Preparation method and application of bimetallic phosphide coupled layered double hydroxide electrocatalyst

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production catalysts, and particularly relates to a preparation method and application of a bimetallic phosphide coupling layered double hydroxide electrocatalyst. The preparation method comprises the following steps: by taking a nickel source, an iron source, ammonium fluoride and urea as reactants, carrying out hydrothermal reaction to form a nickel-iron layered double hydroxide nano-catalyst precursor on a conductive substrate; and carrying out phosphating treatment on the nickel-iron layered double hydroxide nano-catalyst precursor by an electrodeposition method to obtain the bimetallic phosphide coupled layered double hydroxide electrocatalyst. Under the 1M potassium hydroxide solution test condition, the overpotential required by the catalyst is 89 mV when the current density in a linear scanning voltammetry curve is 10 mA cm <-2 >, and the catalyst is high in stability, simple in manufacturing process, energy-saving, suitable for industrial application and capable of being used for large-scale water electrolysis hydrogen production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytic water hydrogen production catalysts, and more specifically relates to a preparation method and application of a bimetallic phosphide coupled layered double hydroxide electrocatalyst. Background Art

[0002] As a green clean energy, hydrogen energy is considered to have broad development potential due to its high energy density and low pollution emissions. To solve the problems of high pollution and unsustainability of traditional hydrogen production technologies (such as steam reforming of CH4 and hydrogen production from industrial by-products), electrolytic water hydrogen production technology has emerged. In recent years, in order to minimize the low conversion efficiency and additional supply costs caused by overcoming high energy barriers in alkaline electrolytic water hydrogen production, it is crucial to develop various high-efficiency and stable catalysts. Currently, the noble metal Pt is still the most advanced catalyst, but its scarcity and high price obviously cannot meet the needs of large-scale hydrogen production. Therefore, people are committed to exploring non-noble metal-based electrocatalysts for hydrogen evolution reaction (HER).

[0003] Transition metal-based phosphide (TMPs) catalysts, due to their inherent catalytic activity and strong covalent bond between P and O, help to accelerate the oxidation of metal substances and improve the long-term stability of the catalyst. In addition, TMPs have excellent surface wettability, which is beneficial to promoting the contact between the catalyst and the electrolyte, showing performance comparable to that of platinum catalysts. In recent years, nickel-iron layered double hydroxide (NiFe-LDH) has been widely studied due to its strong electronegativity. After surface modification, some materials show excellent hydrogen evolution performance. However, most double-layer hydroxides still have disadvantages such as poor electron conductivity and limited active sites. Therefore, it is urgent to explore a simple non-noble metal catalyst with high activity and stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a bimetallic phosphide coupled layered double hydroxide electrocatalyst. By preparing a self-supporting NiCoP / NiFe-LDH catalyst, the problems existing in the above-mentioned prior art are solved, and a catalyst with high catalytic activity and good stability is prepared.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] One of the technical solutions of the present invention: Provide a preparation method of a bimetallic phosphide coupled layered double hydroxide electrocatalyst, and the steps include:

[0007] Using a first nickel source, an iron source, ammonium fluoride, and urea as reactants, through a hydrothermal reaction, a nickel-iron layered double hydroxide nanocatalyst precursor (NiFe-LDH precursor) is formed on a conductive substrate;

[0008] The nickel-iron layered double hydroxide nanocatalyst precursor is phosphated by an electrodeposition method to obtain a bimetallic phosphide-coupled layered double hydroxide electrocatalyst (NiCoP / NiFe-LDH heterostructure catalyst).

[0009] In the present invention, the nickel-iron layered double hydroxide nanocatalyst precursor is phosphated by an electrodeposition method, avoiding the release of harmful gases such as PH3.

[0010] Furthermore, the molar ratio of the first nickel source, iron source, ammonium fluoride, and urea is (0.5 - 5):(0.5 - 10):(0.5 - 10):(0.5 - 10).

[0011] Optionally, the molar ratio of the first nickel source, iron source, ammonium fluoride, and urea is 2.5:1.5:6:8.

[0012] Furthermore, the first nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel sulfate hexahydrate.

[0013] Optionally, the first nickel source is nickel chloride hexahydrate.

[0014] Furthermore, the iron source includes at least one of iron nitrate nonahydrate, iron chloride hexahydrate, and iron sulfate nonahydrate.

[0015] Optionally, the iron source is iron nitrate nonahydrate.

[0016] Furthermore, the temperature of the hydrothermal reaction is 90 - 120 °C, and the time is 8 - 20 h.

[0017] Optionally, the temperature of the hydrothermal reaction is 120 °C, and the time is 12 h.

[0018] The solvent in the hydrothermal treatment is deionized water, which is simple to prepare, green and environmentally friendly. After the hydrothermal reaction, the obtained NiFe-LDH precursor structure is in the shape of nanoflowers.

[0019] Furthermore, the parameters of the electrodeposition method include: voltage -2~-4 V, and time 100 - 3600 s.

[0020] Optionally, the parameters of the electrodeposition method include: voltage -4 V, and time 1800 s.

[0021] Furthermore, the electrolyte used in the electrodeposition method is an aqueous mixed solution of potassium chloride, cobalt source, second nickel source, and phosphorus source.

[0022] Based on the electrolyte, the electrodeposition method can introduce other doped ions, and the catalyst can be improved by adjusting parameters such as deposition voltage, time, and solution concentration to meet the requirements of different practical application scenarios for the electrode.

[0023] Optionally, the molar ratio of the second nickel source, cobalt source, phosphorus source, potassium chloride, and water in the mixed aqueous solution is (0.001 - 0.01):(0.001 - 0.01):(0.01 - 0.1):(0.009 - 0.09):(3 - 4).

[0024] Preferably, the molar ratio of the second nickel source, cobalt source, phosphorus source, potassium chloride, and water in the mixed aqueous solution is 0.002:0.002:0.02:0.009:(3 - 4).

[0025] Optionally, the second nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel sulfate hexahydrate.

[0026] Optionally, the cobalt source includes at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, and cobalt sulfate heptahydrate.

[0027] Optionally, the phosphorus source includes sodium hypophosphite monohydrate and / or sodium dihydrogen phosphate dihydrate.

[0028] In the present invention, the target compound (nickel-iron layered double hydroxide) is grown on the surface of the conductive substrate through a hydrothermal reaction, and then a NiCoP / NiFe-LDH heterostructure catalyst is constructed by an electrodeposition method; potassium chloride is also added to the electrolyte used in the electrodeposition method of the present invention. By introducing chloride ions into the electrodeposition solution of the electrodeposition method, not only can the corrosion resistance of the electrode be improved, but also the pH value can be adjusted to increase the conductivity of the solution, thereby optimizing the electrodeposition process; the electrodeposition is carried out by the constant voltage method. When a negative voltage is applied, the deposition and phosphating processes proceed simultaneously. Ni 2+ , Co 2+ and H2PO2 - obtain electrons and are successively reduced to Ni 0 , Co 0 and P atoms. At the same time, phosphorylation occurs between Ni 0 , Co 0 and the in-situ generated P atoms to form a bimetallic phosphide. After electrodeposition, the surface structure of the precursor changes, and compact and dense smooth particles are formed on the basis of the nanoflowers, increasing the specific surface area, shortening the electron mass transfer distance, improving the conductivity, and further promoting the improvement of the catalytic efficiency; the doping of the target elements Ni, Co, and P optimizes the electronic structure of NiFe-LDH and improves the electrochemical activity and durability of the catalyst.

[0029] The second technical solution of the present invention: Provide a bimetallic phosphide-coupled layered double hydroxide electrocatalyst, which is prepared by the above preparation method.

[0030] The third technical solution of the present solution: Provide an application of the above-mentioned bimetallic phosphide-coupled layered double hydroxide electrocatalyst in alkaline water electrolysis for hydrogen evolution.

[0031] The present invention discloses the following technical effects:

[0032] The present invention synthesized a NiCoP / NiFe-LDH heterostructure catalyst directly grown on the surface of a conductive substrate by a hydrothermal-electrodeposition method. Under the test conditions of 1 M potassium hydroxide solution, the overpotential required for a current density of 10 mA cm -2 in the linear sweep voltammogram is 89 mV respectively. Moreover, this catalyst has high stability, a simple and energy-saving manufacturing process, is suitable for industrial application, and can be used for large-scale electrolytic water hydrogen production.

[0033] The present invention reduces the high-valent metal substance to a low-valent metal at the reduction potential of electrodeposition, improving the durability of the catalyst. By introducing non-metallic elements into metals Ni and Co to form a NiCoP / NiFe-LDH heterostructure, more catalytic active sites are exposed, and the hydrogen adsorption energy is reduced. Due to the synergistic effect between the bimetals, where Ni promotes the Volmer reaction and Co promotes the generation and release of H2, the surface charge state is regulated, the adsorption of reactants / intermediates / products is optimized, and the catalytic activity is improved. Description of the Drawings

[0034] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 SEM images of the NiFe-LDH precursor in Example 1 at different magnifications, where (a) is at low magnification and (b) is at high magnification.

[0036] Figure 2 SEM images of the NiCoP / NiFe-LDH heterostructure catalyst at different magnifications, where (a) is at low magnification and (b) is at high magnification.

[0037] Figure 3 Linear sweep voltammograms of NiCoP / NiFe-LDH / NF, Co2P / NiFe-LDH / NF, Ni2P / NiFe-LDH / NF, Pt / C, nickel foam (NF), and NiFe-LDH.

[0038] Figure 4Linear sweep voltammograms of NiCo / NF, NiCoP / NF, NiCoP / NiFe-LDH / NF-1200s, NiCoP / NiFe-LDH / NF-2400s, NiCoP / NiFe-LDH / NF, NiFe-LDH-2, NiFe-LDH-2.5 and NiFe-LDH-3.

[0039] Figure 5 Is the current-time response curve of the NiCoP / NiFe-LDH heterostructure catalyst. Detailed implementation mode

[0040] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0041] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0042] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0043] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation modes of the present invention specification, which are obvious to those skilled in the art. Other implementation modes obtained from the present invention specification are also obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0044] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0045] The raw materials and reagents used in the specific implementation scheme of the present invention are all commercially available products. The reagents are all of analytical grade and do not require any treatment before use.

[0046] In some specific embodiments, a preparation method of a bimetallic phosphide-coupled layered double hydroxide electrocatalyst (NiCoP / NiFe-LDH heterostructure catalyst) is provided, and the steps include:

[0047] Prepare the NiFe-LDH precursor by hydrothermal synthesis: dissolve the iron source and nickel source in deionized water, stir until completely dissolved, then add ammonium fluoride and urea and stir until a light green solution is formed. Transfer the prepared light green solution to a 100 mL reaction kettle liner; immediately place the pretreated conductive substrate vertically into the liner for hydrothermal reaction to obtain the NiFe-LDH precursor grown on the conductive substrate;

[0048] Synthesize the NiCoP / NiFe-LDH heterostructure catalyst by electrodeposition: use the NiFe-LDH precursor grown on the conductive substrate as the working electrode and a graphite rod as the counter electrode. Use an aqueous solution containing a nickel source, a cobalt source, a phosphorus source, and potassium chloride as the electrolyte. Under an applied voltage of -2 to -4 V, perform electrodeposition (at room temperature) for 100 to 3600 s, so as to directly grow NiCoP on the surface of the precursor, and then wash it three times repeatedly with ethanol and water to obtain the NiCoP / NiFe-LDH heterostructure catalyst.

[0049] In the specific embodiments of the present invention, nickel foam is used as an exemplary conductive substrate for specific elaboration, but nickel foam is not used as a further limitation to the present invention. The treatment process of nickel foam is as follows:

[0050] When using nickel foam as the substrate, cut the nickel foam into pieces of 4 - 8 square centimeters, first ultrasonically soak it in concentrated hydrochloric acid for 10 - 30 min to remove the surface oxide film and dirt; then ultrasonically clean it in water and absolute ethanol for 10 - 30 min until the pH is neutral; finally, place it in a vacuum drying oven for drying.

[0051] During the hydrothermal synthesis of the NIFe-LDH precursor, nickel on the surface of the nickel foam will be partially etched into Ni 2+ , Ni 2+ and Fe 3+ will undergo a coprecipitation reaction to form NiFe-LDH. To accurately synthesize the NiCo bimetallic phosphide of the present invention, it is necessary to continue to add a nickel source to ensure the successful preparation of the catalyst.

[0052] It should be noted that the parts not detailed in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0053] Example 1

[0054] The preparation steps of the bimetallic phosphide-coupled layered double hydroxide electrocatalyst (NiCoP / NiFe-LDH heterostructure catalyst) include:

[0055] S1. Preparation of NiFe-LDH precursor:

[0056] Weigh 0.606 g of Fe(NO3)3·9H2O and dissolve it in 70 mL of deionized water. Stir until completely dissolved, then add 0.594 g of NiCl2·6H2O and continue stirring for 15 min (the molar ratio of Fe(NO3)3·9H2O to NiCl2·6H2O is 1.5:2.5). Subsequently, add 0.222 g of NH4F and 0.480 g of CO(NH2)2, and stir the solution until it turns light green;

[0057] Transfer the light green mixed solution to a 100 mL hydrothermal reaction kettle. Vertically place the nickel foam (conductive substrate layer) with the oxide film removed in the mixed solution and conduct a hydrothermal reaction at 120 °C for 12 h. Then, after cooling to room temperature, take out the obtained sample, wash it repeatedly 3 times with absolute ethanol and water, and then place it in a vacuum drying oven at 80 °C for drying for 3 h to obtain the NiFe bimetallic hydroxide nanocatalyst precursor (NiFe-LDH precursor) grown on the conductive substrate, denoted as NiFe-LDH;

[0058] S2. Preparation of NiCoP / NiFe-LDH heterostructure catalyst:

[0059] Dissolve 2 mmol of NiCl2·6H2O, 2 mmol of Co(NO3)2·6H2O, 20 mmol of NaH2PO2·H2O, and 9 mmol of KCl in 60 mL of deionized water, and stir evenly to obtain the electrolyte;

[0060] Use the NiFe-LDH precursor obtained in step S1 as the working electrode and a graphite rod as the counter electrode to form a two-electrode system. Adopt the constant voltage method, apply an external voltage of -4 V at room temperature, and conduct electrodeposition preparation in the above electrolyte for 1800 s to grow NiCoP on the surface of the NiFe-LDH precursor. Then, wash it repeatedly 3 times with water and ethanol and place it in a vacuum drying oven at 60 °C for drying for 8 h to obtain the NiCoP / NiFe-LDH heterostructure catalyst, denoted as NiCoP / NiFe-LDH / NF.

[0061] Example 2

[0062] Compared with Example 1, the difference is that electrodeposition preparation is carried out in the above electrolyte for 1200 s, and the final product is NiCoP / NiFe-LDH / NF electrocatalyst, denoted as NiCoP / NiFe-LDH / NF-1200s.

[0063] Example 3

[0064] Compared with Example 1, the difference is that electrodeposition preparation is carried out in the above electrolyte for 2400 s, and the final product is NiCoP / NiFe-LDH / NF electrocatalyst, denoted as NiCoP / NiFe-LDH / NF-2400s.

[0065] Comparative Example 1

[0066] Compared with Example 1, the difference is that the electrolyte is prepared by dissolving 2 mmol NiCl2·6H2O, 20 mmol NaH2PO2·H2O and 9 mmol KCl in 60 mL of deionized water, and the final product is Ni2P / NiFe-LDH electrocatalyst, denoted as Ni2P / NiFe-LDH / NF.

[0067] Comparative Example 2

[0068] Compared with Example 1, the difference is that the electrolyte is prepared by dissolving 2 mmol Co(NO3)2·6H2O, 20 mmol NaH2PO2·H2O and 9 mmol KCl in 60 mL of deionized water, and the final product is Co2P / NiFe-LDH electrocatalyst, denoted as Co2P / NiFe-LDH / NF.

[0069] Comparative Example 3

[0070] Preparation of conventional Pt / C electrocatalyst:

[0071] Mix 5 mg of 20% Pt / C, 720 μL of deionized water, 250 μL of ethanol and 30 μL of Nafion (5.0 wt %) and ultrasonically treat for 30 min to obtain Pt / C catalyst electrode ink. Drop 50 μL of Pt / C catalyst electrode ink on nickel foam (1 cm × 1 cm) and dry at room temperature to obtain Pt / C electrocatalyst, denoted as Pt / C.

[0072] Comparative Example 4

[0073] Compared with Example 1, the difference is that the NiFe-LDH precursor was not prepared, and NiCoP was directly deposited on NF. The electrolyte was prepared by dissolving 2 mmol of Co(NO3)2·6H2O, 20 mmol of NaH2PO2·H2O, and 9 mmol of KCl in 60 mL of deionized water. The final product was the NiCoP / NF electrocatalyst, denoted as NiCoP / NF.

[0074] Comparative Example 5

[0075] Compared with Example 1, the difference is that the NiFe-LDH precursor was not prepared and the P element was not introduced, and NiCo was directly deposited on NF. The electrolyte was prepared by dissolving 2 mmol of Co(NO3)2·6H2O and 9 mmol of KCl in 60 mL of deionized water. The final product was the NiCo / NF electrocatalyst, denoted as NiCo / NF.

[0076] Comparative Example 6

[0077] Compared with Example 1, the difference is that when preparing the NiFe-LDH precursor, the Ni source was singly changed to 2 mmol, 2.5 mmol, and 3 mmol. The final products were the NiFe-LDH-2, NiFe-LDH-2.5, and NiFe-LDH-3 electrocatalysts, denoted as NiFe-LDH-2, NiFe-LDH-2.5, and NiFe-LDH-3.

[0078] Test Example

[0079] Figure 1 SEM images of NiFe-LDH / NF at different magnifications. Among them, (a) is at low magnification and (b) is at high magnification. It can be seen from the figure that NiFe-LDH was successfully grown on the smooth nickel skeleton, and at the same time, the nanoflower-like structure of the NiFe-LDH precursor was shown.

[0080] Figure 2 SEM images of NiCoP / NiFe-LDH / NF at different magnifications. Among them, (a) is at low magnification and (b) is at high magnification. It can be seen from the figure that the nickel foam skeleton further grew dense and compact smooth particles, having more catalytic active sites.

[0081] Using NiCoP / NiFe-LDH / NF, NiCoP / NiFe-LDH / NF-1200s, Co2P / NiFe-LDH / NF, Ni2P / NiFe-LDH / NF, Pt / C, nickel foam (NF), NiFe-LDH-2.5, NiFe-LDH-2, NiFe-LDH-3, NiCoP / NF, NiCo / NF, NiCoP / NiFe-LDH / NF-2400s, and NiFe-LDH as the working electrodes, Hg / HgO as the reference electrode, and a graphite rod as the auxiliary electrode, with an electrolyte of 1 mol L -1 KOH solution, and a scanning rate of 5 mV s -1 −1, linear sweep voltammetry tests were carried out on a Chenhua electrochemical workstation (CHI760E), and the results are as Figure 3 and Figure 4 shown.

[0082] Figure 3 are the linear sweep voltammograms of NiCoP / NiFe-LDH / NF, Co2P / NiFe-LDH / NF, Ni2P / NiFe-LDH / NF, Pt / C, nickel foam (NF), and NiFe-LDH.

[0083] Figure 4 are the linear sweep voltammograms of NiCo / NF, NiCoP / NF, NiCoP / NiFe-LDH / NF-1200s, NiCoP / NiFe-LDH / NF-2400s, NiCoP / NiFe-LDH / NF, NiFe-LDH-2, NiFe-LDH-2.5, and NiFe-LDH-3.

[0084] It can be seen from Figures 3 - 4 that through the synergistic effect between Ni and Co, the overpotential of the sample at 10 mA cm -2 −2 is significantly better than that of Comparative Example 1 and Comparative Example 2, indicating that the bimetallic phosphide-coupled layered double hydroxide electrocatalyst prepared by the method of the present invention has a faster H2 release process and electron / proton transfer steps, thus accelerating the entire HER process.

[0085] The obtained NiCoP / NiFe-LDH / NF sample was subjected to an I-T test at a potential of 10 mA cm -2 −2 to evaluate the long-term stability of the catalyst in alkaline solution, and the results are as Figure 5 shown.

[0086] Figure 5The current-time response curve of NiCoP / NiFe-LDH / NF. It can be seen from the figure that after continuous operation for 24 h, the current density remains almost unchanged, indicating its good stability.

[0087] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0088] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a bimetallic phosphide-coupled layered double hydroxide electrocatalyst, characterized in that the steps Including: Using a first nickel source, an iron source, ammonium fluoride, and urea as reactants, through hydrothermal reaction, a nickel-iron layered double hydroxide nanocatalyst precursor is formed on a conductive substrate; The nickel-iron layered double hydroxide nanocatalyst precursor is subjected to phosphating treatment by electrodeposition to obtain a bimetallic phosphide-coupled layered double hydroxide electrocatalyst; The electrolyte used in the electrodeposition method is an aqueous mixed solution of potassium chloride, a cobalt source, a second nickel source, and a phosphorus source.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the first nickel source, iron source, ammonium fluoride, and urea is (0.5 - 5):(0.5 - 10):(0.5 - 10):(0.5 - 10); and / or, the molar ratio of the second nickel source, cobalt source, phosphorus source, potassium chloride, and water in the aqueous mixed solution is (0.001 - 0.01):(0.001 - 0.01):(0.01 - 0.1):(0.009 - 0.09):(3 - 4).

3. The preparation method according to claim 1, characterized in that, The first nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel sulfate hexahydrate; and / or, the iron source includes at least one of iron nitrate nonahydrate, iron chloride hexahydrate, and iron sulfate nonahydrate.

4. The preparation method according to claim 1, characterized in that, The temperature of the hydrothermal reaction is 90 - 120 °C, and the time is 8 - 20 h.

5. The preparation method according to claim 1, characterized in that, The parameters of the electrodeposition method include: voltage -2~-4V, and the time is 100 - 3600 s.

6. The preparation method according to claim 1, wherein The second nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel sulfate hexahydrate.

7. The preparation method according to claim 1, characterized in that, The cobalt source includes at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, and cobalt sulfate heptahydrate.

8. The preparation method according to claim 1, characterized in that, The phosphorus source includes sodium hypophosphite monohydrate and / or sodium dihydrogen phosphate dihydrate.

9. A bimetallic phosphide-coupled layered double hydroxide electrocatalyst, characterized in that, The bimetallic phosphide-coupled layered double hydroxide electrocatalyst is prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the bimetallic phosphide-coupled layered double hydroxide electrocatalyst according to claim 9 in alkaline water electrolysis for hydrogen evolution.

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