Three-dimensional structure NiCoP / CoMoO4 composite nanorods and their preparation method and application

Abstract

The present invention provides three-dimensional NiCoP / CoMoO4 composite nanorods, their preparation method, and applications. A cobalt source and a molybdenum source are first mixed in water, nickel foam is added, and a hydrothermal reaction is performed to produce cobalt molybdate. Alkaline etching and ion exchange are then performed to obtain NiCo(OH)2 / CoMoO4. This process is then followed by phosphating to produce NiCoP / CoMoO4. Compared to existing technologies, the three-dimensional NiCoP / CoMoO4 composite nanorods of the present invention possess large specific surface area and excellent electrical conductivity, making them suitable for use as high-performance hydrogen evolution electrocatalysts. Furthermore, the composite structure of nickel cobalt phosphide and cobalt molybdate enhances the electrical conductivity of the cobalt molybdate itself, thereby achieving higher catalytic efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterial technology and electrocatalysis, and specifically relates to three-dimensional NiCoP / CoMoO4 composite material nanorods and a preparation method and application thereof. Background Art

[0002] The world's growing energy demand has led to a worsening energy crisis. The energy structure, primarily fueled by fossil fuels, is no longer able to meet society's energy needs. Furthermore, climate change and environmental pollution caused by the severe consumption of fossil fuels have become critical challenges that must be addressed in society's development. Therefore, the search for clean energy is essential for the development of sustainable and renewable energy systems.

[0003] As an optimal energy carrier, hydrogen, with its high calorific value and pollution-free combustion products, can be used as a clean energy source to address energy challenges and reduce carbon emissions. Among them, "green hydrogen" produced from renewable energy is the most suitable hydrogen energy for clean energy conversion. Currently, the most ideal "green hydrogen" production strategy is water electrolysis based on electrocatalytic reactions. The process of producing hydrogen from water electrolysis involves two half-reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The efficiency of the catalyst is crucial for converting electrical energy into hydrogen.

[0004] Currently, commercial water electrolysis materials are still mainly based on precious metals such as Pt, Ir, Ru and their compounds. However, precious metals are scarce on Earth and are expensive, which is not conducive to large-scale promotion and utilization.

[0005] Therefore, in the face of the industrial demand for low cost and high efficiency, it is urgent to develop non-precious metal-based catalysts with excellent electrohydrolysis performance. Summary of the Invention

[0006] The present invention aims to provide three-dimensional NiCoP / CoMoO4 composite nanorods and a method for preparing the same. The method provides a three-dimensional NiCoP / CoMoO4 composite nanorod with a large surface area for catalytic reactions and high catalytic efficiency. Furthermore, the nanorods are inexpensive and have broad industrial application prospects.

[0007] Another object of the present invention is to provide the use of three-dimensional NiCoP / CoMoO4 composite nanorods as a highly efficient hydrogen evolution electrocatalyst. Compared to conventional cobalt molybdate materials, these nanorods exhibit significantly improved hydrogen evolution performance and electrical conductivity, thereby achieving highly efficient electrocatalytic performance.

[0008] The specific technical solutions of the present invention are as follows:

[0009] The preparation method of three-dimensional structure NiCoP / CoMoO4 composite material nanorods comprises the following steps:

[0010] 1) mixing a cobalt source and a molybdenum source in water, adding nickel foam, and performing a hydrothermal reaction to obtain cobalt molybdate;

[0011] 2) placing the product of step 1) in an alkaline solution and heating the solution to react to obtain Co(OH)2 / CoMoO4;

[0012] 3) placing the product of step 2) in a nickel source solution and allowing it to stand and soak to obtain NiCo(OH)2 / CoMoO4;

[0013] 4) Phosphating the product of step 3) to obtain NiCoP / CoMoO4.

[0014] In step 1), the nickel foam is pretreated before use to remove oxides and oil stains on the surface; the specific method is: the nickel foam is ultrasonically cleaned with 3M hydrochloric acid, anhydrous ethanol and deionized water in sequence.

[0015] In step 1), the molar ratio of the cobalt source to the molybdenum source is 2-2.5:1;

[0016] In step 1), the ratio of the cobalt source to water is 0.03-0.04 mol / L; the water is preferably deionized water;

[0017] In step 1), the cobalt source is selected from soluble cobalt salts, preferably cobalt nitrate hexahydrate;

[0018] In step 1), the molybdenum source is selected from a soluble molybdenum salt, preferably ammonium molybdate tetrahydrate;

[0019] In step 1), the cobalt source and the molybdenum source are mixed in water, subjected to ultrasonic treatment and then stirred; the ultrasonic treatment time is 10 minutes and the stirring time is 5 minutes;

[0020] In step 1), the hydrothermal reaction has a reaction temperature of 150° C. and a reaction time of 6 h.

[0021] In step 2), the alkali solution is a potassium hydroxide solution with a concentration of 1 mol / L;

[0022] The volume of the alkali solution in step 2) is the same as the volume of the water in step 1);

[0023] In step 2), the heating reaction has a reaction temperature of 120° C. and a reaction time of 5 h.

[0024] In step 2), potassium hydroxide is used to etch the surface of the substrate to form cobalt hydroxide, thereby obtaining Co(OH)2 / CoMoO4.

[0025] In step 3), the concentration of the nickel source solution is 0.1 mol / L, and the molar amount of nickel ions in the nickel source solution is 6-7 times the molar amount of the cobalt source in step 1);

[0026] In step 3), the nickel source is selected from a soluble nickel salt, preferably nickel nitrate;

[0027] In step 3), ion exchange is performed using a nickel source to obtain cobalt nickel hydroxide NiCo(OH)2 / CoMoO4;

[0028] In step 3), the soaking is allowed to stand for 1 hour;

[0029] In step 4), sodium hypophosphite is used for phosphation; the molar amount of the sodium hypophosphite is 4-12 times the molar amount of the cobalt source in step 1);

[0030] In step 4), the reaction atmosphere of the phosphating is high-purity nitrogen, the phosphating annealing temperature is 350-450° C., the phosphating annealing time is 2 h, the phosphating is carried out in a tube furnace, and the phosphating is carried out by vapor deposition method.

[0031] The three-dimensional NiCoP / CoMoO4 composite nanorods provided by the present invention are prepared by the above method. The NiCoP / CoMoO4 material is a three-dimensional rod-shaped structure supported on nickel foam, and mesopores are distributed on the three-dimensional rod-shaped structure, and the mesopore size is 2-5nm.

[0032] The application of the three-dimensional structure NiCoP / CoMoO4 composite nanorods provided by the present invention as a hydrogen evolution electrocatalyst, the product prepared by the present invention has a large specific surface area, good conductivity and durability, and can be used as an excellent hydrogen evolution electrocatalyst. -2 At a current density of 50 mA / cm, the overpotential of the in-situ grown NiCoP / CoMoO4 nanorod material on nickel foam is only 147 mV. -2 The hydrogen evolution was continued for 100 h at a current density of 1.5 %.

[0033] Compared to existing technologies, the method disclosed in this invention for preparing NiCoP / CoMoO4 nanorods by in-situ growth on nickel foam is simple, low-cost, mild, and environmentally friendly. First, cobalt molybdate nanorods are formed on a conductive nickel foam, and then cobalt nickel phosphide with a mesoporous structure is constructed on the surface of the cobalt molybdate. The resulting NiCoP / CoMoO4 material has a larger specific surface area than cobalt molybdate. Furthermore, the composite structure of cobalt nickel phosphide and cobalt molybdate enhances the conductivity of the cobalt molybdate itself, thereby achieving higher catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is a scanning electron microscope (SEM) image of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0035] Figure 2 This is a transmission electron microscope (TEM) image of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0036] Figure 3 The BET adsorption-desorption curve and pore size distribution of the NiCoP / CoMoO4 composite nanorod material in situ grown on nickel foam prepared in Example 1;

[0037] Figure 4 The X-ray diffraction spectrum (XRD) of the NiCoP / CoMoO4 composite nanorod material in situ grown on nickel foam prepared in Example 1;

[0038] Figure 5 This is a high-resolution transmission electron microscopy (HRTEM) image of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0039] Figure 6 Element mapping of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0040] Figure 7 The linear sweep cyclic voltammogram (LSV) of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0041] Figure 8 The cyclic voltammogram (CV) of the electrochemical double layer capacitance of the NiCoP / CoMoO4 composite nanorod material in situ grown on nickel foam prepared in Example 1;

[0042] Figure 9 This is a graph of the electrochemically active surface area (ECSA) of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0043] Figure 10 This is an electrochemical impedance spectroscopy (EIS) graph of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0044] Figure 11 This is a chronopotentiometry diagram of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam prepared in Example 1;

[0045] Figure 12 This is a comparison diagram of the linear sweep cyclic voltammetry (LSV) of the NiCoP / CoMoO4 composite nanorod material in situ grown on nickel foam prepared in Example 1 and the initial cobalt molybdate material. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0048] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0049] The nickel foam, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ammonium molybdate tetrahydrate, sodium hypophosphite, anhydrous ethanol and the like used in the present invention can be directly purchased from sales manufacturers in the market.

[0050] Example 1

[0051] The preparation method of three-dimensional structure NiCoP / CoMoO4 composite material nanorods comprises the following steps:

[0052] 1) Preparation of clean nickel foam:

[0053] Cut a 2cm x 3cm piece of nickel foam into a 50mL beaker. Add 50mL of 3M hydrochloric acid solution and sonicate for 15 minutes. Then, remove the hydrochloric acid. Add anhydrous ethanol and sonicate for 15 minutes. Finally, remove the anhydrous ethanol and rinse with deionized water and sonicate for 15 minutes. After sonication, remove the nickel foam and vacuum dry it at 60°C for 6 hours.

[0054] 2) Preparation of cobalt molybdate material loaded on nickel foam:

[0055] Weigh 305mg of cobalt nitrate hexahydrate and 556mg of ammonium molybdate tetrahydrate into a 50mL beaker, add 30mL of deionized water, and ultrasonicate for 10 minutes to accelerate the dissolution of the reagents, then stir for 5 minutes to evenly disperse the reagents. Pour the prepared solution into a 50mL polytetrafluoroethylene-lined stainless steel reactor and add a piece of clean nickel foam treated as above. The reactor was reacted in an oven at 150°C for 6 hours. After the reaction was completed and cooled to room temperature, the nickel foam in the reactor was removed and washed with deionized water and ethanol three times respectively, and vacuum dried at 60°C for 6 hours to obtain the cobalt molybdate material supported on the nickel foam. The surface of the obtained cobalt molybdate material was smooth and flat, and the material was relatively uniform.

[0056] 3) Preparation of Co(OH)2 / CoMoO4:

[0057] 1683 mg of potassium hydroxide was weighed into a 50 mL beaker and added to 30 mL of deionized water. The solution was ultrasonically treated for 10 minutes and then stirred for 5 minutes to obtain a 1 M potassium hydroxide solution. This solution was then transferred to a 50 mL Teflon-lined stainless steel reactor and the prepared material was added. The reactor was then heated in an oven at 120°C for 5 hours. After the reaction was complete and cooled to room temperature, the nickel foam was removed from the reactor and washed three times with deionized water and ethanol, respectively. The foam was then vacuum-dried at 60°C for 6 hours to obtain Co(OH)2 / CoMoO4. The surface of the material became rough, while the rod-like shape of the material was retained.

[0058] 4) Preparation of NiCo(OH)2 / CoMoO4:

[0059] 2.035g of nickel nitrate hexahydrate was weighed into a 100mL beaker, and 70mL of deionized water was added. After ultrasonic stirring, a 0.1M nickel nitrate solution was obtained. The prepared Co(OH)2 / CoMoO4 was immersed in the solution and allowed to stand for 1 hour. After the reaction was completed, the nickel foam was removed and washed three times with deionized water and ethanol, respectively. It was then vacuum-dried at 60°C for 6 hours to obtain NiCo(OH)2 / CoMoO4. The morphology of the material remained unchanged after the ion exchange.

[0060] 5) Weigh 0.4g of sodium hypophosphite into a porcelain boat and place it upstream of a tube furnace. Place the prepared NiCo(OH)2 / CoMoO4 in the downstream porcelain boat. Ramp the temperature at a rate of 5°C / min and anneal at 400°C under a nitrogen atmosphere for 2 hours. After the reaction is complete, remove the sample to obtain three-dimensional NiCoP / CoMoO4 composite nanorods. After phosphating, the material maintains a stable rod-like structure, and subsequent studies have confirmed that the surface nickel cobalt phosphide is mesoporous.

[0061] Characterization of three-dimensional NiCoP / CoMoO4 composite materials:

[0062] The morphology of the product obtained in Example 1 was analyzed using a scanning electron microscope (SEM). Figure 1 As shown, the prepared sample is a three-dimensional nanorod structure, and the surface of the rod appears to be very rough.

[0063] The morphology of the product obtained in Example 1 was analyzed using a transmission electron microscope (TEM). Figure 2 As shown, the prepared sample is a three-dimensional nanorod structure, and the surface of the rod is full of porous structures.

[0064] The pore analysis of the product obtained in Example 1 was performed using a specific surface and porosity analyzer. The results are as follows: Figure 3 As shown, the surface pores of the prepared sample are mesoporous structures with a pore size distribution of 2-5 nm.

[0065] The product obtained in Example 1 was detected by X-ray diffraction (XRD). Figure 4 The obtained spectrum is completely consistent with the NiCoP diffraction peak corresponding to JCPDS standard card No. 71-2336. This XRD pattern can well prove the successful formation of nickel cobalt phosphide on the surface of cobalt molybdate.

[0066] The product obtained in Example 1 was examined using a high-resolution transmission electron microscope (HRTEM). Figure 5 The lattice fringes correspond to the (-1 3 1) crystal plane of CoMoO4 and the (1 1 1) crystal plane of NiCoP, respectively, indicating the successful preparation of NiCoP / CoMoO4 composite materials.

[0067] The element mapping analysis of Example 1 was performed using a scanning electron microscope (SEM-Mapping). The results are as follows: Figure 6 The obtained spectrum shows that the elements Co, Ni, P, Mo, and O are evenly distributed in the nanorods. This mapping further proves that the material is a NiCoP / CoMoO4 composite material.

[0068] Example 2

[0069] The preparation method of three-dimensional structure NiCoP / CoMoO4 composite material nanorods comprises the following steps:

[0070] 1) Preparation of clean nickel foam: same as in Example 1;

[0071] 2) Preparation of cobalt molybdate material supported on nickel foam: same as in Example 1;

[0072] 3) Preparation of Co(OH)2 / CoMoO4: Same as Example 1;

[0073] 4) Preparation of NiCo(OH)2 / CoMoO4: Same as Example 1;

[0074] 5) Weigh 1.0 g of sodium hypophosphite into a porcelain boat and place it upstream of a tube furnace. Place the prepared NiCo(OH)2 / CoMoO4 in the downstream porcelain boat. Ramp the temperature at a rate of 5°C / min and anneal at 400°C under a nitrogen atmosphere for 2 h. After the reaction is complete, remove the sample to obtain three-dimensional NiCoP / CoMoO4 composite nanorods.

[0075] Example 3

[0076] The preparation method of three-dimensional structure NiCoP / CoMoO4 composite material nanorods comprises the following steps:

[0077] 1) Preparation of clean nickel foam: same as in Example 1;

[0078] 2) Preparation of cobalt molybdate material supported on nickel foam: same as in Example 1;

[0079] 3) Preparation of Co(OH)2 / CoMoO4: Same as Example 1;

[0080] 4) Preparation of NiCo(OH)2 / CoMoO4: Same as Example 1;

[0081] 5) Weigh 0.4 g of sodium hypophosphite into a porcelain boat and place it upstream of a tube furnace. Place the prepared NiCo(OH)2 / CoMoO4 in the downstream porcelain boat. Ramp the temperature at a rate of 5°C / min and anneal at 450°C under a nitrogen atmosphere for 2 h. After the reaction is complete, remove the sample to obtain three-dimensional NiCoP / CoMoO4 composite nanorods.

[0082] Example 4

[0083] The preparation method of three-dimensional structure NiCoP / CoMoO4 composite material nanorods comprises the following steps:

[0084] 1) Preparation of clean nickel foam: same as in Example 1;

[0085] 2) Preparation of cobalt molybdate material supported on nickel foam: same as in Example 1;

[0086] 3) Preparation of Co(OH)2 / CoMoO4: Same as Example 1;

[0087] 4) Preparation of NiCo(OH)2 / CoMoO4: Same as Example 1;

[0088] 5) Weigh 0.4 g of sodium hypophosphite into a porcelain boat and place it upstream of a tube furnace. Place the prepared NiCo(OH)2 / CoMoO4 in the downstream porcelain boat. Ramp the temperature at a rate of 5°C / min and anneal at 350°C for 2 h under a nitrogen atmosphere. After the reaction is complete, remove the sample to obtain three-dimensional NiCoP / CoMoO4 composite nanorods.

[0089] Application Example 1

[0090] Application of three-dimensional NiCoP / CoMoO4 composite nanorods as an electrode material for hydrogen evolution reaction. The details are as follows:

[0091] The instruments used in the following tests are all CHI660E electrochemical workstations, manufactured by Shanghai Chenhua Instrument Co., Ltd.

[0092] The following tests all adopted a three-electrode system, in which the nanorods of the three-dimensional structured NiCoP / CoMoO4 composite material prepared in Example 1 were used as the working electrode (1x1 cm); a graphite electrode was used as the counter electrode, an Ag / AgCl electrode was used as the reference electrode; and a 1 M KOH solution was used as the electrolyte.

[0093] (1) Linear sweep cyclic voltammetry (LSV) test

[0094] At 5mV s -1 The linear sweep cyclic voltammetry curve of the in-situ grown NiCoP / CoMoO4 composite material on nickel foam in Example 1 is as follows: Figure 7 As shown, the potential range of the curve is 0-0.3V (relative to standard hydrogen potential). From the LSV diagram, it can be seen that when the potential is in the range of 0.1-0.3V, the current density at the corresponding point of the curve increases sharply. -2 At a current density of 1.5 Å, the overpotential of the in-situ grown NiCoP / CoMoO4 nanorod material on nickel foam is only 147 mV. This phenomenon indicates that the prepared three-dimensional structure of the NiCoP / CoMoO4 composite nanorods has excellent electrocatalytic hydrogen evolution performance.

[0095] Among them, the calculation formula of electric potential is: E RHE / V=E Ag / AgCl +(0.059pH+0.197V); tested under IR compensation.

[0096] (2) Cyclic voltammetry (CV) test of electrochemical double layer capacitors

[0097] The CV graphs were measured at a scan rate of 20 mV s -1 , 40mV s -1 , 60mV s -1, 80mV s -1 The test voltage range is -0.98 to -0.88 V (relative to the silver / silver chloride electrode), which is not the electromagnetic effect of the Raday, and the cyclic voltammogram of the electrochemical double layer capacitor in Example 1 is obtained, as shown in FIG. Figure 8 shown.

[0098] (3) Electrochemically active surface area (ECSA) test

[0099] The figure is provided by Figure 8 The calculation formula of electrochemically active surface area is: ECSA / cm 2 =C dl / C s , where C dl is the electrochemical double layer capacitance, which is obtained from the relationship between capacitance current and scan rate; where C s Indicates specific electrochemical double layer capacitance (0.04mF cm -2 ). After calculation, draw the electrochemical active surface area diagram in Example 1. Figure 9 It can be seen that the electrochemical active surface area of ​​the NiCoP / CoMoO4 composite material grown in situ on nickel foam is 52.2 mF cm -2 , indicating that the material has a large electrochemically active surface area for hydrogen evolution reaction.

[0100] (4) Electrochemical impedance spectroscopy (EIS) test

[0101] The AC impedance spectrum of the NiCoP / CoMoO4 composite electrode grown in situ on nickel foam was obtained by electrochemical impedance spectroscopy, such as Figure 10 As shown in the figure. The intersection of the impedance spectrum and the real axis is the internal resistance of the NiCoP / CoMoO4 composite material grown in situ on nickel foam, which includes the resistance of the active material itself, the resistance of the electrolyte, and the contact resistance between the active material and the electrolyte. It can be seen that the NiCoP / CoMoO4 composite material grown in situ on nickel foam has a very small charge transfer resistance. This is due to the mesoporous structure constructed on the surface of the material, which provides abundant reaction sites for the catalytic reaction. This shows that the NiCoP / CoMoO4 composite material grown in situ on nickel foam can be used as an excellent electrocatalyst material for hydrogen evolution.

[0102] (5) Chronopotentiometry (CP) test

[0103] The hydrogen evolution stability diagram of the NiCoP / CoMoO4 composite electrode in situ grown on nickel foam was obtained by chronopotentiometry, as shown in Figure 11 As shown. At 50mA / cm -2At a current density of 1.5 wt %, the NiCoP / CoMoO4 composite material continuously and stably evolved hydrogen for 100 h, demonstrating the good stability of the NiCoP / CoMoO4 composite material.

[0104] Comparison of linear sweep cyclic voltammetry (LSV) of the in-situ grown NiCoP / CoMoO4 composite nanorod material on nickel foam and the original cobalt molybdate material prepared in Example 1. Compared to the original cobalt molybdate material, its hydrogen evolution performance and conductivity are greatly improved, thus achieving efficient electrocatalytic performance.

[0105] The above embodiments are described to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing three-dimensional NiCoP / CoMoO4 composite nanorods, characterized in that: The preparation method comprises the following steps: 1) mixing a cobalt source and a molybdenum source in water, adding nickel foam, and performing a hydrothermal reaction to obtain cobalt molybdate; 2) placing the product of step 1) in an alkaline solution and heating the solution to react to obtain Co(OH)2 / CoMoO4; 3) placing the product of step 2) in a nickel source solution and allowing it to stand and soak to obtain NiCo(OH)2 / CoMoO4; 4) Phosphating the product of step 3) to obtain three-dimensional NiCoP / CoMoO4 composite nanorods.

2. The preparation method according to claim 1, characterized in that In step 1), the molar ratio of the cobalt source to the molybdenum source is 2-2.5:

1.

3. The preparation method according to claim 1 or 2, characterized in that In step 1), the hydrothermal reaction has a reaction temperature of 150° C. and a reaction time of 6 h.

4. The preparation method according to claim 1, characterized in that In step 2), the alkali solution is a potassium hydroxide solution with a concentration of 1 mol / L; the volume of the alkali solution is the same as the volume of water in step 1).

5. The preparation method according to claim 1 or 4, characterized in that In step 2), the heating reaction has a reaction temperature of 120° C. and a reaction time of 5 h.

6. The preparation method according to claim 1, characterized in that In step 3), the molar amount of nickel ions in the nickel source solution is 6-7 times the molar amount of the cobalt source in step 1).

7. The preparation method according to claim 1, characterized in that In step 4), sodium hypophosphite is used for phosphation; the molar amount of the sodium hypophosphite is 4-12 times the molar amount of the cobalt source in step 1).

8. The preparation method according to claim 1 or 7, characterized in that In step 4), the phosphating reaction atmosphere is high-purity nitrogen, the temperature is 350-450° C., and the time is 2 hours.

9. A three-dimensional NiCoP / CoMoO4 composite nanorod prepared by the preparation method according to any one of claims 1 to 8.

10. An application of the three-dimensional NiCoP / CoMoO4 composite nanorods according to claim 9, characterized in that: Application of hydrogen evolution electrocatalysts.

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