A nickel-molybdenum composite electrode material, its preparation method and application

Abstract

This invention belongs to the field of water electrolysis for hydrogen production and catalysis technology, and discloses a nickel-molybdenum composite electrode material and its preparation method and application. The method includes: dissolving nickel salt, molybdenum salt, and organic ligand separately in deionized water to obtain a homogeneous solution; mixing and stirring the homogeneous solution to react and generate a precipitate, obtaining a NiMo-MOF precursor slurry; centrifuging, washing, and drying the NiMo-MOF precursor slurry to obtain NiMo-MOF powder; calcining the NiMo-MOF powder in air and cooling to obtain NiMoO4 powder material; mixing the NiMoO4 powder material with conductive carbon and annealing in a hydrogen / argon mixed atmosphere, followed by cooling to obtain the nickel-molybdenum composite electrode material. The NiMo-based MOF-derived catalytic material obtained by this invention exhibits excellent structural uniformity, active site utilization, and electrochemical stability.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production and catalysis technology, and relates to a nickel-molybdenum composite electrode material, its preparation method and application. Background Technology

[0002] Against the backdrop of global energy structure transformation and the rapid development of clean energy, hydrogen energy, with its high energy density and zero carbon emissions, is considered an important pathway to achieving sustainable energy development. Hydrogen production through water electrolysis, as an environmentally friendly and high-purity method, occupies a central position in the future energy system. Developing efficient HER catalysts plays a crucial role in reducing reaction overpotential and improving overall energy conversion efficiency.

[0003] Currently, although platinum-based noble metal materials exhibit near-thermodynamical limit activity in HER catalysis, their high cost and resource scarcity severely restrict their application in industrial-scale hydrogen production. Therefore, developing low-cost, highly active, and long-life non-noble metal-based catalysts has become a research hotspot.

[0004] Among numerous candidate materials, NiMo-based catalysts are considered one of the most promising non-noble metal HER catalytic systems due to their excellent electrical conductivity, synergistic effects, and tunable electronic structure. However, NiMo catalysts prepared by traditional co-precipitation or high-temperature calcination processes often suffer from problems such as particle agglomeration, structural collapse, and insufficient exposure of active sites, which limits their catalytic activity and stability during water electrolysis. Furthermore, high-temperature treatment can induce grain growth and phase transformation, making it difficult to maintain the intrinsic structural advantages of the catalyst.

[0005] Therefore, how to achieve high stability and high binding strength of the NiMo system while maintaining its active structural characteristics is a key scientific and engineering problem that urgently needs to be solved in the field of water electrolysis catalysis. Summary of the Invention

[0006] The purpose of this invention is to provide a nickel-molybdenum composite electrode material, its preparation method, and its application, thereby solving the problems of poor structural stability, easy morphological collapse, and insufficient exposure of active sites in existing NiMo-based catalytic materials.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a nickel-molybdenum composite electrode material includes: Nickel salt, molybdenum salt and organic ligand were dissolved in deionized water to obtain homogeneous solutions. The homogeneous solution was mixed and stirred, and the reaction produced a precipitate to obtain the NiMo-MOF precursor slurry. The NiMo-MOF precursor slurry was centrifuged, washed, and dried to obtain NiMo-MOF powder. NiMo-MOF powder was calcined in air and then cooled to obtain NiMoO4 powder material. NiMoO4 powder was mixed with conductive carbon and annealed in a hydrogen / argon mixed atmosphere. After cooling, a nickel-molybdenum composite electrode material was obtained.

[0008] Furthermore, both the nickel salt and the molybdenum salt are one or more of the following: chloride salt, nitrate salt, sulfate salt, acetate salt, and acetylacetone salt. The organic ligand is dimethylimidazole.

[0009] Furthermore, the molar ratio of nickel salt, molybdenum salt and organic ligand is 1:1:3, the reaction temperature is room temperature, and the reaction time is 50-80 h.

[0010] Furthermore, the centrifugation speed is 3000~8000 rpm, the centrifugation time is 5~15 min, and the drying temperature is 60~80 ℃.

[0011] Furthermore, the washing process involves alternating between deionized water and ethanol, washing 2 to 5 times each.

[0012] Furthermore, during the calcination process, the calcination temperature is 400~700 ℃, the holding time is 2 h, and the heating rate is 1~5 ℃·min. -1 .

[0013] Furthermore, the conductive carbon is one or more of acetylene black, carbon nanotubes, and graphene. The mass of conductive carbon is 10 wt% to 40 wt% of the mass of NiMoO4 powder material.

[0014] Furthermore, during the annealing process, the annealing temperature is 300~600 ℃, the holding time is 2 h, and the heating rate is 1~5 ℃·min. -1 .

[0015] A nickel-molybdenum composite electrode material prepared by the aforementioned method.

[0016] The application of the nickel-molybdenum composite electrode material in the preparation of water electrolysis devices for alkaline electrolyte systems.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a nickel-molybdenum composite electrode material. Using nickel and molybdenum salts as metal sources and dimethylimidazole as an organic solvent as a ligand, NiMo-MOF powder is constructed as a precursor by introducing organic ligands. Subsequently, a two-step heat treatment process combining air calcination and hydrogen reduction is used to transform the precursor's structure, forming a NiMo alloy-oxide composite phase structure while maintaining its original morphology. This constructs a stable metal / oxide interface and significantly enhances electronic conductivity and catalytic activity. Simultaneously, a conductive carbon source is introduced during the heat treatment process to form a continuous conductive network, improving the overall conductivity and structural stability of the material. This invention employs a step-by-step preparation process: first, coordination synthesis of the NiMo-MOF precursor; then, air calcination to produce NiMoO4; and finally, compounding with conductive carbon and annealing with hydrogen and argon. The process is simple, parameters are controllable, and material morphology is adjustable. It utilizes a direct MOF derivation route, eliminating the need for ball milling, cold spraying, or multi-stage coating processes. The preparation process is simple, the conditions are mild, raw materials are widely available, and the cost is low. Using NiMo-MOF as a precursor, in-situ transformation of metal components is achieved through heat treatment under a controlled atmosphere. The metal nodes in the MOF are highly dispersed under the confinement of organic ligands, forming NiMo-based active structures with metal-metal or metal-oxide coexistence during hydrogen / argon annealing. This effectively avoids the metal agglomeration and phase separation problems encountered in traditional powder preparation, resulting in a catalytic material with abundant exposed active sites and excellent electrocatalytic activity. By controlling the precursor composition and heat treatment conditions, the material composition and structure can be controllably adjusted. The resulting catalytic material is firmly bonded to the substrate, exhibiting excellent structural stability and good scalability. It demonstrates good reproducibility and scale-up potential, making it suitable for large-scale preparation. Compared to traditional catalytic electrodes prepared from bulk alloys or physically mixed powders, the NiMo-based MOF-derived catalytic material obtained in this invention exhibits superior structural uniformity, active site utilization, and electrochemical stability. It can be directly used as a cathode material in water electrolysis hydrogen production systems, providing a new technical approach for the development of high-performance, low-cost electrolyzer cathode materials.

[0018] Furthermore, soluble nickel and molybdenum salts such as chlorides, nitrates, and sulfates are selected, exhibiting good water solubility and high degree of dissociation. These salts can disperse rapidly and uniformly in aqueous solutions, facilitating thorough coordination reactions with organic ligands and ensuring the regular morphology and high crystallinity of the NiMo-MOF powder. Dimethylimidazolium is chosen as the organic ligand due to its strong coordination ability and stable framework structure. This allows for precise control of the MOF's microstructure and pore structure, effectively anchoring nickel and molybdenum metal ions and preventing the migration and aggregation of metal components during high-temperature calcination.

[0019] Furthermore, the 1:1:3 molar ratio allows the metal ions and organic ligands to achieve the optimal coordination stoichiometry, ensuring complete coordination reaction without any free metal ions or excess ligand residue, thus reducing the burden on subsequent washing and purification. A prolonged room-temperature stirring reaction of 50–80 hours facilitates slow and complete MOF crystal growth, resulting in a uniform, well-structured rod-shaped hierarchical microstructure, increasing specific surface area and the number of active sites.

[0020] Furthermore, by limiting the centrifugation speed and time, the solid-liquid separation of the precursor can be achieved efficiently, fully retaining fine MOF precipitate particles and preventing the loss of small active components, while effectively separating unreacted impurity ions in the supernatant. Low-temperature drying at 60~80℃ can quickly remove moisture while avoiding the collapse of the MOF framework and particle agglomeration caused by high temperatures, thus preserving the porous microstructure of the precursor and maintaining a high specific surface area.

[0021] Furthermore, deionized water can effectively remove residual metal ions and water-soluble salt impurities; ethanol can replace the adsorbed water on the particle surface and dissolve residual organic ligands and small organic molecule impurities, resulting in thorough impurity removal through dual washing. Alternating washing 2-5 times ensures effective impurity removal while avoiding excessive washing that could lead to the loss of active precursors, thus balancing product purity and yield.

[0022] Furthermore, air calcination at 400–700 °C completely decomposes the MOF organic framework, directionally generating pure-phase NiMoO4 oxide without any residual carbon impurities. This moderate temperature range ensures complete pyrolysis of the framework while avoiding excessive grain growth and a decrease in specific surface area due to excessively high temperatures. (1–5 °C·min) -1 Slow heating is used to prevent rapid heating from causing instantaneous thermal decomposition and structural collapse of the MOF framework, ensuring that the generated NiMoO4 retains the hierarchical porous structure derived from the precursor. Holding at a constant temperature for 2 hours ensures sufficient phase transformation, uniform grain growth, and stable crystal structure, providing an ideal oxide matrix for subsequent hydrogen-argon annealing to construct the alloy and oxygen defect structure.

[0023] Furthermore, highly conductive carbon materials such as acetylene black, carbon nanotubes, and graphene are selected. These materials possess excellent intrinsic conductivity and can construct a continuous conductive network within the NiMoO4 powder, significantly reducing the charge transfer resistance of the electrode material and accelerating the electron transport kinetics of the water electrolysis reaction. The optimal addition range is 10wt%–40wt%. Too low an addition will prevent the formation of a complete conductive pathway; too high an addition will cover the catalytic active sites and reduce overall catalytic activity. This range balances conductivity and intrinsic catalytic activity.

[0024] Furthermore, annealing in a weakly reducing hydrogen-argon atmosphere at 300–600 °C can induce partial reduction of NiMoO4 under mild conditions, resulting in the in-situ formation of the MoNi4 alloy phase and the construction of abundant oxygen vacancy defects. These oxygen defects, in conjunction with the alloy phase, provide a large number of hydrogen evolution active sites. (1–5 °C·min) -1 Slow heating followed by 2 hours of constant temperature maintenance ensures a uniform and complete reduction reaction, allowing for controllable phase composition and preventing the formation of impurity phases due to localized over-reduction. A hydrogen-argon mixed atmosphere prevents high-temperature oxidation of the material, while conductive carbon facilitates interface modification, optimizing the electronic structure of the electrode surface and significantly improving the stability and efficiency of hydrogen evolution catalysis under alkaline conditions.

[0025] This invention also provides a nickel-molybdenum composite electrode material with stable structure, uniform morphology, and high phase purity. It exhibits a multi-level porous microstructure, large specific surface area, and uniform elemental distribution, exposing ample electrocatalytic active sites. It combines a MoNi4 alloy phase, an oxygen-deficient molybdenum oxide phase, and a conductive carbon network, resulting in strong interfacial coupling, fast electron conduction rate, and low charge transfer resistance. It is corrosion-resistant under alkaline conditions, its structure is not easily collapsed, and it possesses excellent long-cycle catalytic stability.

[0026] This invention also provides an application of a nickel-molybdenum composite electrode material in the preparation of alkaline electrolyte system water electrolysis devices. It exhibits low hydrogen evolution overpotential and high current density response in alkaline electrolytes, demonstrating electrocatalytic hydrogen evolution activity far superior to conventional molybdenum-based and nickel-based electrode materials. Furthermore, it is well-suited to the operating environment of alkaline water electrolysis hydrogen production devices, is resistant to alkali corrosion, has a long cycle life, and can reduce energy consumption in water electrolysis hydrogen production. It has broad application prospects in alkaline water electrolysis hydrogen production devices, hydrogen energy storage supporting electrolysis devices, and other fields. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The MoNi4 / MoO in Embodiment 1 of the present invention 3-x Electrode material preparation flowchart.

[0029] Figure 2 The images show the SEM and EDS spectra of the NiMo-MOF powder prepared in Example 1 of this invention.

[0030] Figure 3 The images show a comparison of SEM images of the electrode materials prepared in Example 1 and Comparative Examples 1-3 of the present invention.

[0031] Figure 4 MoNi4 / MoO prepared for Example 1 of the present invention 3-x XRD and Raman plots of the electrode material.

[0032] Figure 5 This is a comparison diagram of the electrochemical performance of the electrode materials prepared in Example 1 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0035] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0037] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings: This invention provides a method for preparing a nickel-molybdenum composite electrode material, specifically including the following steps: Step 1: Dissolve nickel salt, molybdenum salt and organic ligand separately in deionized water to obtain homogeneous solutions. Mix the solutions and stir at room temperature for a certain time to allow them to react fully and form a precipitate, thus obtaining NiMo-MOF precursor slurry. Step 2: The precursor slurry obtained in Step 1 is centrifuged and washed with deionized water and ethanol in sequence to remove residual ions and organic matter; then dried at a set temperature to obtain NiMo-MOF powder for later use. Step 3: The NiMo-MOF powder obtained in Step 2 is evenly spread in a ceramic boat, placed in a tube furnace, and calcined in an air atmosphere. After calcination, it is naturally cooled to obtain NiMoO4 powder material. Step 4: The NiMoO4 powder material obtained in Step 3 is thoroughly mixed with a certain amount of conductive carbon and then evenly spread in a ceramic boat. The boat is placed in a tube furnace and annealed in a hydrogen / argon mixed atmosphere. After annealing, the material is naturally cooled to obtain the final NiMo-based composite powder catalytic electrode material.

[0041] Preferably, in step 1, the precursor salt is one or more of chloride, nitrate, sulfate, acetate, and acetylacetone salts, and the organic ligand is dimethylimidazole.

[0042] The molar ratio of nickel salt, molybdenum salt and organic ligand is 1:1:3, the solvent volume is 80 mL, and the reaction time is 50-80 h.

[0043] Preferably, in step 2, the centrifugation speed is 3000~8000 rpm and the centrifugation time is 5~15 min. The washing process alternates between deionized water and ethanol 2~5 times each to effectively remove metal ions that did not participate in the coordination reaction and residual organic ligands; the drying temperature is 60~80 ℃.

[0044] Preferably, in step 3, the calcination temperature is 400~700 ℃, the holding time is 2 h, and the heating rate is 1~5 ℃·min. -1 .

[0045] Preferably, in step 4, the conductive carbon is one or more of acetylene black, carbon nanotubes, and graphene, and its added mass is 10 wt% to 40 wt% of the mass of NiMoO4 powder material.

[0046] Annealing was performed in a hydrogen / argon mixed atmosphere (hydrogen component 10%) at temperatures of 300–600 °C for 2 h at a heating rate of 1–5 °C / min. -1 .

[0047] The technical solution of the present invention will be further described in detail below through specific embodiments: Example 1: MoNi4 / MoO 3-x Electrode preparation methods, such as Figure 1 As shown, the specific steps include: Step 1: Add 0.04 mmol NiCl2·6H2O and 0.006 mmol (NH4)Mo7O 24 0.12 mmol of dimethylimidazole organic solvent was dissolved in 80 mL of deionized water, and the mixture was stirred for 60 h until the reaction was complete and a precipitate was formed, thus obtaining the NiMo-MOF precursor slurry. Step 2: The obtained NiMo-MOF precursor slurry was collected by centrifugation and washed three times with deionized water until the supernatant was colorless. Then, it was washed with anhydrous ethanol to remove residual impurities. Finally, the precipitate was dried in a vacuum oven at 60°C to obtain NiMo-MOF powder. Step 3: Weigh 200 mg of NiMo-MOF powder and spread it evenly in a ceramic boat. Transfer it to a tube furnace and calcine it at 500 °C for 2 h in air atmosphere. The heating rate is controlled at 2 °C / min. After natural cooling, NiMoO4 powder material is obtained. Step 4: Weigh 100 mg of NiMoO4 powder obtained in Step 3, add conductive carbon acetylene black at 30 wt% of its mass, mix thoroughly with the NiMoO4 powder, transfer to a ceramic boat, place in a tube furnace, and anneal under a hydrogen / argon mixed atmosphere (hydrogen gas fraction 10%). Heat to 450 ℃ at a heating rate of 2 ℃ / min and hold for 2 h. After annealing, allow the furnace to cool naturally to obtain MoNi4 / MoO4. 3-x Electrode materials.

[0048] MoNi4 / MoO prepared according to the above steps 3-x Electrode materials are used as cathodes in the preparation of alkaline electrolyte system water electrolysis devices.

[0049] Example 2: MoNi4 / MoO3-x The preparation method of the -30 electrode specifically includes the following steps: Step 1: Add 0.04 mmol NiCl2·6H2O and 0.006 mmol (NH4)Mo7O 24 0.12 mmol of dimethylimidazole organic solvent was dissolved in 80 mL of deionized water, and the mixture was stirred for 30 h until the reaction was complete and a precipitate was formed, thus obtaining the NiMo-MOF precursor slurry. Step 2: The obtained NiMo-MOF precursor slurry was collected by centrifugation and washed three times with deionized water until the supernatant was colorless. Then, it was washed with anhydrous ethanol to remove residual impurities. Finally, the precipitate was dried in a vacuum oven at 60°C to obtain NiMo-MOF powder. Step 3: Weigh 200 mg of NiMo-MOF powder and spread it evenly in a ceramic boat. Transfer it to a tube furnace and calcine it at 500 °C for 2 h in air atmosphere. The heating rate is controlled at 2 °C / min. After natural cooling, NiMoO4 powder material is obtained. Step 4: Weigh 100 mg of NiMoO4 powder obtained in Step 3, add conductive carbon acetylene black at 30 wt% of its mass, mix thoroughly with the NiMoO4 powder, transfer to a ceramic boat, place in a tube furnace, and anneal under a hydrogen / argon mixed atmosphere (hydrogen gas fraction 10%). Heat to 450 ℃ at a heating rate of 2 ℃ / min and hold for 2 h. After annealing, allow the furnace to cool naturally to obtain MoNi4 / MoO4. 3-x -30 electrode material.

[0050] Example 3: MoNi4 / MoO 3-x The preparation method of the -90 electrode specifically includes the following steps: Step 1: Add 0.04 mmol NiCl2·6H2O and 0.006 mmol (NH4)Mo7O 24 0.12 mmol of dimethylimidazole organic solvent was dissolved in 80 mL of deionized water, and the mixture was stirred for 90 h until the reaction was complete and a precipitate was formed, thus obtaining NiMo-MOF precursor slurry; Step 2: The obtained NiMo-MOF precursor slurry was collected by centrifugation and washed three times with deionized water until the supernatant was colorless. Then, it was washed with anhydrous ethanol to remove residual impurities. Finally, the precipitate was dried in a vacuum oven at 60°C to obtain NiMo-MOF powder. Step 3: Weigh 200 mg of NiMo-MOF powder and spread it evenly in a ceramic boat. Transfer it to a tube furnace and calcine it at 500 °C for 2 h in air atmosphere. The heating rate is controlled at 2 °C / min. After natural cooling, NiMoO4 powder material is obtained. Step 4: Weigh 100 mg of NiMoO4 powder obtained in Step 3, add conductive carbon acetylene black at 30 wt% of its mass, mix thoroughly with the NiMoO4 powder, transfer to a ceramic boat, place in a tube furnace, and anneal under a hydrogen / argon mixed atmosphere (hydrogen gas fraction 10%). Heat to 450 ℃ at a heating rate of 2 ℃ / min and hold for 2 h. After annealing, allow the furnace to cool naturally to obtain MoNi4 / MoO4. 3-x -90 electrode material.

[0051] Example 4: MoNi4 / MoO 3-x The preparation method of the -200 electrode specifically includes the following steps: Step 1: Add 0.04 mmol NiCl2·6H2O and 0.006 mmol (NH4)Mo7O 24 0.12 mmol of dimethylimidazole organic solvent was dissolved in 80 mL of deionized water, and the mixture was stirred for 60 h until the reaction was complete and a precipitate was formed, thus obtaining the NiMo-MOF precursor slurry. Step 2: The obtained NiMo-MOF precursor slurry was collected by centrifugation and washed three times with deionized water until the supernatant was colorless. Then, it was washed with anhydrous ethanol to remove residual impurities. Finally, the precipitate was dried in a vacuum oven at 60°C to obtain NiMo-MOF powder. Step 3: Weigh 200 mg of NiMo-MOF powder and spread it evenly in a ceramic boat. Transfer it to a tube furnace and calcine it at 500 °C for 2 h in air atmosphere. The heating rate is controlled at 2 °C / min. After natural cooling, NiMoO4 powder material is obtained. Step 4: Weigh 100 mg of NiMoO4 powder obtained in Step 3, add conductive carbon acetylene black at 30 wt% of its mass, mix thoroughly with the NiMoO4 powder, transfer to a ceramic boat, place in a tube furnace, and anneal under a hydrogen / argon mixed atmosphere (hydrogen gas fraction 10%). Heat to 200 ℃ at a heating rate of 2 ℃ / min and hold for 2 h. After annealing, allow the furnace to cool naturally to obtain MoNi4 / MoO4. 3-x -200 electrode material.

[0052] Example 5: MoNi4 / MoO 3-x The preparation method of the -700 electrode specifically includes the following steps: Step 1: Add 0.04 mmol NiCl2·6H2O and 0.006 mmol (NH4)Mo7O 24 0.12 mmol of dimethylimidazole organic solvent was dissolved in 80 mL of deionized water, and the mixture was stirred for 60 h until the reaction was complete and a precipitate was formed, thus obtaining the NiMo-MOF precursor slurry. Step 2: The obtained NiMo-MOF precursor slurry was collected by centrifugation and washed three times with deionized water until the supernatant was colorless. Then, it was washed with anhydrous ethanol to remove residual impurities. Finally, the precipitate was dried in a vacuum oven at 60°C to obtain NiMo-MOF powder. Step 3: Weigh 200 mg of NiMo-MOF powder and spread it evenly in a ceramic boat. Transfer it to a tube furnace and calcine it at 500 °C for 2 h in air atmosphere. The heating rate is controlled at 2 °C / min. After natural cooling, NiMoO4 powder material is obtained. Step 4: Weigh 100 mg of NiMoO4 powder obtained in Step 3, add conductive carbon acetylene black at 30 wt% of its mass, mix thoroughly with the NiMoO4 powder, transfer to a ceramic boat, place in a tube furnace, and anneal under a hydrogen / argon mixed atmosphere (hydrogen gas fraction 10%). Heat to 700 ℃ at a heating rate of 2 ℃ / min and hold for 2 h. After annealing, allow the furnace to cool naturally to obtain MoNi4 / MoO4. 3-x -700 electrode material.

[0053] Comparative Example 1: The difference from Example 1 is that the NiMo-MOF powder obtained in step 2 is directly subjected to hydrogen / argon atmosphere annealing treatment, while the remaining steps are the same as in Example 1, to obtain MOF-H electrode material.

[0054] The MOF-H electrode material prepared according to the above steps is used as the cathode.

[0055] Comparative Example 2: The difference from Example 1 is that the NiMo-MOF powder obtained in step 2 is transferred together with conductive carbon acetylene black into a ceramic boat and annealed in a hydrogen / argon mixed atmosphere. The remaining steps are the same as in Example 1 to obtain MOF-HC electrode material.

[0056] The MOF-HC electrode material prepared according to the above steps is used as a cathode in the preparation of alkaline electrolyte system water electrolysis devices.

[0057] Comparative Example 3: The difference from Example 1 is that 100 mg of NiMoO4 powder material obtained in step 3 was weighed, transferred to a ceramic boat, placed in a tube furnace, and annealed in a hydrogen / argon mixed atmosphere. The remaining steps were the same as in Example 1 to obtain MOF-AH electrode material.

[0058] The MOF-AH electrode material prepared according to the above steps is used as a cathode in the preparation of alkaline electrolyte system water electrolysis devices.

[0059] Characterization analysis of the material structure and composition of Embodiment 1 and Comparative Examples 1-3 of the present invention: like Figure 2 As shown in the SEM image of the NiMo-MOF powder prepared in Example 1 of this invention, the NiMo-MOF powder exhibits a typical rod-like / columnar hierarchical structure. At low magnification, it shows a large number of uniformly distributed micron-sized rod-like particles. At high magnification, the rod-like structure has a smooth surface and uniform size, which is a typical crystal growth morphology of MOF materials. EDS energy dispersive spectroscopy images show that Ni, Mo, O, and N elements are uniformly distributed in the rod-like structure, with no obvious elemental segregation. The N element originates from the organic ligand dimethylimidazole, proving that Ni and Mo metal ions successfully coordinate with the organic ligand, and the MOF precursor was successfully synthesized.

[0060] like Figure 3 As shown, the MoNi4 / MoO prepared in Example 1 of the invention... 3-x By comparing the SEM images of the electrode with those prepared in Comparative Examples 1-3, it can be seen that... Figure 3 (a) is the MOF-H electrode prepared in Comparative Example 1. It was directly annealed without air calcination. The material still maintains the bulk layered aggregate morphology of the precursor, with no obvious nanoparticles generated. The structure is dense and without hierarchical structure, and the active sites are not sufficiently exposed. Figure 3 (b) is the MOF-HC electrode prepared in Comparative Example 2. It was not calcined in air, but only annealed with conductive carbon. The material exhibits irregular spherical agglomerates without regular rod-shaped structures. The particle size is uneven and the agglomeration is severe, making it impossible to form an ordered catalytic active structure. Figure 3 (c) is the MOF-AH electrode prepared in Comparative Example 3. After air calcination but without the addition of conductive carbon for annealing, the material presents as an amorphous agglomerated powder. The rod-shaped structure completely collapses, the particles are broken and have no fixed morphology, and the structural stability is poor, which is not conducive to electron transport and reaction mass transfer. Figure 3 (d) MoNi4 / MoO prepared in Example 1 of the invention 3-x The electrode retains the rod / column structure of the precursor, but the surface becomes rough and is covered with nanoscale particles. This is due to NiMoO4 formed by air calcination, followed by reduction via hydrogen-argon annealing to generate MoNi4 alloy and oxygen-deficient MoO. 3-xIts characteristic morphology, complete structure and multi-level rough surface are conducive to the exposure of active sites in electrocatalytic reactions.

[0061] like Figure 4 As shown, the MoNi4 / MoO prepared from Example 1 of the present invention 3-x XRD patterns of electrode materials ( Figure 4 a) It can be seen that the characteristic diffraction peaks of the sample match the standard cards for MoNi4 (PDF#65-5480) and MoO2 (PDF#32-0671), proving that the MoNi4 alloy phase was successfully formed in the material, while retaining the molybdenum oxide phase (MoO2). 3-x The absence of obvious impurity peaks indicates that the phase composition during the preparation process was controllable, and the target product was successfully synthesized. The MoNi4 / MoO4 prepared from Example 1 of this invention... 3-x Raman spectra of electrode materials ( Figure 4 b) It can be seen that at low wavenumbers (200~400 cm⁻¹) -1 ) and high wave number (800~1000 cm -1 Characteristic vibrational peaks of the Mo-O bond appeared in the region, with the strong peaks at high wavenumbers corresponding to MoO. 3-x The vibration of the Mo=O double bond in the material proves the existence of an oxygen-deficient molybdenum oxide phase, which is corroborated by the XRD results, indicating that the material has both an alloy phase and a defect oxide phase.

[0062] Comparative analysis of the electrochemical performance of Example 1 and Comparative Examples 1-3 of the present invention: A three-electrode system based on a rotating disk electrode (RDE) was used, with the electrode materials obtained in Example 1 and Comparative Examples 1-3 serving as the working electrodes for the hydrogen evolution reaction in an alkaline electrolyte. In the three-electrode test system, a platinum wire was used as the counter electrode, a mercury / mercury oxide electrode as the reference electrode, and 30% wt potassium hydroxide was selected as the electrolyte.

[0063] Electrochemical data were measured using linear voltammetry and electrochemical impedance spectroscopy. The linear voltammetry scan rate was 5 mV / s, the electrochemical impedance spectroscopy test potential was -1.3 V vs. Hg / HgO, the electrochemical amplitude was 10 mV, and the frequency range was 10. 6 ~10 -1 Hz. The test results are shown in Table 1.

[0064] Table 1 summarizes and compares the electrode electrochemical performance obtained from the above implementation cases.

[0065] As can be seen from Table 1, the MoNi4 / MoO prepared in Example 1 of this invention 3-x Electrode at 100 mA / cm 2The overpotential at the current density is only 147 mV, which is significantly lower than that of the electrodes prepared in Comparative Examples 1-3, indicating that the MoNi4 / MoO prepared in Example 1 of this invention... 3-x The electrode exhibits superior electrocatalytic hydrogen evolution performance.

[0066] MoNi4 / MoO prepared in Example 1 of this invention 3-x The charge transfer resistance of the electrode is less than that of the electrodes prepared in Comparative Examples 1-3, indicating that the MoNi4 / MoO prepared in Example 1 of this invention... 3-x The rapid charge transfer between the electrode interface and the electrolyte demonstrates its high hydrogen evolution catalytic activity.

[0067] like Figure 5 As shown, Figure 5 (a) The linear sweep voltammetry curve is obtained with current density (mA) cm -2 The graph (with the negative direction representing the hydrogen evolution reaction) is plotted on the ordinate and potential (V vs. RHE) on the abscissa, reflecting the hydrogen evolution catalytic activity of the material. Example 1: MoNi4 / MoO 3-x When the electrodes achieve the same current density, the required overpotential is significantly lower than that of Comparative Examples 1-3. The peak potentials of the curves for MOF-AH, MOF-H, and MOF-HC materials are more positive (lower overpotentials), indicating that the material in Example 1 has superior hydrogen evolution catalytic activity and can drive the reaction at a lower overpotential. Among Comparative Examples 1-3, MOF-AH has the worst activity, followed by MOF-H. The activity of MOF-HC is better than the former two, but still much lower than that of Example 1, proving that the two-step treatment of air calcination + conductive carbon annealing is the key to achieving high catalytic activity.

[0068] Figure 5 (b) The electrochemical impedance spectroscopy curve has the real part impedance (Ω) as the abscissa and the imaginary part impedance (Ω) as the ordinate. The intercept of the curve with the horizontal axis represents the solution resistance, and the diameter of the semicircle represents the charge transfer resistance (Rct). The smaller the Rct, the stronger the electron transport ability of the material and the faster the catalytic reaction kinetics.

[0069] MoNi4 / MoO in Example 1 3-xThe semicircular diameter of the electrode is much smaller than that of MOF-AH, MOF-H, and MOF-HC, and the magnified high-frequency region in the illustration clearly shows that the charge transfer resistance of Example 1 is significantly lower, indicating that it has superior electron transport efficiency and faster reaction kinetics. Among Comparative Examples 1 to 3, MOF-AH has the largest semicircular diameter, the highest charge transfer resistance, and the worst electron transport capability; the impedance of MOF-H and MOF-HC decreases in that order, indicating that adding conductive carbon can improve conductivity to a certain extent, but the material without air calcination still cannot achieve efficient charge transfer, proving that the two-step treatment synergistically optimizes the electron transport and catalytic kinetics performance of the material.

[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a nickel-molybdenum composite electrode material, characterized in that, include: Nickel salt, molybdenum salt and organic ligand were dissolved in deionized water to obtain homogeneous solutions. The homogeneous solution was mixed and stirred, and the reaction produced a precipitate to obtain the NiMo-MOF precursor slurry. The NiMo-MOF precursor slurry was centrifuged, washed, and dried to obtain NiMo-MOF powder. NiMo-MOF powder was calcined in air and then cooled to obtain NiMoO4 powder material. NiMoO4 powder was mixed with conductive carbon and annealed in a hydrogen / argon mixed atmosphere. After cooling, a nickel-molybdenum composite electrode material was obtained.

2. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, Both nickel salts and molybdenum salts are one or more of chloride salts, nitrate salts, sulfate salts, acetate salts, and acetylacetone salts; The organic ligand is dimethylimidazole.

3. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, The molar ratio of nickel salt, molybdenum salt and organic ligand is 1:1:3, the reaction temperature is room temperature, and the reaction time is 50-80 h.

4. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, The centrifugation speed is 3000~8000 rpm, the centrifugation time is 5~15 min, and the drying temperature is 60~80 ℃.

5. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, The washing process involves alternating between deionized water and ethanol, washing 2-5 times each.

6. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, During the calcination process, the calcination temperature is 400~700 ℃, the holding time is 2 h, and the heating rate is 1~5 ℃·min. -1 .

7. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, The conductive carbon is one or more of acetylene black, carbon nanotubes, and graphene. The mass of conductive carbon is 10 wt% to 40 wt% of the mass of NiMoO4 powder material.

8. The method for preparing the nickel-molybdenum composite electrode material according to claim 1, characterized in that, During the annealing process, the annealing temperature is 300~600 ℃, the holding time is 2 h, and the heating rate is 1~5 ℃·min. -1 .

9. A nickel-molybdenum composite electrode material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the nickel-molybdenum composite electrode material according to claim 9 in the preparation of water electrolysis devices for alkaline electrolyte systems.

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