A method for synthesizing high-entropy metal phosphide catalytic materials

Abstract

The application discloses a method for synthesizing high-entropy metal phosphide catalytic material and belongs to the field of catalytic material. Specifically, metal salt is mixed with an alkali source, a substrate is added, and hydroxide is grown on the substrate by using a hydrothermal reaction; then, a mixed solution of metal salt and a chelating agent is mixed with a mixed solution of ferricyanide and cobalt cyanide, the substrate after the reaction is added, and a Prussian blue analogue precursor is grown on the substrate under the condition of a certain temperature; the obtained precursor is washed and dried, and then is subjected to continuous two-step calcination in a nitrogen-argon mixed gas; after the calcination is completed, a target product is obtained. The Prussian blue derivative metal phosphide catalytic material product obtained by using the application has high chemical stability and excellent electrocatalytic performance, and the preparation method has the characteristics of simple process flow, low cost, and high product yield.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials and relates to a method for preparing a novel catalytic material, specifically a method for synthesizing high-entropy metal phosphide catalytic materials. Background Technology

[0002] Currently, electrocatalytic water splitting is an effective way to solve energy and environmental problems. However, most of the better commercial materials in the field of electrocatalysis are precious metals. For example, for the oxygen evolution reaction (OER) half-reaction in electrocatalytic water splitting, commonly used commercial catalysts are ruthenium dioxide and iridium dioxide precious metal catalysts, but their high cost makes them unsuitable for large-scale industrial production. Therefore, the preparation of high-performance, low-cost non-precious metal catalysts is an urgent problem to be solved in the electrochemical industry. [1,2] For conventional electrochemical reactions, the activity of an electrocatalyst mainly depends on its conductivity, the number of exposed active sites, and the intrinsic activity of the active sites.

[0003] Prussian blue analogues (PBAs) are typical metal-organic framework materials, usually represented by the chemical formula A. x M[Q(CN)6] y The symbol is represented by A, where A represents an alkaline earth metal element, and M and N represent transition metal elements coordinated with nitrogen and carbon, respectively. [3] The cyanide ion of PBA can coordinate with many metal elements to form polymetallic Prussian blue analogs, thus it is widely used in the preparation of polymetallic compounds. However, PBA materials have poor electrical conductivity, which still limits their practical applications. Therefore, many studies have carried out derivatization treatments on PBA, such as sulfidation, phosphating, and selenization, to expose more active sites, enhance porosity, and improve conductivity to obtain better catalytic materials. [4–6]

[0004] Existing research has found that when phosphorus combines with metal elements, the interaction forces between metal atoms decrease, and the d-band shrinks, giving it properties similar to noble metals and enabling it to act as a highly efficient electrochemical catalyst. [7,8] Although many phosphides have shown good electrochemical activity in current research, the performance of metal phosphide materials is affected by many factors such as morphology and conductivity, and the ease of synthesis also affects whether the materials can be mass-produced. Furthermore, their poor stability, unable to maintain long-term stable catalysis under high currents (e.g., 0.5A-2A), limits their industrial application prospects.

[0005] To improve the chemical performance and stability of catalytic materials, an effective approach is currently entropy stabilization. Entropy stabilization often involves preparing high-entropy materials, defined by the configurational entropy of the components. However, with ongoing research, the definition of high-entropy materials is no longer limited to the magnitude of the entropy value. For example, some now also define high-entropy materials as those containing five or more metal components without phase separation. Compared to ordinary materials, high-entropy materials possess a stable single-phase solid solution structure, and because different metal elements randomly occupy metal sites within the same crystal lattice, their synergistic effects are stronger. Due to these unique crystal structures and elemental diversity, high-entropy materials are considered promising electrocatalysts, exhibiting greater catalytic activity. Currently, high-entropy materials are categorized into high-entropy alloys and high-entropy compounds.

[0006] The preparation of high-entropy transition metal phosphides not only provides a wider variety of electrochemical active sites but also maintains the stability of catalytic performance. Currently, research on the preparation of high-entropy phosphides is still limited and in its early stages. In existing research, Lai et al. [9] Five-element high-entropy NiCoFeMnCrP was prepared using the sol-gel method and calcination phosphating in a hydrogen-argon mixture. Its performance at 10 mA cm⁻¹ was [not specified]. -2 The overpotential is only 272 mV, and the Tafel slope is only 52.5 mV. -1 Zhou et al.

[10] Carbon-composite FeCoNiCuMnP synthesized using hydrothermal and calcination phosphating methods x High-entropy phosphide materials require only an overpotential of 239 mV to maintain a current of 10 mA cm⁻¹. -2 The current density, with a Tafel slope of 72.5 mV dec -1 The methods described above are relatively complex and have high requirements for metal salts and phosphorus sources. Furthermore, the preparation of some high-entropy phosphides currently requires localized extreme conditions such as high temperature and high pressure. In addition, the combination of different metal elements with phosphorus is very difficult. These drawbacks limit the widespread application and use of high-entropy metal phosphides.

[0007] [1]HU E, FENG Y, NAI J, et al. Construction of hierarchical Ni–Co–Phollownanobricks with oriented nanosheets for efficient overall water splitting[J]. Energy&Environmental Science, 2018, 11(4):872–880.

[0008] [2]WEI B,FU Z,LEGUT D,et al.Rational design of highly stable andactive mxene-based bifunctional orr / oer double-atom catalysts[J].AdvancedMaterials,2021,33(40):2102595.

[0009] [3]YI H,QIN R,DING S,et al.Structure and properties of prussian blueanalogues in energy storage and conversion applications[J].AdvancedFunctional Materials,2021,31(6):2006970.

[0010] [4]JE J,LIM H,JUNG H W,et al.Ultrafast and ultrastableheteroarchitectured porous nanocube anode composed of cus / fes2embedded innitrogen-doped carbon for use in sodium-ion batteries[J].Small,2022,18(6):2105310.

[0011] [5]WANG Y,WANG Y,GAO H,et al.Interface-induced contraction of core–shell prussian blue analogues toward hollow Ni-Co-Fe phosphide nanoboxes forefficient oxygen evolution electrocatalysis[J].Chemical Engineering Journal,2023,451:138515.

[0012] [6]ZHANG L,RONG J,YANG Y,et al.Activated FeS2@NiS2 core–shellstructure boosting cascade reaction for superior electrocatalytic oxygenevolution[J].Small,2023,19(17):2207472.

[0013] [7]GE Z,FU B,ZHAO J,et al.A review of the electrocatalysts onhydrogen evolution reaction with an emphasis on Fe,Co and Ni-based phosphides[J].Journal of Materials Science,2020,55(29):14081–14104.

[0014] [8]BODHANKAR P M,SARAWADE P B,KUMAR P,et al.Nanostructured metalphosphide based catalysts for electrochemical water splitting:a review[J].Small,2022,18(21):2107572.

[0015] [9]LAI D,KANG Q,GAO F,et al.High-entropy effect of a metal phosphideon enhanced overall water splitting performance[J].Journal of MaterialsChemistry A,2021,9(33):17913–17922.

[0016]

[10] ZHOU Y,GAO L,CHEN H,et al.Fabrication of amorphous FeCoNiCuMnP Xhigh-entropy phosphide / carbon composites with a heterostructured fusiformmorphology for efficient oxygen evolution reaction[J].Journal of MaterialsScience&Technology,2024,168:62–70. Summary of the Invention

[0017] The purpose of this invention is to provide a method for synthesizing high-entropy metal phosphide catalytic materials, which can then be widely applied in scientific research and industrial production. The obtained high-entropy phosphide materials exhibit excellent electrocatalytic oxygen desorption performance from water, while also demonstrating good stability.

[0018] Technical solution

[0019] This invention provides a method for synthesizing high-entropy metal phosphide catalytic materials, wherein the method includes the following steps:

[0020] (1) A certain amount of metal salt (Fe salt, Co salt, Ni salt) and alkali source are dissolved in water and stirred evenly, then added to the substrate. After hydrothermal reaction, the substrate is taken out, washed and dried to obtain a substrate loaded with metal hydroxide.

[0021] (2) Dissolve a certain amount of metal salts (Fe salts, Co salts, Ni salts, Cu salts, Mn salts, Cr salts, Zn salts, etc.) in water with a chelating agent and stir until homogeneous to form a solution A containing metal ions;

[0022] (3) Dissolve a certain amount of ferricyanide and cobalt cyanide in water to obtain solution B containing cyanide ions;

[0023] (4) While stirring vigorously, slowly add solution B to solution A;

[0024] (5) After mixing the two, the synthesized substrate loaded with metal hydroxide is placed in the mixed solution of the previous step and stirred for a period of time, and then left to stand and age at a certain temperature for a period of time.

[0025] (6) Remove the solvent, take out the substrate, wash it thoroughly, and dry it to obtain a substrate on which a Prussian blue analogue is grown;

[0026] (7) The substrate and phosphorus source are placed in a tube furnace, a protective gas is introduced, and the substrate is calcined and kept warm at a certain temperature to obtain the final multi-metal phosphide grown on the substrate, namely the high-entropy metal phosphide catalytic material, which has high catalytic activity and stability.

[0027] Furthermore, in step (1), there are no particular restrictions on the type of substrate, as long as it has a certain conductivity. The types of substrates selected are nickel foam, copper foam, carbon cloth, carbon paper, stainless steel mesh, etc.

[0028] Further, in step (1), the metal salt is a mixture of several metal salts in any ratio, such as ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric chloride hexahydrate, cobalt chloride hexahydrate, and nickel chloride hexahydrate; the alkali source is not particularly limited, but under preferred conditions, a solid alkali source is selected, which is a mixture of urea and hexamethylenetetramungsten in any ratio; the ratio of the total molar amount of the metal salt to the molar amount of the alkali source is 8:1-1:8, and the water volume is 60-80 mL; the hydrothermal process is carried out in a hydrothermal reactor known in the art, and the hydrothermal conditions can be various conditions commonly used in the art; but in a preferred case, the hydrothermal conditions include a heating rate of 1-20℃ / min, a reaction temperature of 80-180℃, and a reaction time of 10-48 h.

[0029] Furthermore, in step (1), the washing process involves alternating between anhydrous ethanol and deionized water for 2-5 times; the drying temperature is 60℃, and the drying time is 6-24h.

[0030] Further, in step (2), the metal salt is a mixture of metal salts such as ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, copper nitrate trihydrate, manganese nitrate tetrahydrate, chromium nitrate nonahydrate, zinc nitrate hexahydrate, ferric chloride hexahydrate, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate, manganese chloride tetrahydrate, chromium chloride hexahydrate, and zinc chloride in any proportion, but the final mixture contains at least five metal ions; the chelating agent is a mixture of one or more of trisodium citrate dihydrate, ethylenediaminetetraacetic acid, and ethylenediamine, the molar ratio of the total amount of metal ions to the amount of chelating agent added is 8:1-1:10, the volume of water is 50-120mL, the mixing temperature is 20-35℃, the stirring time is 10-60min, forming solution A.

[0031] Further, in step (3), solution B is a mixture of potassium ferricyanide, sodium ferricyanide, or potassium cobalt cyanide in any ratio, the molar ratio of the total molar amount of the mixture of potassium ferricyanide, sodium ferricyanide, or potassium cobalt cyanide to the total molar amount of metal ions in solution A is 2:1-1:6, the volume of water is 50-120mL, the mixing temperature is 20-35℃, and the stirring time is 10-60min.

[0032] Furthermore, in step (4), the mixing temperature of liquids A and B is 15-30℃, and the stirring time is 1-4h.

[0033] Furthermore, in step (5), the stirring time is 1-4 hours, the aging temperature is 15-45°C, and the sedimentation time is 20-35 hours.

[0034] Furthermore, in step (6), the washing process involves alternating between deionized water and anhydrous ethanol for 2-5 times; the drying temperature is 60°C, and the drying time is 6-24 hours.

[0035] Further, in step (6), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 1-10 min; the washing process is to wash with anhydrous ethanol and deionized water alternately 2-5 times; the drying temperature is 60℃ and the drying time is 6-24 h.

[0036] Further, in step (7), the phosphorus source is sodium hypophosphite or ammonium dihydrogen phosphate. Under preferred conditions, sodium hypophosphite is selected as the phosphorus source; the mass ratio of the substrate to the phosphorus source is 1:1 to 1:20; and the protective gas is a nitrogen-argon mixture in any proportion.

[0037] Furthermore, in step (7), the calcination process is carried out in a tube furnace. The calcination process does not have a fixed temperature, as long as the metal phosphide is effectively generated; under preferred conditions, the heating rate is 0.5-5℃ / min, raised to 150-250℃, and held for 0-1.5h; then, the heating rate is 0.5-10℃ / min, raised to 300-400℃, and held for 0.5-3.5h.

[0038] The key technical point of this invention is that it prepares high-entropy phosphides and their precursors through an extremely simple method, which solves the problem of the difficulty in combining different metal elements with phosphorus elements during the preparation of high-entropy phosphides, and at the same time provides the possibility of preparing high-entropy compounds containing other non-metal elements.

[0039] The main technical feature of this invention is that the choice of substrate can be adjusted according to changes in the reaction system. Nickel hydroxide sheets are generated on the substrate before the PBA precursor is formed. Firstly, chemical bonds enhance stability. Secondly, compared to direct growth, more PBA precursors can be grown, resulting in more active sites and catalytic centers during subsequent phosphating, thus improving catalytic activity. Simultaneously, using PBA as the precursor for the final phosphide allows for a variety of metal salt types and combinations of any types and amounts to form stable single-phase solid solution compounds, exhibiting good oxygen evolution activity and stability. This invention features low cost, short synthesis process, simple method, excellent performance, and good stability, while providing a feasible approach for the synthesis of high-entropy metal phosphides.

[0040] This invention employs a very simple hydrothermal synthesis and room-temperature precipitation growth method, resulting in a simple and efficient process. First, based on the material's application characteristics, the corresponding transition metal element is mixed with an alkaline source under hydrothermal conditions to generate a metal hydroxide. Then, the corresponding transition metal element is precipitated with an organic ligand in a suitable solution at room temperature to synthesize a precursor, which is then grown on a substrate containing the metal hydroxide to obtain the precursor. The substrate and reactants are connected by chemical bonds. The obtained precursor is then placed in a high-temperature processing vessel (e.g., a tube furnace) and calcined in a nitrogen-argon mixture to finally obtain the desired Prussian blue-derived metal phosphide material. The final material exhibits stable structure and excellent electrocatalytic performance.

[0041] The process used in the material synthesis is safe and efficient (it only involves room temperature stirring and low temperature hydrothermal processes, without involving complex environments such as vacuum), the instruments are simple (the main instruments for room temperature deposition are beakers and centrifuges; the main instrument for calcination is a tube furnace), and the process has strong continuity.

[0042] This invention utilizes a high-entropy metal phosphide catalytic material synthesized hydrothermally and grown at room temperature via precipitation. This material exhibits high catalytic activity and stability, with a stable structure, regular morphology, and good electrochemical stability. At 50 mA cm⁻¹ -2 At a current density of only 266mV, an overpotential of only 67mV is required, while the Tafel slope is only 67mV dec. -1 Meanwhile, its electrochemical performance remained unchanged after 5000 CV cycles at 500 mA / cm². -2 After a 40-hour chronopotential stability test at a current density, the potential remained well maintained. Therefore, this synthesis method is expected to be widely applied in the research and production of novel catalyst materials. The material prepared by this invention has low cost and a simple synthesis process, making it suitable for large-scale production. Therefore, it has broader scientific research and practical value. Attached Figure Description

[0043] Figure 1 Scanning electron microscope image of high-entropy phosphide FeCoNiCuMnP;

[0044] Figure 2 Image showing the X-ray diffraction pattern of high-entropy phosphide FeCoNiCuMnP;

[0045] Figure 3 The OER linear sweep voltammetric spectrum of high-entropy phosphide FeCoNiCuMnP;

[0046] Figure 4 Tafel slope plot of OER for high-entropy phosphides FeCoNiCuMnP.

[0047] Figure 5For high-entropy phosphides FeCoNiCuMnP at 500 mA cm⁻¹ -2 The results of a 40-hour chronopotential stability test at a given current density are shown in the figure. Detailed Implementation

[0048] The embodiments of the present invention will be described in detail below with reference to the examples. Those skilled in the art will understand that the following examples are merely preferred embodiments of the present invention to facilitate a better understanding of the invention, and therefore should not be considered as limiting the scope of the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. Unless otherwise specified, the experimental methods in the following examples are conventional methods; the experimental materials used, unless otherwise specified, are all purchased from conventional biochemical reagent manufacturers.

[0049] In the following examples, centrifugation was performed using a benchtop high-speed centrifuge (XiangYi H-1650), scanning electron microscopy was performed using a field emission scanning electron microscope (GeminiSEM 360), and electrochemical performance was obtained using a Shanghai Chenhua electrochemical workstation (CHI 760E).

[0050] Example 1:

[0051] At 25℃, weigh 0.404g of ferric nitrate nonahydrate (1mmol), 0.119g of nickel chloride hexahydrate (0.5mmol), and 0.140g of hexamethylenetetrammonium (1mmol), dissolve them in 70mL of deionized water, and then place the solution in a hydrothermal reactor. Cut a 1cm section... -2Small-sized nickel foams were also placed in a hydrothermal reactor. The heating rate was 10℃ / min, the reaction temperature was 80℃, and the reaction time was 10h. After the reaction, the substrate was removed, washed, and dried for 24h. The following were weighed: 0.202g ferric nitrate nonahydrate (0.5mmol), 0.291g cobalt nitrate hexahydrate (1mmol), 0.238g cobalt chloride hexahydrate (1mmol), 0.291g nickel nitrate hexahydrate (1mmol), 0.119g nickel chloride hexahydrate (0.5mmol), 0.126g manganese nitrate tetrahydrate (0.5mmol), 0.297g zinc nitrate hexahydrate (1mol), and 0.882g trisodium citrate dihydrate (3mmol). Solution A was prepared by dissolving potassium ferricyanide (1 mmol) and sodium ferricyanide (1 mmol) in 100 mL of deionized water. Solutions A and B were then mixed under vigorous stirring. The previously obtained substrate was added to the mixed solution and stirred for 1 hour, followed by precipitation at 40 °C for 28 hours. The substrate was then removed, washed, and dried for 24 hours. Afterward, phosphating was performed in a tube furnace, with the substrate mass to sodium hypophosphite mass ratio being 1:20. Initially, the temperature was increased to 200 °C at a rate of 2 °C / min and held for 1 hour. Then, the temperature was increased to 300 °C at a rate of 5 °C / min and held for 2 hours. The final high-entropy metal phosphide, FeCoNiMnZnP, was obtained.

[0052] Example 2

[0053] At 25℃, weigh 0.404g of ferric nitrate nonahydrate (1mmol), 0.291g of nickel nitrate hexahydrate (1mmol), and 0.140g of hexamethylenetetrammonium (1mmol), dissolve them in 70mL of deionized water, and then place the solution in a hydrothermal reactor. Cut a 1cm section... -2Copper foam of various sizes was also placed in a hydrothermal reactor, with a heating rate of 1-20℃ / min, a reaction temperature of 60-120℃, and a reaction time of 10-25h. After the reaction, the substrate was removed, washed, and dried for 24h. 0.202g of ferric nitrate nonahydrate (0.5mmol), 0.291g of cobalt nitrate hexahydrate (1mmol), 0.238g of cobalt chloride hexahydrate (1mmol), 0.291g of nickel nitrate hexahydrate (1mmol), 0.119g of nickel chloride hexahydrate (0.5mmol), 0.266g of chromium chloride hexahydrate (1mmol), 0.121g of copper nitrate trihydrate (0.5mmol), and 0.882g of trisodium citrate dihydrate (3... Solution A was prepared by dissolving 0.329 g potassium ferricyanide (1 mmol) and 0.281 g sodium ferricyanide (1 mmol) in 100 mL of deionized water. Solutions A and B were mixed under vigorous stirring. The previously obtained substrate was then added to the mixed solution and stirred for 1 h. After precipitation at 50 °C for 30 h, the substrate was removed, washed, and dried for 24 h. The substrate was then calcined and phosphated in a tube furnace with a substrate mass ratio of 1:15 to sodium hypophosphite. The initial heating rate was 3 °C / min, reaching 220 °C and holding for 0 h. The subsequent heating rate was 5 °C / min, reaching 400 °C and holding for 3.5 h. The final high-entropy metal phosphide, FeCoNiCrCuP, was obtained.

[0054] Example 3

[0055] At 25℃, weigh 0.291g nickel nitrate hexahydrate (1mmol), 0.119g nickel chloride hexahydrate (0.5mmol), and 0.140g hexamethylenetetrammonium (1mmol), dissolve them in 70mL of deionized water, and then place the solution in a hydrothermal reactor. Cut a 1cm section... -2Carbon paper of various sizes was also placed in a hydrothermal reactor. The heating rate was 1-20℃ / min, the reaction temperature was 60-120℃, and the reaction time was 10-25h. After the reaction, the substrate was removed, washed, and dried for 24h. The following were weighed: 0.404g ferric nitrate nonahydrate (1mmol), 0.238g cobalt chloride hexahydrate (1mmol), 0.291g cobalt nitrate hexahydrate (1mmol), 0.291g nickel nitrate hexahydrate (1mmol), 0.119g nickel chloride hexahydrate (0.5mmol), 0.121g copper nitrate trihydrate (0.5mmol), 0.126g manganese nitrate tetrahydrate (0.5mmol), and 0.882g trisodium citrate dihydrate (3mg). Solution A was prepared by dissolving 0.329 g of potassium ferricyanide (1 mmol) and 0.281 g of sodium ferricyanide (1 mmol) in 100 mL of deionized water. Solutions A and B were mixed under vigorous stirring. The previously obtained substrate was then added to the mixed solution and stirred for 1 h. After precipitation at 20 °C for 30 h, the substrate was removed, washed, and dried for 24 h. The substrate was then calcined and phosphated in a tube furnace with a substrate mass ratio of 1:10 to sodium hypophosphite. The temperature was initially increased to 200 °C at a rate of 2 °C / min and held for 1 h. Then, the temperature was increased to 350 °C at a rate of 10 °C / min and held for 2.5 h. The final high-entropy metal phosphide, FeCoNiCuMnP, was obtained.

[0056] The present invention has been illustrated with the above embodiments to demonstrate its detailed features and methods. However, the present invention is not limited to the above-described detailed features and methods, meaning that the present invention does not necessarily depend on the above-described detailed features and methods for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the components used in the present invention, additions of auxiliary components, selection of specific methods, and other changes made within the scope of knowledge possessed by those skilled in the art, without departing from the spirit of the present invention, all fall within the protection and disclosure scope of the present invention.

[0057] Materials characterization and testing

[0058] Figure 1 Scanning electron microscope image of the high-entropy phosphide FeCoNiCuMnP prepared for Example 3, showing a morphology of nanoparticle aggregation;

[0059] Figure 2 The X-ray diffraction pattern of the high-entropy phosphide FeCoNiCuMnP prepared for Example 3 shows that it has a single-phase CoP structure and there is no phase separation.

[0060] Figure 3The OER linear sweep voltammetry of the high-entropy phosphide FeCoNiCuMnP prepared in Example 3 is shown in the figure at 50 mA cm⁻¹. -2 The overpotential at the current density is 266mV;

[0061] Figure 4 The Tafel slope plot of the OER of the high-entropy phosphide FeCoNiCuMnP prepared in Example 3 is shown, with a Tafel slope of 67 mV dec. -1 ;

[0062] Figure 5 The high-entropy phosphide FeCoNiCuMnP prepared for Example 3 was subjected to an ampere- ... -2 The results of a 40-hour chronopotential stability test at a given current density are shown in the figure. After 40 hours, the potential showed no significant change and remained stable.

Claims

1. A method of synthesizing a high-entropy metal phosphide catalytic material, the method comprising: The method comprises the following steps: ​ (1) selecting appropriate metal salt and alkali source and substrate, taking out after incubation at a certain temperature for a certain time, washing and drying for a certain time to obtain the substrate with growing metal hydroxide; the incubation at a certain temperature for a certain time comprises a heating rate of 1-20 ℃ / min, a reaction temperature of 80-180 ℃ and a reaction time of 10-48 h; (2) selecting appropriate metal salt solution and chelating agent, dissolving in aqueous solution to obtain solution A; (3) selecting appropriate ferricyanide and cobalt cyanide; dissolving in aqueous solution to obtain solution B; (4) slowly adding solution B to solution A under vigorous stirring; (5) placing the substrate with growing metal hydroxide in the mixed solution of step (4) and standing at a certain temperature for a certain time; (6) removing the solvent, taking out the substrate, washing thoroughly and drying to obtain the substrate with growing Prussian blue analogue; and centrifuging, washing and drying the precipitated substrate to obtain the Prussian blue analogue substrate; (7) placing the substrate and the phosphorus source in different positions of a tube furnace respectively, introducing protective gas, calcining at a certain temperature and incubating to obtain the final multi-metal phosphide grown on the substrate, i.e. high-entropy metal phosphide catalytic material, which has high catalytic activity and stability; the calcination in the tube furnace comprises: firstly, the heating rate is 0.5-5 ℃ / min, the temperature is raised to 150-250 ℃, and the incubation time is 0-1.5 h; then, the heating rate is 0.5-10 ℃ / min, the temperature is raised to 300-400 ℃, and the incubation time is 0.5-3.5 h.

2. The method of synthesizing high entropy metal phosphide catalytic material according to claim 1, wherein In step (1), the metal salt is a mixture of one or more of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric chloride hexahydrate, cobalt chloride hexahydrate and nickel chloride hexahydrate in any ratio, the alkali source is solid or liquid, the total molar amount of the metal salt added is 8:1-1:8 of the total molar amount of the alkali source added, and the water capacity is 60-80 mL; the selected substrate is nickel foam, copper foam, carbon cloth, carbon paper or stainless steel mesh.

3. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1 wherein In step (1), the washing process is 2-5 times of alternating cleaning with anhydrous ethanol and deionized water; the drying temperature is 60 ℃, and the drying time is 6-24 h.

4. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (2), the metal salt is a mixture of five or more than five metal salts containing different metal ions, such as ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, copper nitrate trihydrate, manganese nitrate tetrahydrate, chromium nitrate nonahydrate, zinc nitrate hexahydrate, ferric chloride hexahydrate, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate, manganese chloride tetrahydrate, chromium chloride hexahydrate and zinc chloride, in any ratio; the chelating agent is a mixture of one or more of trisodium citrate dihydrate, ethylenediaminetetraacetic acid and ethylenediamine; the molar ratio of the total amount of metal ions to the amount of the chelating agent added is 8:1-1:10; the water volume is 50-120 mL; the mixing temperature is 20-35 ℃; and the stirring time is 10-60 min to form solution A.

5. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (3), the solution B is a mixture solution of potassium ferricyanide, sodium ferricyanide or potassium cobalticyanide in any ratio, the molar ratio of the total moles of potassium ferricyanide, sodium ferricyanide or potassium cobalticyanide to the total moles of metal ions in the solution A is 2:1-1:6, the volume of water is 50-120 mL, the mixing temperature is 20-35℃, and the stirring time is 10-60 min.

6. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (4), the temperature for mixing the solutions A and B is 15-30℃, and the stirring time is 1-4 h.

7. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (5), the aging temperature is 15-45℃, and the precipitation time is 20-35 h.

8. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (6), the washing process is alternating washing with deionized water and anhydrous ethanol for 2-5 times; the drying temperature is 60℃, and the drying time is 6-24 h.

9. The method of synthesizing high entropy metal phosphide catalytic material as claimed in claim 1, wherein In step (7), sodium hypophosphite is selected as the phosphorus source; the mass ratio of the substrate to sodium hypophosphite is 1:1-1:20; and the protective gas is a mixture of nitrogen and argon in any ratio.

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