Molybdenum-nickel alloy-nickel oxide self-supporting catalyst and preparation method and application thereof

Abstract

The invention discloses a molybdenum-nickel alloy-nickel oxide self-supporting catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: adding a nickel metal substrate into a mixed solution containing Mo salt and urea to carry out solvothermal reaction, dissolving out a nickel matrix to provide a Ni source and react with Mo salt, and growing nano petals consisting of molybdenum-nickel oxide nanosheets in situ on the nickel matrix. And placing the precursor in a reducing atmosphere, and carrying out a heat preservation reaction to obtain the molybdenum-nickel alloy-nickel oxide self-supporting composite hydrogen evolution catalyst. The self-supporting structure does not need to be added with a binder, so that the large-current cycling stability of the catalyst is improved, the dispersion degree of MoNi4 alloy particles on the surface of a NiO nanosheet matrix is greatly increased through an in-situ precipitation mode, the conductivity of the catalyst is improved, a high-surface-area and rich high-activity MoNi4-NiO composite interface is obtained, and the high-current cycling stability of the catalyst is improved. Meanwhile, the hydrogen adsorption energy of the MoNi4 alloy surface and the water dissociation activity of the NiO surface are optimized through the strong electron coupling effect of the heterogeneous interface, and the alkaline hydrogen evolution activity of the composite catalyst is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional material preparation, and particularly relates to a molybdenum-nickel alloy-nickel oxide self-supporting catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen production by alkaline hydrogen evolution reaction is an industrial technology applicable to large-scale production of green hydrogen. Compared with acidic hydrogen evolution reaction, the biggest challenge of alkaline hydrogen evolution reaction lies in the need for an additional water dissociation step to break the strong H-OH covalent bond to generate adsorbed hydrogen intermediates for hydrogen conversion. In an alkaline medium, the high activation energy barrier of water dissociation makes the hydrogen evolution reaction very slow, so an efficient catalyst is needed to reduce the dissociation barrier of water and accelerate the alkaline HER process. Relevant research shows that the Ni sites of transition metal nickel oxide (NiO) can be used as efficient water adsorption and water dissociation sites due to the incomplete filling of its d orbitals, and it is a very promising alkaline hydrogen evolution catalyst. However, its inappropriate hydrogen adsorption energy results in a large gap between its alkaline hydrogen evolution performance and noble metals.

[0003] In contrast, alloying another transition metal element Mo with Ni to form a molybdenum-nickel alloy can significantly regulate the d-orbital electron structure of Ni metal by generating a 3d electron coupling effect, greatly enhancing the hydrogen desorption process. However, during the electrochemical test of a single molybdenum-nickel alloy, the breakdown potential of the molybdenum-nickel alloy is relatively low, which leads to the relatively unstable and easy dissolution of Mo element in application, resulting in the overall instability of the catalyst. Constructing a heterojunction can effectively improve the stability of the molybdenum-nickel alloy catalyst. For example, patent CN202410430064.9 discloses a self-supporting MoNi 4 / Mo 2 C heterojunction hydrogen evolution catalyst and a preparation method thereof, and a stable self-supporting MoNi 4 / Mo 2 C composite catalyst is obtained by laser treating the molybdenum-nickel powder coated on the surface of a nickel mesh. However, both the MoNi 4 phase and the Mo 2 C phase have relatively low water dissociation activity, resulting in insufficient catalytic efficiency. Therefore, it is very necessary to construct a heterojunction catalyst with higher catalytic efficiency. Summary of the Invention

[0004] The main purpose of the present invention is to provide a molybdenum-nickel alloy-nickel oxide self-supporting catalyst, a preparation method thereof, and an application thereof, aiming at the problems and deficiencies existing in the prior art. This catalyst can promote water decomposition and hydrogen desorption, and at the same time achieve the stability of the molybdenum-nickel alloy catalyst.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A molybdenum-nickel alloy-nickel oxide self-supporting catalyst, wherein the self-supporting catalyst comprises a nickel substrate, NiO nanosheets in-situ grown on the surface of the nickel substrate, and molybdenum-nickel alloy particles MoNi uniformly dispersed on the surface of the NiO nanosheets 4 .

[0007] In the above solution, the nickel substrate is nickel foam, nickel mesh or electrodeposited porous nickel.

[0008] In the above solution, the preparation method of the electrodeposited porous nickel is as follows: using a conductive net as the cathode and a graphite sheet as the anode, electro-depositing in a mixed solution of NiCl 2 and NH 4 Cl, taking it out, washing with water and drying to obtain the electrodeposited porous nickel.

[0009] In the above solution, the conductive net of the electrodeposited porous nickel is titanium net, stainless steel net or molybdenum net.

[0010] The preparation method of the molybdenum-nickel alloy-nickel oxide self-supporting catalyst comprises the following steps:

[0011] Immerse the nickel substrate in a mixed solution of molybdenum salt and urea, carry out a solvothermal reaction, wash and dry to obtain a nickel substrate with MoNiO nanosheet precursors grown thereon;

[0012] Place the MoNiO nanosheet precursors in a reducing atmosphere for heat preservation treatment to obtain the molybdenum-nickel alloy-nickel oxide self-supporting catalyst.

[0013] In the above solution, the concentration of the molybdenum salt in the mixed solution is 3-8 mmol / L, and the concentration of the urea is 80-150 mmol / L.

[0014] In the above solution, the solvothermal reaction temperature is 160-200 °C, and the time is 12-24 h.

[0015] In the above solution, the reducing atmosphere is ammonia, a mixture of ammonia and argon, or a mixture of hydrogen and argon; the volume concentration of ammonia in the mixture of ammonia and argon is 20-99%, and the volume concentration of hydrogen in the mixture of hydrogen and argon is 5-30%.

[0016] In the above solution, the heat preservation temperature is 400-500 °C, and the heat preservation time is 0.5-1.5 h.

[0017] Application of the molybdenum-nickel alloy-nickel oxide self-supporting catalyst in hydrogen production by electrolyzing water.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The formation of a strong electronic coupling between a molybdenum-nickel alloy with hydrogen desorption activity and a nickel oxide with water dissociation activity is an effective way to promote water decomposition and hydrogen desorption while achieving the stability of the molybdenum-nickel alloy catalyst and enhancing the alkaline hydrogen evolution performance. In addition, commercial alkaline electrolyzers mostly use nickel mesh substrates as electrodes. Therefore, developing a new process to in-situ construct a highly active nickel alloy-nickel oxide heterojunction hydrogen evolution catalyst on the surface of the Ni substrate to simultaneously promote the water dissociation and hydrogen desorption processes and obtain a high-efficiency large-current activity for alkaline hydrogen evolution has great commercial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the preparation process of the electrocatalyst material described in the present invention;

[0021] Figure 2 X-ray diffraction pattern of the final product prepared in Example 1 of the present invention;

[0022] Figure 3 Scanning electron microscope images of each step of the corresponding nickel mesh electrode in Example 1 of the present invention;

[0023] Figure 4 Transmission electron microscope image of the final product prepared in Example 1 of the present invention;

[0024] Figure 5 Scanning electron microscope image of the corresponding nickel mesh electrode in Comparative Example 1 of the present invention

[0025] Figure 6 Scanning electron microscope image of the corresponding nickel mesh electrode in Comparative Example 2 of the present invention;

[0026] Figure 7 Scanning electron microscope images of each step of the corresponding nickel foam electrode in Example 2 of the present invention;

[0027] Figure 8 Electrochemical polarization curves of the nickel mesh-based electrodes prepared in Examples 1, 2 and Comparative Example 2 of the present invention;

[0028] Figure 9 Scanning electron microscope images of the nickel mesh-based electrodes prepared in Example 3 and Comparative Example 3 of the present invention;

[0029] Figure 10 Electrochemical polarization curves of the nickel mesh-based electrodes prepared in Example 3 and Comparative Example 3 of the present invention;

[0030] Figure 11 Scanning electron microscope image of the porous nickel-based electrode prepared in Example 4 of the present invention;

[0031] Figure 12 Scanning electron microscope image of the porous nickel-based electrode prepared in Comparative Example 4 of the present invention;

[0032] Figure 13 This is the electrochemical polarization curve of the porous nickel-based electrode prepared in Comparative Example 4 and Example 4 of the present invention. Detailed implementation mode

[0033] The principles and features of the present invention are described below in conjunction with examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In addition, it is worth noting that the raw materials involved in the present invention are all ordinary commercially available products without special instructions.

[0034] Example 1

[0035] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, the schematic diagram of its preparation process is shown in Figure 1 , and the specific preparation method includes the following steps:

[0036] 1) The commercial Ni mesh was ultrasonically cleaned successively in acetone, ethanol, and deionized water, and then naturally dried for use;

[0037] 2) The Ni mesh obtained in step 1) was immersed in a mixed solution of 3 mmol / L ammonium molybdate tetrahydrate and 135 mmol / L urea, and kept at 200 °C in a reaction kettle for 24 h. After cooling to room temperature, it was washed and dried to obtain the MoNiO precursor grown on the surface of the Ni mesh;

[0038] 3) The MoNiO precursor obtained in step 2) was placed in a tubular furnace, heated to 450 °C at a heating rate of 5 °C / min in an atmosphere of a mixed gas of 95 vol% argon and 5 vol% hydrogen, and kept for reaction for 1 h. After cooling to room temperature, the nickel mesh-based molybdenum-nickel alloy-nickel oxide self-supporting composite catalyst was obtained.

[0039] Figure 2 This is the X-ray diffraction pattern of the product obtained in this example. From the XRD results, it can be clearly seen that the obtained product highly coincides with the characteristic peaks of the standard cards MoNi 4 PDF#07-0562 and NiO PDF#22-1189. It can be concluded that the molybdenum-nickel alloy-nickel oxide composite material was successfully synthesized by heat treatment in a reducing atmosphere.

[0040] Figure 3 These are the scanning electron microscope pictures of the original nickel mesh after cleaning, the nanoflowers grown after hydrothermal treatment, and the heat treatment reduction. It can be seen from the figure that the surface of the original commercial nickel mesh is smooth, with a very low specific surface area and insufficient exposure of catalytic active sites. Moreover, as a single component, nickel is greatly restricted in improving catalytic activity. After hydrothermal treatment, a large number of nanoflowers composed of nanosheets grow in-situ on the surface of the nickel mesh, and after reduction heat treatment at 450 °C in Ar / H 2 450 °C, the morphology basically does not change.

[0041] Figure 4 This is the transmission electron microscopy image of the product obtained in Example 1. It can be seen from the figure that dot-like molybdenum-nickel alloy particles are distributed on the nanosheets, and the particle size is concentrated in the range of 5-20 nm. Further analysis shows that two different lattice fringes can be observed, and the interplanar spacings are d = 0.207 and d = 0.208 nm, corresponding to MoNi 4 (121) and NiO(012) crystal planes respectively, which proves the formation of the heterointerface and can confirm that the structure is molybdenum-nickel alloy particles embedded on nickel oxide nanosheets.

[0042] Comparative Example 1

[0043] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0044] 1) Ultrasonically clean the commercial Ni mesh successively in acetone, ethanol, and deionized water, and then dry it naturally for later use;

[0045] 2) Immerse the Ni mesh obtained in step 1) in a mixed solution of 3 mmol / L ammonium molybdate tetrahydrate and 180 mmol / L urea, keep it at 200 °C in a reaction kettle for 12 h, wash and dry it after cooling to room temperature to obtain the MoNiO precursor grown on the surface of the Ni mesh;

[0046] 3) Put the MoNiO precursor obtained in step 2) into a tubular furnace, heat it to 450 °C at a heating rate of 5 °C / min in an atmosphere of a mixed gas of 95 vol% argon and 5 vol% hydrogen, keep it for reaction for 1 h, and cool it to room temperature to obtain the molybdenum-nickel alloy-nickel oxide self-supporting composite catalyst.

[0047] Figure 5 This is the scanning electron microscopy image of the electrode obtained in Comparative Example 1. It can be seen from the figure that when the content of urea is increased to 1.3 times and exceeds the concentration defined range, uniform nanosheets cannot be formed, and the balance of the weak base environment created by urea and ammonium ions is broken, which in turn affects the growth of nanosheets and cannot grow nanosheets uniformly.

[0048] Comparative Example 2

[0049] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0050] All other steps are the same as those in Example 1, only the reduction treatment holding temperature in step 3 becomes 650 °C. SEM analysis is performed on the obtained product.

[0051] As Figure 6 shown, when the reduction temperature of Ar / H 2 reaches 650 °C, holes appear in the nanosheets and a large amount of collapse occurs in the nanostructure of the nanoflowers, and the nanostructure is damaged. Just as Figure 8As shown in the LSV of Comparative Example 2, the performance of the electrode heat treated at 650°C is much lower than that of the electrode heat treated at 450°C in Example 1. -2 The overpotential of the hydrogen evolution reaction in Comparative Example 2 is 180 mV, which is higher than the 110 mV when heat treated at 450°C. Therefore, a suitable heat treatment temperature is necessary to maintain the structure of the nanosheets while improving the catalytic activity.

[0052] Example 2

[0053] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, the specific preparation method comprises the following steps:

[0054] 1) ultrasonically clean the commercial nickel foam in acetone, ethanol and deionized water in sequence, and then dry it naturally for later use;

[0055] 2) immersing the nickel foam obtained in step 1) in a mixed solution of 3 mmol / L ammonium molybdate tetrahydrate and 135 mmol / L urea, keeping the mixture at 200° C. for 12 h in a reactor, cooling the mixture to room temperature, washing and drying the mixture, and obtaining a MoNiO precursor grown on the surface of the nickel foam;

[0056] 3) placing the MoNiO precursor obtained in step 2) into a tubular furnace, heating to 450° C. at a heating rate of 5° C. / min in an atmosphere of a mixture of 95 vol% argon and 5 vol% hydrogen, and keeping the temperature for reaction for 1 hour, and cooling to room temperature to obtain a foamed nickel-based molybdenum-nickel alloy-nickel oxide self-supporting composite catalyst.

[0057] Figure 7 The following are scanning electron microscope images of molybdenum-nickel-oxygen nanosheets hydrothermally grown on commercial nickel foam and after heat treatment. It can be seen that the method of constructing nickel-containing nanosheets by micro-dissolution of nickel is feasible for different nickel metal substrates, and the morphology of the nanosheets does not change after heat treatment.

[0058] like Figure 8 The catalytic hydrogen evolution performance of the electrode materials obtained in Examples 1 and 2 and Comparative Example 2 in 1M KOH was compared. The results show that the nickel mesh-based nanosheet electrode, which has been treated with in-situ nanosheet growth and reduction at a suitable temperature, exhibits stronger catalytic hydrogen evolution activity than commercial nickel mesh under the same conditions, showing great application potential. When the current density is 10 mA cm -2 When the overpotential of hydrogen evolution reaction in Example 1 and Example 2 is 110mV and 90mV, and at 1000mA cm -2 Under high current conditions, the overpotential is as low as 680mV and 610mV, showing better electrocatalytic hydrogen evolution performance than the original nickel mesh.

[0059] Example 3

[0060] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0061] 1) Ultrasonically clean the commercial Ni mesh in acetone, ethanol, and deionized water in sequence, and then air-dry it for later use;

[0062] 2) Immerse the Ni mesh obtained in step 1) in a mixed solution of 3 mmol / L ammonium molybdate tetrahydrate and 135 mmol / L urea, keep it at 200 °C in a reaction kettle for 12 h, wash and dry it after cooling to room temperature to obtain the MoNiO precursor grown on the surface of the Ni mesh;

[0063] 3) Put the MoNiO precursor obtained in step 2) into a tubular furnace, heat it to 450 °C at a heating rate of 5 °C / min under the atmosphere of NH 3 and keep it for reaction for 1 h, and then cool it to room temperature to obtain the molybdenum-nickel alloy-nickel oxide self-supporting composite catalyst.

[0064] Comparative Example 3

[0065] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0066] Other steps are the same as those in Example 3, only the holding temperature for the reduction treatment in step 3) is changed to 550 °C and 650 °C.

[0067] As Figure 9 are the nickel mesh-based nanosheet electrodes after heat treatment at different reduction temperatures in the atmosphere of NH 3 in Example 3 and Comparative Example 3. It can be seen that the morphology of the nanosheets treated at 450 °C basically does not change. When the temperature rises to 550 °C, the nanoflowers begin to shrink, and a large amount of collapse occurs at 650 °C. Therefore, an appropriate heat treatment temperature is necessary for morphology regulation.

[0068] As Figure 10 shows the comparison of the catalytic hydrogen evolution performance of the electrode materials obtained in Example 3 and Comparative Example 3 in 1 M KOH. The results prove that the heat treatment in the ammonia atmosphere is equally effective and slightly better than that of the electrode after heat treatment with Ar / H 2 under the same conditions; when the temperature exceeds 550 °C, the morphology of the nanosheets collapses, resulting in a decrease in catalytic activity. When the current density is 10 mA cm -2 , the overpotential of the hydrogen evolution reaction in Example 3 is 89 mV, and under the high current condition of 1000 mA cm -2 , the overpotential is as low as 635 mV, showing better electrocatalytic hydrogen evolution performance than the original nickel mesh.

[0069] Example 4

[0070] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0071] 1) Ultrasonically clean the commercial Ni mesh successively in acetone, ethanol, and deionized water, and then air-dry it for later use;

[0072] 2) Use the nickel mesh obtained in step 1 as the cathode and a graphite sheet as the anode, and electro-deposit at a constant current of 1 A for 270 s in a mixed solution of NiCl 2 and NH 4 Cl. Take it out, wash it with water and dry it to obtain a porous nickel substrate;

[0073] 3) Immerse the porous nickel obtained in step 2 in a mixed solution of 3 mmol / L ammonium molybdate tetrahydrate and 135 mmol / L urea, keep it at 200 °C in a reaction kettle for 12 h, wash and dry it after cooling to room temperature to obtain a MoNiO precursor grown on the surface of the porous nickel;

[0074] 4) Put the MoNiO precursor grown on the surface of the porous nickel obtained in step 3 into a tubular furnace, heat it to 450 °C at a heating rate of 5 °C / min in an atmosphere of a mixed gas of 95 vol% argon and 5 vol% hydrogen, keep it for reaction for 1 h, and cool it to room temperature to obtain a porous nickel-based molybdenum-nickel alloy-nickel oxide self-supporting composite catalyst.

[0075] Figure 11 It is the scanning electron microscope image of the nickel mesh electrode corresponding to each step (after electro-deposition treatment, after reduction treatment) in Example 3. It can be seen from the figure that the electro-deposited porous nickel is composed of smooth nickel particles on the surface, and the pore diameters are distributed in the range of 5-30 μm. Nanosheets can grow uniformly on its surface through hydrothermal treatment, and the morphology basically does not change after heat treatment.

[0076] Comparative Example 4

[0077] A molybdenum-nickel alloy-nickel oxide self-supporting electrode material, and its specific preparation method includes the following steps:

[0078] 1) Ultrasonically clean the commercial Ni mesh successively in acetone, ethanol, and deionized water, and then air-dry it for later use;

[0079] 2) Use the nickel mesh obtained in step 1 as the cathode and a graphite sheet as the anode, and electro-deposit at a constant current of 1 A for 270 s in a mixed solution of NiCl 2 and NH 4 Cl. Take it out, wash it with water and dry it to obtain a porous nickel substrate;

[0080] 3) Immerse the porous nickel obtained in step 2) in a mixed solution of 15 mmol / L ammonium molybdate tetrahydrate and 135 mmol / L urea, keep it at 200 °C in a reaction kettle for 12 h, wash and dry it after cooling to room temperature to obtain the MoNiO precursor grown on the surface of the porous nickel;

[0081] 4) Put the MoNiO precursor grown on the surface of the porous nickel obtained in step 3) into a tubular furnace, heat it to 450 °C at a heating rate of 5 °C / min in an atmosphere of a mixed gas of 95 vol% argon and 5 vol% hydrogen, keep it for reaction for 1 h, and cool it to room temperature to obtain the catalyst of Comparative Example 4.

[0082] Figure 12 It is the scanning electron micrograph of the catalyst corresponding to Comparative Example 4. It can be seen that when the addition amount of molybdenum salt is increased by 5 times, it changes from the original nanosheets with curled edges to plate-like nanosheets, and there is no obvious change after heat treatment at 450 °C.

[0083] Figure 13 It is the comparison of the catalytic hydrogen evolution performance of the electrodes, nickel mesh, and porous nickel obtained in Comparative Example 3 and Example 4 in 1 M KOH. The results prove that when the current density is 10 mA cm -2 , the overpotential of the hydrogen evolution reaction in Example 4 is 23 mV, and the overpotential of the hydrogen evolution reaction in Comparative Example 4 is 54 mV; and under the high-current condition of 1000 mA cm -2 , the overpotential of Example 4 is as low as 330 mV, showing better electrocatalytic hydrogen evolution performance than 20% PtC. The overpotential of Comparative Example 4 is 445 mV. In the present invention, due to the use of a low concentration of molybdenum salt, the finally obtained molybdenum-nickel alloy ratio is 1:4, and the obtained nickel oxide nanosheets do not contain other doping elements, such as molybdenum element doping, so as to obtain the MoNi 4 / NiO composite catalyst with excellent catalytic activity. The molybdenum-nickel alloy obtained in the present invention is MoNi 4 , which is a bimetallic alloy with more excellent catalytic performance, and its structure is alloy particles embedded on NiO nanosheets. Through the interaction and interface effect between the metal-oxide carriers, excellent catalytic activity is achieved, and the 5-30 micron-sized pore structure and the nanoflowers formed by the curling of a large number of nanosheets are three-dimensional. The present invention emphasizes the mutual relationship between MoNi 4 -NiO carriers, so as to increase the reaction surface ratio of each unit metal of the bimetallic alloy catalyst on the carrier, provide a high-surface-area carrier to increase the metal loading rate, and prevent the aggregation of the loaded metal substances during the preparation and catalytic use processes, thereby improving the dispersibility and stability and obtaining strong catalytic activity.

[0084] It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A molybdenum-nickel alloy-nickel oxide self-supporting catalyst, characterized in that: The self-supporting catalyst comprises a nickel substrate, NiO nanosheets grown in situ on the surface of the nickel substrate, and molybdenum-nickel alloy particles MoNi4 uniformly dispersed on the surface of the NiO nanosheets.

2. The molybdenum-nickel alloy-nickel oxide self-supporting catalyst according to claim 1, characterized in that: The nickel substrate is foamed nickel, nickel mesh or electrodeposited porous nickel.

3. The molybdenum-nickel alloy-nickel oxide self-supporting catalyst according to claim 1, characterized in that: The preparation method of the electrodeposited porous nickel is as follows: using a conductive mesh as a cathode and a graphite sheet as an anode, electrodepositing in a mixed solution of NiCl2 and NH4Cl in a constant current manner, taking out, washing and drying to obtain the electrodeposited porous nickel.

4. The molybdenum-nickel alloy-nickel oxide self-supporting catalyst according to claim 1, characterized in that: The conductive mesh for electrodepositing porous nickel is a titanium mesh, a stainless steel mesh or a molybdenum mesh.

5. The method for preparing the molybdenum-nickel alloy-nickel oxide self-supporting catalyst according to any one of claims 1 to 4, characterized in that: The steps include: The nickel substrate is immersed in a mixed solution of molybdenum salt and urea to perform a solvothermal reaction, and then washed and dried to obtain a nickel substrate on which a MoNiO nanosheet precursor is grown; The MoNiO nanosheet precursor is placed in a reducing atmosphere for heat preservation treatment to obtain the molybdenum-nickel alloy-nickel oxide self-supporting catalyst.

6. The preparation method according to claim 5, characterized in that: The concentration of the molybdenum salt in the mixed solution is 3-8 mmol / L, and the concentration of the urea is 80-150 mmol / L.

7. The preparation method according to claim 5, characterized in that: The solvent thermal reaction temperature is 160-200° C. and the time is 12-24 hours.

8. The preparation method according to claim 5, characterized in that: The reducing atmosphere is ammonia, a mixture of ammonia and argon, or a mixture of hydrogen and argon; the volume concentration of ammonia in the mixture of ammonia and argon is 20-99%, and the volume concentration of hydrogen in the mixture of hydrogen and argon is 5-30%.

9. The preparation method according to claim 5, characterized in that: The insulation temperature is 400-500° C., and the insulation time is 0.5-1.5 h.

10. Use of the molybdenum-nickel alloy-nickel oxide self-supporting catalyst according to any one of claims 1 to 4 in hydrogen production by water electrolysis.

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