhydrous sodium hypophosphite, 2.9079 g of nickel nitrate hexahydrate and 12.1200 g of ferric nitrate nonahydrate in 20 ml of deionized water and mix well; 5. Stir the solution prepared in step 4 at room temperature for 80 min to mix evenly; 6. Then, the clean stainless steel substrate obtained in step 3 is placed in the solution stirred in step 5 and heated for reaction; the reaction temperature is 90 °C and the reaction time is 18 h; 7. After the reaction in step 6 is completed, the sample obtained is washed with water and dried at 60° C. for 2 h to obtain the stainless steel surface modified bimetallic phosphating integrated electrode.

[0025] Comparative Example 3 1. Ultrasonic clean the stainless steel substrate with deionized water, acetone, and ethanol for 10 min in sequence; 2. After ultrasonic cleaning in step 1, heat and soak the stainless steel substrate in a dilute hydrochloric acid solution with a concentration of 3 mol L -1 , the acid leaching time was 4 h, and the acid leaching temperature was 60 ℃; 3. After the acid leaching in step 2 is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; 4. Dissolve 7.0384 g of anhydrous sodium hypophosphite and 11.6316 g of nickel nitrate hexahydrate in 20 ml of deionized water and mix well; 5. Stir the solution prepared in step 4 at room temperature for 80 min to mix evenly; 6. Then, the clean stainless steel substrate obtained in step 3 is placed in the solution stirred in step 5 and heated for reaction; the reaction temperature is 90 °C and the reaction time is 18 h; 7. After the reaction in step 6 is completed, the sample obtained is washed with water and dried at 60° C. for 2 h to obtain the stainless steel surface modified metal phosphating integrated electrode.

[0026] Results and discussion: In Example 1, Example 2 and Comparative Example 3, under the premise of other conditions being the same (the amount of sodium hypophosphite and the ratio of sodium hypophosphite to metal cations, the amount of water and 90°C oven reaction for 18 h), the ratio of the two metal cations in the solution was adjusted by changing the amount of metal salt added. Example 4

[0027] 1. Ultrasonic clean the stainless steel substrate with deionized water, acetone, and ethanol for 10 min in sequence; 2. After ultrasonic cleaning in step 1, heat and soak the stainless steel substrate in a dilute hydrochloric acid solution with a concentration of 3 mol L -1 , the acid leaching time was 4 h, and the acid leaching temperature was 60 ℃; 3. After the acid leaching in step 2 is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; 4. Dissolve 3.5192 g of anhydrous sodium hypophosphite, 4.3618 g of nickel nitrate hexahydrate and 2.0200 g of ferric nitrate nonahydrate in 20 ml of deionized water and mix well; 5. Stir the solution prepared in step 4 at room temperature for 80 min to mix evenly; 6. Then, the clean stainless steel substrate obtained in step 3 is placed in the solution stirred in step 5 and heated for reaction; the reaction temperature is 90 °C and the reaction time is 18 h; 7. After the reaction in step 6 is completed, the sample obtained is washed with water and dried at 60° C. for 2 h to obtain the stainless steel surface modified bimetallic phosphating integrated electrode. Example 5

[0028] 1. Ultrasonic clean the stainless steel substrate with deionized water, acetone, and ethanol for 10 min in sequence; 2. After ultrasonic cleaning in step 1, heat and soak the stainless steel substrate in a dilute hydrochloric acid solution with a concentration of 3 mol L -1 , the acid leaching time was 4 h, and the acid leaching temperature was 60 ℃; 3. After the acid leaching in step 2 is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; 4. Dissolve 10.5576 g of anhydrous sodium hypophosphite, 4.3618 g of nickel nitrate hexahydrate and 18.1800 g of ferric nitrate nonahydrate in 20 ml of deionized water and mix well; 5. Stir the solution prepared in step 4 at room temperature for 80 min to mix evenly; 6. Then, the clean stainless steel substrate obtained in step 3 is placed in the solution stirred in step 5 and heated for reaction; the reaction temperature is 90 °C and the reaction time is 18 h; 7. After the reaction in step 6 is completed, the sample obtained is washed with water and dried at 60° C. for 2 h to obtain the stainless steel surface modified bimetallic phosphating integrated electrode.

[0029] Results and discussion: In Examples 1, 4, and 5, under the premise of other consistent conditions (ratio of sodium hypophosphite to metal cations, amount of water, and 90 °C oven reaction for 18 h), the concentrations of sodium hypophosphite and metal cations in the solution were adjusted by changing the addition amounts of sodium hypophosphite and metal salts.

[0030] Application Example 1 The stainless steel surface modified bimetallic phosphating integrated electrode obtained in Example 1, Example 2 and Comparative Example 3 was used as an integrated electrode for the oxidation reaction of the electrocatalytic water decomposition oxygen production system, and the effect of gradually changing the ratio of the two metal cations in the solution on the catalytic performance of the stainless steel surface modified bimetallic phosphating integrated electrode was investigated.

[0031] 1. Test system construction: The test device is a three-electrode system. The reference electrode is Hg / HgO (1M KOH solution), the counter electrode is a C rod, the working electrode is a 1*1 cm stainless steel surface modified bimetallic sulfide integrated electrode, and the electrolyte is 1M KOH solution.

[0032] 2. Catalytic performance evaluation method: The temperature of the electrolytic cell is maintained at 25 °C, and the ability of the catalyst to oxidize hydroxide anions (-OH) in the solution is tested by polarization curves to compare the potential required by the catalyst to reach a certain oxidation current density.

[0033] 3. The catalytic performance of the integrated electrode obtained by gradually changing the ratio of the two transition metal cations in the solution changes. The stainless steel surface modified metal phosphating integrated electrode (P-1) in Example 1 has the best catalytic performance compared with Example 2 (P-2) and Comparative Example 3 (P-3). Figure 6 As shown, at the same current density (100 mA cm -2), the overpotential of Example 1 (P-1) is 426 mV, the overpotential of Example 2 (P-2) is 485 mV, and the overpotential of Comparative Example 3 (P-3) is 502 mV. Therefore, the catalytic activity of the catalyst in the electrocatalytic decomposition of water and oxygen evolution reaction can be adjusted by adjusting the ratio of the two metal cations in the solution, thereby finding the optimal ratio.

[0034] Application Example 2 The stainless steel surface modified bimetallic phosphating integrated electrode obtained in Examples 1, 4 and 5 was used as an integrated electrode for the oxidation reaction of the electrocatalytic water decomposition oxygen production system, and the effect of gradually changing the concentration of sodium hypophosphite and metal cations in the solution on the catalytic performance of the stainless steel surface modified bimetallic phosphating integrated electrode was investigated.

[0035] 1. Test system construction: The test device is a three-electrode system. The reference electrode is Hg / HgO (1 M KOH solution), the counter electrode is a C rod, the working electrode is a 1*1 cm stainless steel surface modified bimetallic sulfide integrated electrode, and the electrolyte is 1 M KOH solution.

[0036] 2. Catalytic performance evaluation method: The temperature of the electrolytic cell is maintained at 25°C, and the ability of the catalyst to oxidize hydroxide ions (OH-) in the solution is tested by polarization curves, and the potential required by the catalyst to reach a certain oxidation current density is compared.

[0037] 3. The catalytic performance of the integrated electrode obtained by gradually changing the ratio and concentration of phosphorus and transition metal cations in the solution changes. The stainless steel surface modified metal phosphating integrated electrode (P-1) in Example 1 has the best catalytic performance compared with Example 4 (P-4) and Example 5 (P-5). Figure 7 As shown, at the same current density (100 mAcm -2 ), the overpotential of Example 1 (P-1) is 426 mV, the overpotential of Example 4 (P-4) is 454 mV, and the overpotential of Example 5 (P-5) is 473 mV. Therefore, the catalytic activity of the catalyst in the electrocatalytic decomposition of water and oxygen evolution reaction can be adjusted by adjusting the concentration of phosphorus and metal cations in the solution, thereby finding the optimal concentration.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A square meter level stainless steel surface in-situ grown bimetallic phosphide integrated electrode, characterized in that: Tiny particles grow on the surface of stainless steel. The tiny particles are nickel hydrogen phosphite and iron hydrogen phosphate. The iron hydrogen phosphate and nickel hydrogen phosphite tiny particles are evenly distributed on the surface of stainless steel.

2. The square meter level stainless steel surface in-situ grown bimetallic phosphide integrated electrode according to claim 1, characterized in that: The diameter of the tiny particles is 50-100 um.

3. A method for preparing a square meter level stainless steel surface in-situ grown bimetallic phosphide integrated electrode according to claim 1 or 2, characterized in that The following steps are involved: (1) Ultrasonic cleaning of the stainless steel substrate with deionized water, acetone, and ethanol in sequence; (2) heating and soaking the stainless steel substrate after ultrasonic cleaning in step (1) in a dilute hydrochloric acid solution; (3) After the acid leaching in step (2) is completed, the stainless steel substrate is rinsed with deionized water and then dried to obtain a stainless steel substrate with a clean surface; (4) dissolving two transition metal cation salts and a phosphorus source in an aqueous solution; (5) placing the solution prepared in step (4) at room temperature and stirring to mix evenly; (6) then placing the clean stainless steel substrate obtained in step (3) into the solution stirred in step (5) and heating it for reaction; (7) After the reaction in step (6) is completed, the sample obtained is washed with water and then dried to obtain the square meter-level stainless steel surface modified bimetallic phosphating integrated electrode.

4. The preparation method according to claim 3, characterized in that: The ultrasonic cleaning time in step (1) is 5 to 20 min.

5. The preparation method according to claim 3, characterized in that: The concentration of dilute hydrochloric acid in step (2) is 1-5 mol L -1 The acid leaching time is 1~8 h, and the acid leaching temperature is 50~80 ℃; the preferred acid leaching time is 2~6 h.

6. The preparation method according to claim 3, characterized in that: In step (4), the transition metal cation salt is at least one of chloride, nitrate, sulfate, carbonate or acetate of a transition metal cation; the metal cation is at least one of iron, cobalt, nickel, vanadium, chromium, tungsten, manganese or molybdenum; the phosphorus source is at least one of sodium hypophosphite, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, phosphorus trichloride and phosphate ester; preferably the metal cation is iron and nickel; preferably the phosphorus source is sodium hypophosphite; the molar ratio of phosphorus anion to transition metal cation is 1:3~3:1; wherein the molar ratio of the two transition metal cations is 1:4~1:

0.

7. The preparation method according to claim 3, characterized in that: In step (5), the stirring time is 30 to 120 min, preferably 50 to 100 min.

8. The preparation method according to claim 3, characterized in that: In step (6), the reaction temperature is 60-100 °C and the reaction time is 12-24 h.

9. The preparation method according to claim 3, characterized in that: In step (7), the mixture is dried at 30-100°C for 1-6 hours.

10. Use of the one-piece electrode with bimetallic phosphide grown in situ on a square meter level stainless steel surface according to claim 1 or 2 in an electrocatalytic reaction.

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