Electrocatalyst, method for preparing the same, and use thereof

Abstract

The application discloses an electrocatalyst and a preparation method and application thereof, and belongs to the field of electrocatalysts. The electrocatalyst comprises a conductive substrate and an active component; the active component is loaded on the surface of the conductive substrate; the structural formula of the active component is CeFe-LDH@F-NiCoP; F-NiCoP is fluorine-doped nickel-cobalt phosphide, and CeFe-LDH is cerium-iron layered double hydroxide; the F-NiCoP in the active component is in-situ grown on the surface of the conductive substrate in the form of a two-dimensional nanosheet array, and the CeFe-LDH nanoparticles in the active component are grown on the surface of the F-NiCoP two-dimensional nanosheet to form a three-dimensional heterostructure of the active component. The three-dimensional heterostructure electrocatalyst prepared by the application has rich catalytic active sites and excellent oxygen evolution catalytic activity, and exhibits excellent durability under alkaline large-current conditions, which is of great significance to promoting the development of green and clean energy.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, and particularly relates to an electrocatalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a green energy source, is considered an ideal alternative to traditional fossil fuels due to its high energy density, high conversion efficiency, abundant sources, and clean, pollution-free characteristics. Electrocatalytic water splitting for hydrogen production is a promising method, offering a clean and pollution-free process capable of large-scale hydrogen production. The oxygen evolution reaction (OER), as a crucial half-reaction, is complex and kinetically sluggish, determining the overall efficiency of the electrocatalytic water splitting process. Currently, noble metal (Ir and Ru)-based catalysts possess excellent OER catalytic activity; however, the scarcity and high cost of noble metals hinder large-scale production and application. Therefore, developing low-cost, high-performance non-noble metal-based OER electrocatalysts is of great significance.

[0003] Although a series of non-noble metal-based oxygen evolution electrocatalysts have been reported in recent years, most of these catalysts can only drive the OER at relatively low current densities (≤250 mAcm⁻²), while industrial production often requires catalysts with current densities of 500 mAcm⁻². -2 Even 1000mA cm -2 The alkaline high-current oxygen evolution electrocatalyst can achieve high current density and operate stably for extended periods. Therefore, the development and design of alkaline high-current oxygen evolution electrocatalysts are of great significance for promoting the development of water electrolysis hydrogen production technology.

[0004] Currently, transition metal phosphides (TMPs) have attracted much attention due to their high Faradaic efficiency, good catalytic activity, and environmental friendliness. However, the poor performance and insufficient structural characteristics of single-metal TMPs limit their development. Metal-organic frameworks (MOFs) have also garnered significant interest in electrocatalysis due to their high specific surface area, large pore size, designable and tunable pore structure, and functionalizability. However, most MOFs exhibit low conductivity, making it difficult to achieve good catalytic performance in electrocatalytic water splitting for hydrogen production. Summary of the Invention

[0005] In view of this, the present invention provides an electrocatalyst, its preparation method and application, the main purpose of which is to solve the technical problems of low activity and poor electrocatalytic performance of electrocatalysts.

[0006] On one hand, the present invention provides an electrocatalyst comprising a conductive substrate and an active ingredient; the active ingredient is loaded on the surface of the conductive substrate;

[0007] The active ingredient has the structural formula CeFe-LDH@F-NiCoP;

[0008] wherein the F-NiCoP is fluorine-doped nickel cobalt phosphide, and the CeFe-LDH is cerium-iron layered double hydroxide;

[0009] The F-NiCoP in the active component is grown in the form of a two-dimensional nanosheet array on the surface of the conductive substrate, and the CeFe-LDH nanoparticles in the active component are grown on the surface of the F-NiCoP two-dimensional nanosheet to form a three-dimensional heterogeneous structure of the active component.

[0010] Optionally, the conductive substrate comprises a nickel substrate, a nickel-iron substrate, an iron substrate, or a stainless steel substrate.

[0011] In a second aspect, the present application provides a preparation method of the above-mentioned electrocatalyst, comprising the following steps:

[0012] S1: obtaining a conductive substrate loaded nickel cobalt metal-organic framework nanosheet precursor;

[0013] S2: the conductive substrate loaded nickel cobalt metal-organic framework nanosheet precursor in step S1 is phosphorized by calcination to obtain a conductive substrate loaded fluorine-doped nickel cobalt phosphide nanosheet, denoted as F-NiCoP;

[0014] S3: a cerium source and an iron source are deposited on the surface of the conductive substrate loaded fluorine-doped nickel cobalt phosphide nanosheet in step S2 by electrodeposition to obtain a cerium-iron layered double hydroxide, forming an electrocatalyst with a three-dimensional heterogeneous structure of the active component, denoted as CeFe-LDH@F-NiCoP.

[0015] Optionally, in step S1, the preparation method of the conductive substrate loaded nickel cobalt metal-organic framework nanosheet precursor comprises: raw materials including a cobalt source, a nickel source, an organic ligand, and a solvent, and a conductive substrate are heated to react I under a closed condition to obtain a nickel cobalt metal-organic framework nanosheet precursor grown on the conductive substrate.

[0016] Optionally, in step S1, the temperature of the heating reaction I is 100-120℃, and the time of the heating reaction I is 4-10h.

[0017] Optionally, the temperature of the heating reaction I is selected from any value or a range value between any two values selected from 100℃, 103℃, 105℃, 108℃, 110℃, 112℃, 115℃, 118℃, and 120℃; and the time of reaction I is any value or a range value between any two values selected from 4h, 5h, 6h, 7h, 8h, 9h, and 10h.

[0018] Optionally, in step S1, the molar ratio of the cobalt source, the nickel source, and the organic ligand is 0.15-0.45:0.15-0.45:0.1-0.3.

[0019] Optionally, in step S1, the cobalt source is selected from cobalt nitrate, cobalt acetate or cobalt chloride; the nickel source is selected from nickel nitrate, nickel acetate or nickel chloride; the organic ligand is selected from terephthalic acid and / or tetrafluoro terephthalic acid; and the solvent includes a mixed solution of N,N-dimethylformamide, ethanol and deionized water.

[0020] Optionally, the cobalt nitrate is cobalt nitrate hexahydrate, and the nickel nitrate is nickel nitrate hexahydrate.

[0021] Optionally, the heating reaction I is a solvothermal reaction, and the solvothermal reaction is performed in a reaction kettle; and the product after the heating reaction I is washed with an organic solvent and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor grown on a conductive substrate.

[0022] Optionally, in step S2, the preparation method of the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate includes: heating reaction II of the nickel-cobalt metal-organic framework nanosheet precursor loaded on the conductive substrate and a phosphate salt in an inert atmosphere in step S1 to obtain a fluorine-doped nickel-cobalt phosphide nanosheet F-NiCoP loaded on the conductive substrate.

[0023] Optionally, in step S2, the heating reaction II is performed at a temperature of 350-450℃ for 1.5-2.5h.

[0024] Optionally, the heating reaction II is performed at a temperature selected from any value or a range value between any two values in the group consisting of 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃ and 450℃; and the reaction II is performed for a time selected from any value or a range value between any two values in the group consisting of 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h and 2.5h.

[0025] In the present application, the nickel-cobalt metal-organic framework nanosheet precursor loaded on the conductive substrate is completely phosphatized.

[0026] Optionally, in step S2, the phosphate salt is selected from sodium hypophosphite.

[0027] Optionally, the sodium hypophosphite is sodium hypophosphite monohydrate; the Ar purity is 99.99999%; the phosphatization temperature is 400℃, the heating rate is 2℃ / min, and the holding time is 2h. -1

[0028] Optionally, the heating reaction II is a phosphatization reaction, and the phosphatization reaction is performed in a tube furnace.

[0029] ​Optionally, the inert atmosphere comprises an argon atmosphere.

[0030] Optionally, in step S3, the process of electrodeposition comprises: using a mixed solution of a cerium source and an iron source as an electrolyte, using the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate in step S2 as a working electrode, using a carbon rod as a counter electrode, and using silver / silver chloride as a reference electrode, and performing electrodeposition under a constant voltage condition to deposit a cerium-iron layered double hydroxide on the surface of the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate.

[0031] Optionally, in step S3, the molar ratio of the cerium source to the iron source is 0.4-1.0:0.6-1.0.

[0032] The amount of the cerium source and the iron source deposited on the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate in the present application can be controlled by the deposition time.

[0033] Optionally, the molar ratio of the cerium source to the iron source is selected from 0.5-1.0:0.6-1.0.

[0034] Optionally, the molar ratio of the cerium source to the iron source is selected from 0.5-0.8:0.6-0.8.

[0035] Optionally, in step S3, the molar concentration of the electrolyte is 1-2 mmol / L, the temperature of the electrodeposition is 20-30℃, the voltage of the electrodeposition is -0.8-1.5 V vs. Ag / AgCl, and the time of the electrodeposition is 200-400 s.

[0036] Optionally, the deposition time is any of 200 s, 250 s, 300 s, 350 s, 400 s, or a range value between any two of them.

[0037] Optionally, in step S3, the electrocatalyst is vacuum dried, the temperature of the drying is 60-100℃, and the time of the drying is 6-12 h.

[0038] The present application provides a preparation method of a three-dimensional heterostructure electrocatalyst for alkaline large-current oxygen evolution, comprising the following steps:

[0039] (1) weigh cobalt nitrate hexahydrate, nickel nitrate hexahydrate, terephthalic acid, and tetrafluoro terephthalic acid, and add them to a mixed solution of N,N-dimethylformamide, ethanol, and deionized water, and fully ultrasonically dissolve them to obtain a precursor solution;

[0040] (2) place the nickel foam in the solution prepared in step (1) and ultrasonically treat it;

[0041] (3) the solution and the foamed nickel obtained in step (2) are transferred into a reaction kettle, sealed, and reacted at 100-120 DEG C for 4-10 h, and after the reaction is completed, the reaction kettle is naturally cooled to room temperature, washed with N,N-dimethylformamide and methanol, and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor grown on the foamed nickel;

[0042] (4) the nickel-cobalt metal-organic framework precursor obtained in step (3) and sodium hypophosphite are respectively placed in porcelain boats and placed in the downstream and upstream of the quartz tube of a tube furnace, heated to the phosphating reaction temperature under an Ar atmosphere, and kept at the temperature to perform phosphating, to obtain fluorine-doped nickel-cobalt phosphide nanosheets (F-NiCoP);

[0043] (5) cerium nitrate hexahydrate and iron nitrate nonahydrate are dissolved in deionized water, and an electrodeposition solution is obtained by ultrasonic treatment, the F-NiCoP obtained in step (4) is immersed in the prepared electrodeposition solution, and electrodeposition is performed under a constant voltage for a certain time, and the obtained product is washed with deionized water and vacuum dried to obtain a CeFe-LDH@F-NiCoP three-dimensional heterostructure electrocatalyst.

[0044] The three-dimensional heterostructure electrocatalyst for alkaline large-current oxygen evolution provided by the application is prepared by using foamed nickel as a substrate material, synthesizing a nickel-cobalt metal-organic framework nanosheet precursor with nickel and cobalt as metal centers and terephthalic acid and tetrafluoroterephthalic acid as organic ligands by a solvothermal method, phosphating the precursor in a tube furnace to obtain fluorine-doped nickel-cobalt phosphide nanosheets, and finally performing electrodeposition of cerium-iron layered double hydroxide on the fluorine-doped nickel-cobalt phosphide nanosheets by using a three-electrode electrochemical workstation, iron nitrate nonahydrate and cerium nitrate hexahydrate as an electrolyte, the fluorine-doped nickel-cobalt phosphide nanosheets as a working electrode, a carbon rod as a counter electrode, and silver / silver chloride as a reference electrode.

[0045] In a third aspect, the application provides an electrode material, which comprises the above-mentioned electrocatalyst.

[0046] In a fourth aspect, the application provides use of the above-mentioned electrocatalyst in alkaline large-current electrocatalytic oxygen evolution.

[0047] The three-dimensional heterostructure electrocatalyst prepared according to the design idea of the alkaline large-current oxygen evolution electrocatalyst provided by the application has abundant catalytic active sites and excellent oxygen evolution catalytic activity, and exhibits excellent durability under alkaline large-current conditions, which is of great significance for promoting the development of green and clean energy.

[0048] In a fifth aspect, the present application provides a standard three-electrode system, wherein the above-mentioned electrocatalytic material CeFe-LDH@F-NiCoP is used as a working electrode, Hg / HgO is used as a reference electrode, and a carbon rod is used as a counter electrode.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] (1) The present application provides a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) in-situ grown on the surface of foamed nickel for alkaline large-current oxygen evolution and a preparation method thereof.

[0051] (2) The foamed nickel provided by the present application has a three-dimensional porous structure and excellent electrical conductivity, and can be directly used as a working electrode when used as a base material to prepare an electrocatalyst, thereby effectively improving the catalytic activity and stability of the material.

[0052] (3) The F-NiCoP provided by the present application is in-situ grown on the surface of foamed nickel in the form of a two-dimensional nanosheet array, and can expose abundant catalytically active sites in combination with the surface-deposited CeFe-LDH, thereby ensuring full contact between the electrocatalyst and the electrolyte, reducing the internal resistance of the electrocatalyst, and ensuring high catalytic activity and stability of the electrocatalyst.

[0053] (4) The preparation method provided by the present application is simple, easy to implement, low in cost, and has high controllability, is conducive to large-scale production, and has a broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 A preparation flowchart of the CeFe-LDH@F-NiCoP prepared in Example 1 of the present application is shown in the figure;

[0055] Figure 2 A scanning electron microscope image of the CeFe-LDH@F-NiCoP prepared in Example 1 of the present application is shown in the figure;

[0056] Figure 3 A linear sweep voltammetry curve of the electrocatalytic oxygen evolution of the CeFe-LDH@F-NiCoP prepared in Example 1 of the present application is shown in the figure, and the electrolyte is 1.0M KOH aqueous solution;

[0057] Figure 4 A Tafel slope curve of the CeFe-LDH@F-NiCoP prepared in Example 1 of the present application is shown in the figure;

[0058] Figure 5 A stability test graph of the CeFe-LDH@F-NiCoP prepared in Example 1 of the present application at a current density of 1Acm -2 DETAILED DESCRIPTION

[0059] ​The application will be further described in conjunction with specific examples. The following description is merely some embodiments of the application, and does not limit the application in any form. Although the preferred embodiments are disclosed as follows, the application is not limited thereto, and any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the technical solutions of the application, which are equivalent to the equivalent embodiments and fall within the scope of the technical solutions.

[0060] Unless otherwise specified, the raw materials in the examples of the application are purchased through commercial channels and directly used without any special treatment.

[0061] Unless otherwise specified, the analysis methods in the examples all use the conventional settings of instruments or equipment and conventional analysis methods.

[0062] The analysis methods in the embodiments of the application are as follows:

[0063] The test method of the scanning electron microscope image is as follows: the sample is tested by using a scanning electron microscope (model: Quanta 200F).

[0064] The test method of the electrocatalytic oxygen evolution is as follows: the sample is tested by using an electrochemical workstation (model: CHI1140D).

[0065] In the application, mM means mmol / L.

[0066] Example 1

[0067] The three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) is prepared according to the method as shown in Figure 1 The steps are as follows:

[0068] (1) 87.3 mg of cobalt nitrate hexahydrate, 29.1 mg of nickel nitrate hexahydrate, 58.1 mg of terephthalic acid and 11.9 mg of tetrafluoroterephthalic acid are added to a mixed solution of 10 mL of N,N-dimethylformamide, 2 mL of ethanol and 1 mL of deionized water, and ultrasonic treatment is performed for 20 min; then it is transferred to a 20 mL polytetrafluoroethylene reaction kettle and treated foam nickel is added, and solvent thermal reaction is performed at 120℃ for 6 h; after the reaction kettle is naturally cooled to room temperature, it is washed with N,N-dimethylformamide and methanol, and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor (F-NiCo-MOF).

[0069] (2) The F-NiCo-MOF obtained in step (1) and sodium hypophosphite are respectively placed in porcelain boats and placed downstream and upstream of the quartz tube in a tube furnace. Then, under an Ar atmosphere, the temperature is increased at a rate of 2℃ / min to 300℃ and maintained for 2 h, and then the temperature is increased at a rate of 2℃ / min to 400℃ and maintained for 2 h. After the reaction is completed, the sample is naturally cooled to room temperature, and then the F-NiCoP is obtained by washing with deionized water and vacuum drying. -1The temperature of the tube furnace was raised to 400℃ at a rate of 5℃ / min, and the temperature was kept for 2h to obtain F-NiCoP nanosheets derived from F-NiCo-MOF.

[0070] (3) The F-NiCoP nanosheets obtained in step (2) were used as the working electrode, and a solution containing 0.6mM iron nitrate nine hydrate and 0.5mM cerium nitrate six hydrate was used as the electrodeposition solution, Ag / AgCl was used as the reference electrode, and a carbon rod was used as the counter electrode. The electrodeposition temperature was 25℃, the constant voltage was-1.0V vs. Ag / AgCl, and the electrodeposition time was 300s to prepare a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP).

[0071] The F-NiCoP nanosheets were prepared by the following steps: Figure 2 As can be seen, the F-NiCoP two-dimensional nanosheets grow neatly on the nickel foam base material, have uniform size, are well dispersed, and have many CeFe-LDH nanoparticles growing on the surface of the two-dimensional nanosheets, which can be seen as a successful formation of a heterostructure.

[0072] The three-dimensional heterostructure electrocatalyst CeFe-LDH@F-NiCoP prepared in Example 1 was subjected to electrocatalytic oxygen evolution performance test using 1.0M KOH aqueous solution, and the test process was as follows:

[0073] A Shanghai Chenhua CHI1140D workstation was used, a standard three-electrode system was adopted, CeFe-LDH@F-NiCoP was used as the working electrode, Hg / HgO was used as the reference electrode, and a carbon rod was used as the counter electrode. The linear sweep voltammetry curve of the electrocatalyst was tested at a scan rate of 5mV s -1 -1.0V in a potential range of 0.2-1.0V, and the corresponding Tafel slope curve was obtained from the linear sweep voltammetry curve. In addition, the current density of CeFe-LDH@F-NiCoP was set to be constant at 1000mA cm -2 -2, and the change of the potential of CeFe-LDH@F-NiCoP during the catalytic oxygen evolution was recorded to determine the stability of CeFe-LDH@F-NiCoP in the process of electrocatalytic oxygen evolution.

[0074] The test results are shown in Figure 3 , 4 and 5; Figure 3 The linear sweep voltammetry curve of CeFe-LDH@F-NiCoP in an alkaline solution is shown, and CeFe-LDH@F-NiCoP has an overpotential as low as 271 and 302mV at a current density of 500 and 1000mA cm -2 respectively.

[0075] Figure 4 The corresponding Tafel slope curve of CeFe-LDH@F-NiCoP is shown, and the value is 90.8mV dec-1 , indicating that it has good reaction kinetics.

[0076] Figure 5 CeFe-LDH@F-NiCoP has excellent long-term stability under 90h working conditions.

[0077] Example 2

[0078] This example prepares a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) according to the method shown in Figure 1 , and the steps are as follows:

[0079] (1) 101.9 mg of cobalt nitrate hexahydrate, 14.5 mg of nickel nitrate hexahydrate, 49.8 mg of terephthalic acid, and 20.8 mg of tetrafluoroterephthalic acid were added to a mixed solution of 10 mL of N,N-dimethylformamide, 2 mL of ethanol, and 1 mL of deionized water, ultrasonically treated for 20 min, then transferred to a 20 mL polytetrafluoroethylene reactor and added to the treated nickel foam, and solvent thermal reaction was carried out at 120℃ for 6h; after the reactor was naturally cooled to room temperature, it was washed with N,N-dimethylformamide and methanol, and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor (F-NiCo-MOF).

[0080] (2) The F-NiCo-MOF obtained in step (1) and sodium hypophosphite were placed in porcelain boats, respectively, downstream and upstream of the quartz tube in the tube furnace. Then the tube furnace was heated to 400℃ at a heating rate of 2℃ / min under Ar atmosphere, and kept for 2h to obtain F-NiCoP nanosheets derived from F-NiCo-MOF. -1

[0081] (3) The F-NiCoP nanosheets obtained in step (2) were used as the working electrode, 0.5mM of ferric nitrate nonahydrate and 0.6mM of cerium nitrate hexahydrate were used as the electrodeposition solution, Ag / AgCl was used as the reference electrode, and a carbon rod was used as the counter electrode. The electrodeposition temperature was 25℃, the constant voltage condition was -1.2V vs. Ag / AgCl, and the electrodeposition time was 240s. A three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) was prepared.

[0082] The electrocatalytic oxygen evolution performance test method is the same as in Example 1.

[0083] Example 3

[0084] This example prepares a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) according to the method shown in Figure 1 , and the steps are as follows:

[0085] ​(1) 58.2 mg of cobalt nitrate hexahydrate, 58.2 mg of nickel nitrate hexahydrate, 33.2 mg of terephthalic acid and 41.6 mg of tetrafluoroterephthalic acid were added into a mixed solution of 10 mL of N,N-dimethylformamide, 2 mL of ethanol and 1 mL of deionized water, ultrasonically treated for 20 min, then transferred into a 20 mL polytetrafluoroethylene reaction kettle and added with treated nickel foam, and subjected to solvothermal reaction at 120 °C for 6 h; after the reaction kettle was naturally cooled to room temperature, washed with N,N-dimethylformamide and methanol, and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor (F-NiCo-MOF).

[0086] (2) The F-NiCo-MOF obtained in step (1) and sodium hypophosphite were respectively placed in porcelain boats at the downstream and upstream of the quartz tube of a tube furnace. Then the tube furnace was heated to 400 °C at a temperature increasing rate of 2 °C / min under Ar atmosphere, and kept for 2 h to obtain F-NiCoP nanosheets derived from F-NiCo-MOF. -1

[0087] (3) The F-NiCoP nanosheets obtained in step (2) were used as a working electrode, a solution containing 0.4 mM of ferric nitrate nonahydrate and 0.7 mM of cerium nitrate hexahydrate was used as an electrodeposition solution, Ag / AgCl was used as a reference electrode, a carbon rod was used as a counter electrode, the electrodeposition temperature was 25 °C, the constant voltage condition voltage was -0.9 V vs. Ag / AgCl, and the electrodeposition time was 360 s to prepare a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP).

[0088] The electrocatalytic oxygen evolution performance test method was the same as in Example 1.

[0089] Example 4

[0090] This example prepared a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP) according to the method shown in Figure 1 , and the steps were as follows:

[0091] (1) 77.6 mg of cobalt nitrate hexahydrate, 38.8 mg of nickel nitrate hexahydrate, 41.5 mg of terephthalic acid and 31.2 mg of tetrafluoroterephthalic acid were added into a mixed solution of 10 mL of N,N-dimethylformamide, 2 mL of ethanol and 1 mL of deionized water, ultrasonically treated for 20 min, then transferred into a 20 mL polytetrafluoroethylene reaction kettle and added with treated nickel foam, and subjected to solvothermal reaction at 120 °C for 6 h; after the reaction kettle was naturally cooled to room temperature, washed with N,N-dimethylformamide and methanol, and vacuum dried to obtain a nickel-cobalt metal-organic framework nanosheet precursor (F-NiCo-MOF).

[0092] ​(2) The F-NiCo-MOF and sodium hypophosphite obtained in step (1) were respectively placed in a porcelain boat and placed downstream and upstream of the quartz tube in the tube furnace. Then the tube furnace was heated to 400℃ at a heating rate of 2℃ min -1 under Ar atmosphere and kept for 2h, obtaining F-NiCoP nanosheets derived from F-NiCo-MOF.

[0093] (3) The F-NiCoP nanosheets obtained in step (2) were used as the working electrode, 0.8mM iron nitrate nonahydrate and 0.4mM cerium nitrate hexahydrate were used as the electrodeposition solution, Ag / AgCl was used as the reference electrode, and a carbon rod was used as the counter electrode. The electrodeposition temperature was 25℃, the constant voltage condition voltage was-0.9V vs.Ag / AgCl, and the electrodeposition time was 360s, to prepare a three-dimensional heterostructure electrocatalyst (CeFe-LDH@F-NiCoP).

[0094] The electrocatalytic oxygen evolution performance test method was the same as in Example 1.

[0095] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed as above, they are not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. An electrocatalyst characterized in that, The electrocatalyst comprises an electrically conductive substrate and an active component; the active component is loaded on the surface of the electrically conductive substrate; the electrically conductive substrate is foamed nickel; The structural formula of the active component is CeFe-LDH@F-NiCoP; Wherein, the F-NiCoP is fluorine-doped nickel-cobalt phosphide, and the CeFe-LDH is cerium-iron layered double hydroxide; The F-NiCoP in the active component grows in the form of two-dimensional nanosheet array on the surface of the electrically conductive substrate in situ, and the CeFe-LDH nanoparticles in the active component grow on the surface of the F-NiCoP two-dimensional nanosheet to form a three-dimensional heterostructure of the active component; The preparation method of the electrocatalyst comprises the following steps: S1: Obtain an electrically conductive substrate loaded nickel-cobalt metal-organic framework nanosheet precursor: under airtight conditions, raw materials containing a cobalt source, a nickel source, an organic ligand and a solvent are heated to react I with an electrically conductive substrate to obtain a nickel-cobalt metal-organic framework nanosheet precursor grown on the electrically conductive substrate; The organic ligand is selected from terephthalic acid and tetrafluoroterephthalic acid; S2: The electrically conductive substrate loaded nickel-cobalt metal-organic framework nanosheet precursor in step S1 is phosphatized by calcination to obtain an electrically conductive substrate loaded fluorine-doped nickel-cobalt phosphide nanosheet, denoted as F-NiCoP; S3: A cerium source and an iron source are deposited on the surface of the electrically conductive substrate loaded fluorine-doped nickel-cobalt phosphide nanosheet in step S2 by electrodeposition to obtain a cerium-iron layered double hydroxide, forming an electrocatalyst with a three-dimensional heterostructure of the active component, denoted as CeFe-LDH@F-NiCoP.

2. A method of preparing an electrocatalyst as claimed in claim 1, characterized in that, Comprise the following steps: S1: Obtain an electrically conductive substrate loaded nickel-cobalt metal-organic framework nanosheet precursor: under airtight conditions, raw materials containing a cobalt source, a nickel source, an organic ligand and a solvent are heated to react I with an electrically conductive substrate to obtain a nickel-cobalt metal-organic framework nanosheet precursor grown on the electrically conductive substrate; The organic ligand is selected from terephthalic acid and tetrafluoroterephthalic acid; S2: The electrically conductive substrate loaded nickel-cobalt metal-organic framework nanosheet precursor in step S1 is phosphatized by calcination to obtain an electrically conductive substrate loaded fluorine-doped nickel-cobalt phosphide nanosheet, denoted as F-NiCoP; S3: A cerium source and an iron source are deposited on the surface of the electrically conductive substrate loaded fluorine-doped nickel-cobalt phosphide nanosheet in step S2 by electrodeposition to obtain a cerium-iron layered double hydroxide, forming an electrocatalyst with a three-dimensional heterostructure of the active component, denoted as CeFe-LDH@F-NiCoP.

3. The preparation method according to claim 2, characterized in that, In step S1, the heating reaction I has a temperature of 100 ~ 120°C, and a time of 4 ~ 10 h.

4. The production method according to claim 2, characterized by, In step S1, the molar ratio of the cobalt source, the nickel source and the organic ligand is 0.15 ~ 0.45: 0.15 ~ 0.45: 0.1 ~ 0.

3.

5. The preparation method according to claim 2, characterized in that, In step S1, the cobalt source is selected from cobalt nitrate, cobalt acetate or cobalt chloride; the nickel source is selected from nickel nitrate, nickel acetate or nickel chloride; and the solvent comprises a mixed solution of N,N-dimethylformamide, ethanol and deionized water.

6. The preparation method according to claim 2, characterized in that, The preparation method of the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate in step S2 comprises: heating reaction II of the nickel-cobalt metal-organic framework nanosheet precursor and the phosphate loaded on the conductive substrate in step S1 in an inert atmosphere to obtain the fluorine-doped nickel-cobalt phosphide nanosheet F-NiCoP loaded on the conductive substrate.

7. The production method according to claim 6, wherein In step S2, the heating reaction II is performed at a temperature of 350-450°C for 1.5-2.5h.

8. The preparation method according to claim 6, characterized in that, In step S2, the phosphate is selected from sodium hypophosphite.

9. The method of claim 2, wherein, In step S3, the process of the electrodeposition comprises: using a mixed solution of a cerium source and an iron source as an electrolyte, using the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate in step S2 as a working electrode, using a carbon rod as a counter electrode, and using silver / silver chloride as a reference electrode, and performing electrodeposition under a constant voltage condition to deposit a cerium-iron layered double hydroxide on the surface of the fluorine-doped nickel-cobalt phosphide nanosheet loaded on the conductive substrate.

10. The method of claim 2, wherein, In step S3, the molar ratio of the cerium source to the iron source is 0.4-1.0:0.6-1.

0.

11. The preparation method according to claim 9, characterized in that, In step S3, the electrodeposition is performed at a temperature of 20-30°C, a voltage of -0.8-1.5 V vs. Ag / AgCl, and for a time of 200-400s.

12. The method of claim 2, wherein, In step S3, the electrocatalyst is dried in vacuum at a temperature of 60-100°C for a time of 6-12h.

13. An electrode material, characterized by The electrode material comprises the electrocatalyst of claim 1.

14. Use of the electrocatalyst of claim 1 in alkaline high-current electrocatalytic oxygen evolution.

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