P-NiMoO4-Mish-Ni2P core-shell structure catalyst as well as preparation method and application of P-NiMoO4-Mish-Ni2P core-shell structure catalyst

Abstract

The invention discloses a P-NiMoO4 (at) Mish-Ni2P core-shell structure catalyst as well as a preparation method and application of the P-NiMoO4 (at) Mish-Ni2P core-shell structure catalyst. The preparation method of the catalyst comprises the following steps: step 1, cleaning the nickel substrate; step 2, synthesizing a precursor NiMoO4 on a nickel substrate through a hydrothermal method; step 3, the NiMoO4 is converted into a precursor NiMoO4 / Ni (OH) 2 through a secondary hydrothermal method; and step 4, carrying out phosphorization on the NiMoO4 / Ni (OH) 2 to prepare the catalyst with the P-NiMoO4 (at) Mish-Ni2P core-shell structure. The core of the catalyst is a phosphorus-doped NiMoO4 rod-shaped array, and the shell of the catalyst is a fishing net-shaped Ni2P layer. The catalyst shows excellent performance in hydrogen evolution reaction, has high activity and stability, and is suitable for production of clean hydrogen energy.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalysts, and in particular relates to a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst and a preparation method and application thereof. Background Art

[0002] Electrocatalytic water splitting technology is a promising method for clean hydrogen production, in which the hydrogen evolution reaction (HER) is the core process, which requires catalysts with high activity, excellent stability and economy. Although precious metal catalysts (such as Pt) perform well in HER, their high cost limits their possibility of large-scale application. Non-precious metal catalysts based on transition metals have become the focus of research due to their obvious advantages in reducing costs. Although various non-precious metal electrocatalysts have been proposed in recent years to improve the efficiency of water splitting, their performance is still far behind that of precious metal catalysts, especially in terms of electrocatalytic activity and long-term stability, which limits their promotion in practical applications. First, the structural design of many catalysts is insufficient, resulting in insufficient exposure of active sites, thereby limiting their catalytic activity. This structural deficiency prevents the catalyst from fully realizing its potential in practical applications. Secondly, the regulation of electronic structure is one of the key factors affecting catalytic performance. Many catalysts have slow HER kinetics due to the failure to effectively optimize the internal electronic structure. In addition, many powdered catalysts are currently connected to electrodes using binders, which reduces the conductivity of the catalyst and thus affects the electrochemical performance. The binder may decompose or fall off during long-term use, resulting in a reduction in the active area of ​​the catalyst, thereby reducing the catalytic efficiency. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst and its preparation method and application, aiming to solve the problems of insufficient active area, insufficient electronic structure regulation, poor conductivity and stability caused by the use of binders in the prior art. Through the present invention, the electrochemical activity, conductivity and long-term stability of the catalyst are significantly improved, showing excellent performance and long-term stability in the hydrogen evolution reaction.

[0004] To achieve the above object, the present invention provides a method for preparing a P-NiMoO4@ Mesh-Ni2P core-shell structure catalyst, comprising the following steps: Step 1. Nickel substrate treatment: Place the nickel substrate (2 cm × 5 cm) in 3M hydrochloric acid for ultrasonic cleaning for 5 minutes to remove the surface oxide layer and oil stains; then wash it alternately with ethanol and deionized water for 3 times, and finally dry it naturally at room temperature.

[0005] The purpose of this step is to provide a clean substrate for subsequent catalyst growth and ensure good adhesion and uniformity of the catalyst.

[0006] Step 2: Preparation of NiMoO4 precursor: nickel salt and ammonium molybdate ((NH4)6Mo7O 24 ·4H2O) was dissolved in 80mL of deionized water and stirred until the solution was clear. The solution was transferred to a 100mL Teflon-lined autoclave, and the nickel substrate treated in step 1 was placed vertically for hydrothermal reaction. After the reaction was completed, it was cooled to room temperature, and the nickel substrate loaded with yellow precipitate was taken out, washed with deionized water and ethanol in turn, and dried in an oven at 60 °C to obtain the precursor nickel molybdate (NiMoO4).

[0007] In this step, NiMoO4 with a rod-like array structure having a large specific surface area is formed on the nickel substrate through a hydrothermal reaction, which helps to increase the loading amount of subsequent active materials and serves as a fast channel for electron transfer in the hydrogen evolution reaction process.

[0008] Step 3, preparation of precursor NiMoO4 / Ni(OH)2: Dissolve nickel salt, ammonium fluoride (NH4F) and urea (CO(NH2)2) in 60 mL of deionized water and stir until the solution is clear. Immerse the nickel substrate loaded with NiMoO4 obtained in step 2 in the solution and transfer it to a 100 mL Teflon-lined autoclave for hydrothermal reaction. After the hydrothermal reaction is completed, cool to room temperature, take out the nickel substrate, wash it with deionized water and ethanol in turn, and dry it in an oven at 60 °C to obtain the precursor NiMoO4 / Ni(OH)2.

[0009] This step provides a precursor for the subsequent phosphating process by depositing Ni(OH)2 on the NiMoO4 rod arrays.

[0010] Step 4, preparation of P-NiMoO4@Mesh-Ni2P: The precursor NiMoO4 / Ni(OH)2 obtained in step 3 and sodium hypophosphite (Na2H2PO2·H2O) are placed in a tubular furnace and calcined under an argon atmosphere to finally form a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst.

[0011] Furthermore, the nickel salt used in step 1 may be one or more of nickel nitrate, nickel sulfate or nickel chloride.

[0012] Furthermore, the concentration of nickel ions in step 2 is 0.01-0.2 mol·L -1 , the molar ratio of nickel to molybdenum is 1:0.5~3.

[0013] Furthermore, in step 2, the temperature of the hydrothermal reaction is 100-160 °C, and the time is 4-14 h.

[0014] Furthermore, the concentration of nickel ions in step 3 is 0.01-0.1 mol·L -1 , the concentration of ammonium fluoride is 0.05~0.5mol·L -1 , the concentration of urea is 0.1~1.0mol·L -1 .

[0015] Furthermore, the temperature of the hydrothermal reaction in step 3 is 90-150 °C.

[0016] Furthermore, the hydrothermal reaction time in step 3 is 3 to 16 h. If the time is too short, the precursor NiMoO4 / Ni(OH)2 cannot be obtained; if the time is too long, the Ni(OH)2 coating layer is too thick, which hinders the exposure of the internal NiMoO4 structure.

[0017] Furthermore, the phosphating temperature of step 4 is 320-380 °C, the calcination time is 2-6 h, and the heating rate is 2-10 °C min -1 If the temperature is too low, the Ni(OH)2 in the precursor cannot be converted into nickel phosphide (Ni2P); if the temperature is too high, the Ni2P structure collapses.

[0018] Furthermore, in step 4, the ratio of the area of ​​the nickel substrate to the amount of sodium hypophosphite is 1 cm 2 : 0.05~2g.

[0019] On the other hand, the present invention also provides a P-NiMoO4@ Mesh-Ni2P core-shell structure catalyst prepared by the above method. The catalyst presents a unique core-shell structure, wherein the core is a phosphorus-doped nickel molybdate (P-NiMoO4) rod array structure, and the shell is a fishnet-like Ni2P layer (Mesh-Ni2P) coated on the top of P-NiMoO4. Among them, Mesh-Ni2P provides abundant active sites, while the inner core P-NiMoO4 provides a fast electron transfer channel. In addition, the core P-NiMoO4 and the shell Mesh-Ni2P interact with each other, regulate the electronic structure, optimize the adsorption energy of HER intermediates, and thus significantly improve the catalytic performance.

[0020] In another aspect, the present invention provides the use of a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst in a hydrogen evolution reaction.

[0021] The present invention has the following beneficial effects: (1) Structural optimization: The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst significantly improves the activity of hydrogen evolution reaction through the synergistic effect of the core and shell. The rod-shaped array structure increases the specific surface area and exposes more active sites.

[0022] (2) The catalyst prepared by the method of the present invention has a current density of 10 mA·cm -2 It exhibits a low hydrogen evolution overpotential of only 56 mV and can operate stably for 100 hours at this current density, demonstrating excellent stability.

[0023] (3) The binder-free self-supporting preparation method allows the catalyst to grow directly on the nickel substrate, thus having excellent conductivity and ensuring efficient electrocatalytic performance.

[0024] (4) The method of the present invention uses low-cost non-precious metal raw materials, significantly reduces the production cost of the catalyst, has good economic efficiency, and has the potential for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a scanning electron microscope image of the precursor NiMoO4 prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the precursor NiMoO4 / Ni(OH)2 prepared in Example 1 of the present invention; Figure 3 This is a scanning electron microscope image of P-NiMoO4@ Mesh-Ni2P prepared in Example 1 of the present invention; Figure 4 The X-ray powder diffraction pattern of P-NiMoO4@ Mesh-Ni2P prepared in Example 1 of the present invention; Figure 5 HER performance diagram of P-NiMoO4@ Mesh-Ni2P prepared in Example 1 of the present invention; Figure 6 This is a HER stability test diagram of P-NiMoO4@ Mesh-Ni2P prepared in Example 1 of the present invention; Figure 7 This is a comparison chart of the electroactive areas of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0030] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0031] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0032] Example 1 Step 1. Nickel substrate treatment: The nickel substrate (2 cm × 5 cm) was immersed in 3 M hydrochloric acid for ultrasonic cleaning for 5 minutes to remove the surface oxide layer and oil stains, and then washed alternately with ethanol and deionized water for 3 times, and finally dried naturally at room temperature.

[0033] Step 2: Preparation of NiMoO4 precursor: 0.8 mmol ammonium molybdate ((NH4)6Mo7O 24 ·4H2O) and 3.2 mmol nickel nitrate (Ni(NO3)2·6H2O) were dissolved in 80 mL of deionized water and stirred until the solution was clear. The concentration of nickel ions in the solution was 0.04 mol·L -1 , the molar ratio of nickel to molybdenum is 1:1.75. The solution was transferred to a 100 mL Teflon-lined autoclave, the nickel substrate treated in step 1 was placed vertically, and a hydrothermal reaction was performed at 150°C for 5 hours. After cooling to room temperature, it was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain the precursor NiMoO4.

[0034] Step 3: Preparation of NiMoO4 / Ni(OH)2 precursor: Dissolve 2 mmol nickel nitrate, 10 mmol ammonium fluoride (NH4F) and 20 mmol urea (CO(NH2)2) in 60 mL deionized water and stir until the solution is clear. The concentration of nickel ions in the solution is 0.033 mol·L -1 , the concentration of ammonium fluoride is 0.167 mol·L -1 , the concentration of urea is 0.333 mol·L -1 The NiMoO4-loaded nickel substrate obtained in step 2 was immersed in the solution and transferred to a 100 mL Teflon-lined autoclave for hydrothermal reaction at 120°C for 6 hours. After cooling to room temperature, it was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain the precursor NiMoO4 / Ni(OH)2.

[0035] Step 4, preparation of P-NiMoO4@Mesh-Ni2P: NiMoO4 / Ni(OH)2 obtained in step 3 was mixed with 1.0 g sodium hypophosphite (with a dosage ratio of 1 cm 2 :0.1 g) and placed in a tube furnace for phosphating treatment. The phosphating temperature was 350°C, the calcination time was 2 hours, and the heating rate was 5°C min -1 . The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst was obtained.

[0036] Example 2 Step 1. Nickel substrate treatment: The nickel substrate (2 cm × 5 cm) was immersed in 3 M hydrochloric acid for ultrasonic cleaning for 5 minutes to remove the surface oxide layer and oil stains, and then washed alternately with ethanol and deionized water for 3 times, and finally dried naturally at room temperature.

[0037] Step 2: Preparation of NiMoO4 precursor: 0.8 mmol ammonium molybdate ((NH4)6Mo7O 24 ·4H2O) and 3.2 mmol nickel nitrate (Ni(NO3)2·6H2O) were dissolved in 80 mL of deionized water and stirred until the solution was clear. The concentration of nickel ions in the solution was 0.04 mol·L -1 , the molar ratio of nickel to molybdenum is 1:1.75. The solution was transferred to a 100 mL Teflon-lined autoclave, the nickel substrate treated in step 1 was placed vertically, and a hydrothermal reaction was performed at 150°C for 5 hours. After cooling to room temperature, it was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain the precursor NiMoO4.

[0038] Step 3: Preparation of NiMoO4 / Ni(OH)2 precursor: Dissolve 1 mmol nickel nitrate, 5 mmol ammonium fluoride (NH4F) and 10 mmol urea (CO(NH2)2) in 60 mL deionized water and stir until the solution is clear. The concentration of nickel ions in the solution is 0.017 mol·L -1 , the concentration of ammonium fluoride is 0.085 mol·L -1 , the concentration of urea is 0.167 mol·L -1 The NiMoO4-loaded nickel substrate obtained in step 2 was immersed in the solution and transferred to a 100 mL Teflon-lined autoclave for hydrothermal reaction at 150°C for 4 hours. After cooling to room temperature, it was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain the precursor NiMoO4 / Ni(OH)2.

[0039] Step 4, preparation of P-NiMoO4@Mesh-Ni2P: NiMoO4 / Ni(OH)2 obtained in step 3 was mixed with 2.0 g sodium hypophosphite (with a dosage ratio of 1 cm 2 :0.2 g) and placed in a tube furnace for phosphating treatment. The phosphating temperature was 350°C, the calcination time was 2 hours, and the heating rate was 5°C min -1 . The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst was obtained.

[0040] Example 3 Step 1. Nickel substrate treatment: The nickel substrate (2 cm × 5 cm) was immersed in 3 M hydrochloric acid for ultrasonic cleaning for 5 minutes to remove the surface oxide layer and oil stains, and then washed alternately with ethanol and deionized water for 3 times, and finally dried naturally at room temperature.

[0041] Step 2: Preparation of NiMoO4 precursor: 0.6 mmol ammonium molybdate ((NH4)6Mo7O 24 ·4H2O) and 2.4 mmol nickel nitrate (Ni(NO3)2·6H2O) were dissolved in 80 mL of deionized water and stirred until the solution was clear. The concentration of nickel ions in the solution was 0.03 mol·L -1 , the molar ratio of nickel to molybdenum is 1:1.75. The solution was transferred to a 100 mL Teflon-lined autoclave, the nickel substrate treated in step 1 was placed vertically, and a hydrothermal reaction was performed at 120°C for 12 hours. After cooling to room temperature, the substrate was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain a NiMoO4 precursor.

[0042] Step 3: Preparation of NiMoO4 / Ni(OH)2 precursor: Dissolve 1 mmol nickel nitrate, 5 mmol ammonium fluoride (NH4F) and 10 mmol urea (CO(NH2)2) in 60 mL deionized water and stir until the solution is clear. The concentration of nickel ions in the solution is 0.017 mol L -1 , the concentration of ammonium fluoride is 0.085 mol·L -1 , the concentration of urea is 0.167 mol·L -1 The NiMoO4-loaded nickel substrate obtained in step 2 was immersed in the solution and transferred to a 100 mL Teflon-lined autoclave for hydrothermal reaction at 120°C for 12 hours. After cooling to room temperature, it was taken out, washed with deionized water and ethanol, and dried in an oven at 60°C to obtain the precursor NiMoO4 / Ni(OH)2.

[0043] Step 4, preparation of P-NiMoO4@Mesh-Ni2P: NiMoO4 / Ni(OH)2 obtained in step 3 was mixed with 1.0 g sodium hypophosphite (with a dosage ratio of 1 cm 2 :0.1 g) and placed in a tube furnace for phosphating treatment. The phosphating temperature was 350°C, the calcination time was 2 hours, and the heating rate was 5°C min -1 . The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst was obtained.

[0044] Physical characterization: The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst and its precursor obtained in Example 1 were physically characterized, and the results are as follows: Scanning electron microscope image of the precursor NiMoO4 ( Figure 1 ) shows a smooth micro / nanorod array structure; SEM image of the precursor NiMoO4 / Ni(OH)2 ( Figure 2 ) shows that Ni(OH)2 presents an interwoven nanosheet structure, coated on top of the NiMoO4 micro / nanorod array structure. SEM image of P-NiMoO4@Mesh-Ni2P ( Figure 3 ) exhibits a unique core-shell structure, in which the core is a phosphorus-doped nickel molybdate (P-NiMoO4) rod array structure; the shell is a fishnet-like Ni2P layer (Mesh-Ni2P) coated on the top of P-NiMoO4. The X-ray diffraction pattern shows ( Figure 4 ), the main components include Ni2P (PDF# 03-0953) and NiMoO4 (PDF#45-0142). During the phosphating process, P is also doped into the core NiMoO4.

[0045] Application in hydrogen evolution reaction: The activity and stability of the P-NiMoO4@Mesh-Ni2P catalyst prepared in Example 1 were tested for hydrogen evolution reaction.

[0046] (1) Activity test: The HER catalytic performance of P-NiMoO4@Mesh-Ni2P was evaluated in 1.0 M KOH solution using a standard three-electrode system. The polarization curves obtained by linear sweep voltammetry (LSV) ( Figure 5 ) showed that the catalyst only needed an overpotential of 49 mV to drive 10 mA cm in the hydrogen evolution reaction. -2 The current density of 10 mA·cm -2 At the current density, the overpotential is 267 mV, which indicates that the catalytic activity of the tested self-supporting electrode comes from the P-NiMoO4@Mesh-Ni2P catalyst supported on the surface of the nickel substrate.

[0047] (2) Stability test: at -100 mAcm -2 The catalyst worked stably for 100 hours at a current density of Figure 6 ).

[0048] Comparative Example 1 The difference from Example 1 is that in step 3, a bare nickel substrate is used instead of a nickel substrate loaded with precursor NiMoO4 for the second hydrothermal reaction, and the remaining steps remain the same, thereby preparing a catalyst with Ni2P grown on a nickel substrate.

[0049] The electrochemical activity test of Ni2P catalyst showed that in the hydrogen evolution reaction, to obtain 10 mA·cm -2 A current density of 176 mV overpotential is required ( Figure 5 ), which has a significantly lower activity than the P-NiMoO4@Mesh-Ni2P catalyst in Example 1 (49 mV).

[0050] Comparative Example 2 The difference from Example 1 is that the second hydrothermal reaction of step 3 is not performed. The nickel substrate loaded with NiMoO4 prepared in step 2 is directly used for phosphating to obtain a phosphorus-doped nickel molybdate catalyst (P-NiMoO4) grown on the nickel substrate.

[0051] The electrochemical activity test of P-NiMoO4 catalyst showed that at 10 mA·cm -2 When the hydrogen evolution reaction is carried out at a current density of , an overpotential of 201 mV is required ( Figure 5), which has a much lower activity than the P-NiMoO4@Mesh-Ni2P catalyst prepared in Example 1 (49 mV).

[0052] In addition, as Figure 7 As shown in the figure, compared with the catalysts of Comparative Examples 1 and 2, the P-NiMoO4@Mesh-Ni2P catalyst prepared in Example 1 has a lower Tafel slope (47.8 mV dec -1 )( Figure 7 a), indicating that it has faster hydrogen evolution reaction kinetics. At the same time, the catalyst also exhibits a larger active area (254.4 mF cm -2 )( Figure 7 b). These results indicate that the P-NiMoO4@Mesh-Ni2P core-shell structure is an electrocatalyst for hydrogen evolution reaction that exhibits excellent performance.

[0053] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst, characterized in that: The following steps are involved: Step 1, nickel substrate treatment: place the nickel substrate in 3M hydrochloric acid for ultrasonic cleaning for 5 minutes to remove the surface oxide layer and oil stains; then wash it alternately with ethanol and deionized water for 3 times and dry it at room temperature; Step 2, preparation of precursor NiMoO4: dissolve nickel salt and ammonium molybdate in 80 mL of deionized water, stir until the solution is clear, transfer the solution to a 100 mL Teflon-lined autoclave, place the nickel substrate treated in step 1 vertically, perform a hydrothermal reaction, cool to room temperature after the reaction, take out the nickel substrate, wash it with deionized water and ethanol, and dry it in an oven at 60°C to obtain the precursor NiMoO4; Step 3, preparation of precursor NiMoO4 / Ni(OH)2: dissolve nickel salt, ammonium fluoride and urea in 60 mL of deionized water, stir until the solution is clear, immerse the nickel substrate loaded with NiMoO4 obtained in step 2 in the solution, and transfer to a 100 mL Teflon-lined autoclave for hydrothermal reaction; after the reaction is completed, cool to room temperature, take out the nickel substrate, wash it with deionized water and ethanol in turn, and dry it in an oven at 60°C to obtain the precursor NiMoO4 / Ni(OH)2; Step 4: Preparation of P-NiMoO4@Mesh-Ni2P: The nickel substrate loaded with the precursor NiMoO4 / Ni(OH)2 in step 3 and sodium hypophosphite are simultaneously placed in a tubular furnace for phosphating treatment to obtain a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst.

2. The preparation method according to claim 1, characterized in that: The concentration of nickel salt in step 2 is 0.01~0.2mol·L -1 , the molar ratio of nickel to molybdenum is 1:0.5~3.

3. The preparation method according to claim 1, characterized in that: The hydrothermal reaction temperature in step 2 is 100-160°C and the reaction time is 4-14 h.

4. The preparation method according to claim 1, characterized in that: The concentration of nickel salt in step 3 is 0.01~0.1mol·L -1 , the concentration of ammonium fluoride is 0.05~0.5mol·L -1 , the concentration of urea is 0.1~1.0mol·L -1 .

5. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step 3 is 90-150°C and the time is 3-16 h.

6. The preparation method according to claim 1, characterized in that: The ratio of the area of ​​the nickel substrate to the amount of sodium hypophosphite in step 4 is 1 cm 2 : 0.05~2g.

7. The preparation method according to claim 1, characterized in that: The phosphating temperature in step 4 is 320-380 °C, the calcination time is 2-6 h, and the heating rate is 2-10 °C min -1 .

8. The P-NiMoO4@Mesh-Ni2P core-shell structure catalyst prepared according to claims 1 to 7, characterized in that The core is a phosphorus-doped nickel molybdate (P-NiMoO4) rod array structure, and the shell is a fishnet-like nickel phosphide layer (Mesh-Ni2P), which is coated on the top of the rod array structure.

9. Application of a P-NiMoO4@Mesh-Ni2P core-shell structure catalyst in hydrogen evolution reaction.

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