A porous nickel-molybdenum alloy catalytic electrode for hydrogen production by electrolysis of water and a manufacturing method thereof

Abstract

This invention relates to a porous nickel-molybdenum alloy catalytic electrode for hydrogen production via water electrolysis and its fabrication method. The electrode comprises a nickel substrate providing support and conductivity, and a catalytically active layer supported thereon. The catalytically active layer is a porous nickel-molybdenum alloy containing a sacrificial metal. The nickel substrate and the catalytically active layer are integrally formed, self-supporting structures. The fabrication process employs a two-step alloying and a final dealloying method. The alloying process involves surface alloying to form an alloy on the nickel substrate surface, including mechanical energy-assisted infiltration, embedding, surface chemical vapor deposition, and electrodeposition. The dealloying process employs either gas-phase or liquid-phase dealloying. Compared to existing technologies, the porous alloy catalytic electrode provided by this invention, when applied to the cathode of water electrolysis for hydrogen production, exhibits high hydrogen evolution reaction activity, stable performance, and a simple and efficient fabrication method, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of materials technology for hydrogen production by water electrolysis, and in particular to a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis and its manufacturing method. Background Technology

[0002] Traditional fossil fuels are characterized by non-renewability, high pollution, and high carbon emissions. Currently, carbon reduction and emission reduction in the energy sector is an important trend for future development. Hydrogen energy has the characteristics of high calorific value and cleanliness. Utilizing water electrolysis technology to produce hydrogen can convert excess upstream wind and solar green electricity into green hydrogen, which can be applied to downstream transportation and metallurgical fields that are difficult to electrify, such as heavy trucks, long-range drones, and hydrogen metallurgy. It can also replace the gray hydrogen produced from traditional fossil fuels for the synthesis of green fuels such as ammonia and methanol for use in ocean-going vessels, and as a chemical raw material for the production of olefins, fertilizers, and many other chemical products. These applications replace a large portion of the consumption of oil, coal, and natural gas. Especially given the current energy situation of oil and gas shortages, this not only reduces a significant amount of carbon emissions but also enhances national energy security.

[0003] In the field of hydrogen production through water electrolysis, the performance of the catalytic electrode directly affects the electrolysis efficiency and stability. Currently, the cathode catalysts for hydrogen production through water electrolysis on the market mainly use Raney nickel, which involves thermally spraying an external layer of metal powder such as aluminum, nickel, and molybdenum onto a substrate. After a corrosion reaction, a porous structure is obtained. However, under high current, the overpotential for hydrogen evolution reaction is still too high, resulting in high energy consumption and high electricity costs, and the performance is not stable enough. On the other hand, using some precious metal catalysts such as platinum and ruthenium can reduce the overpotential, but their cost is high, which is not conducive to large-scale industrial applications.

[0004] In existing technologies, such as CN119913551A, a nanoporous composite electrocatalytic material is disclosed. By combining an electroplated alloy catalyst layer and a nanoporous structure layer, the bonding strength and structural stability of the electrode are improved. Simultaneously, the number of active sites for the hydrogen evolution reaction (HER) is increased, and the energy barrier of the HER kinetics is lowered, thereby effectively reducing the overpotential of the HER reaction. However, the preparation process of this electrode is relatively complex and costly, limiting its feasibility for industrial application.

[0005] Patent CN114318393A discloses a method for preparing a porous nickel-molybdenum-cobalt hydrogen evolution electrode. Through electrochemical corrosion and subsequent metal-organic coating, a porous structure is formed, improving the electrode's specific surface area and stability. However, the multi-step chemical processing involved in this method, including alkali degreasing and acid activation pretreatment, increases the preparation cost and process complexity. Furthermore, the electrode preparation efficiency is relatively low, making it difficult to meet the needs of large-scale industrial production.

[0006] In summary, although existing catalytic electrodes have made some progress in improving the activity and stability of the hydrogen evolution reaction, they still have shortcomings in terms of stable operation under high industrial current, preparation efficiency, cost control, and large-scale industrial application. Summary of the Invention

[0007] The purpose of this invention is to solve at least one of the above-mentioned problems by providing a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis and its manufacturing method. This porous nickel-molybdenum alloy catalytic electrode can operate stably under high industrial current, has low energy consumption, and can meet the requirements of large-scale mass production of catalysts, which is essential for promoting the development of the hydrogen energy industry.

[0008] The objective of this invention can be achieved through the following technical solution: a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis, comprising a nickel substrate layer providing support and conductivity, and a catalytic active layer supported thereon, wherein the catalytic active layer is a porous nickel-molybdenum alloy containing a sacrificial metal. The nickel substrate layer and the catalytic active layer supported thereon are integrally formed self-supporting structures.

[0009] Furthermore, the catalytic active layer is made of a nickel-molybdenum alloy, comprising two basic metal elements, nickel and molybdenum, and one or more sacrificial metals such as zinc, aluminum, manganese, magnesium, and copper. The mass fraction of the sacrificial metal element is 3% to 50%, preferably 5% to 20%, the mass fraction of molybdenum element is 3% to 50%, preferably 5% to 20%, and the balance is nickel.

[0010] Furthermore, the thickness of the catalytic active layer is 2~40μm, preferably 5~20μm, the catalytic active layer has a porous structure, the pore diameter is between 50nm and 10μm, preferably 100nm and 1μm, and the ligament size ranges from 50nm to 10μm, preferably 100nm and 1μm.

[0011] Further, the nickel substrate layer is metallic nickel or a nickel alloy, and its shape is mesh, foam, felt, or other nickel material with a mesh-like structure. If it is a nickel mesh, the mesh size of the nickel mesh substrate layer is 10-110 mesh, preferably 30-100 mesh, and the wire diameter is 150μm-350μm, preferably 200μm-300μm. If it is a foamed nickel substrate, the pore size of the foamed nickel substrate is between 5μm and 500μm, preferably 50μm-100μm, and the ligament size ranges from 5μm to 500μm, preferably 10μm-50μm. If it is a nickel felt substrate, the pore size formed by the nickel felt substrate is between 5μm and 500μm, preferably 30μm-60μm, and the fiber diameter ranges from 5μm to 500μm, preferably 10μm-50μm.

[0012] This invention also provides a method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis. The method employs a two-step alloying and a one-step dealloying process. The alloying process utilizes mechanical energy-assisted infiltration or embedding methods for thermal diffusion of metal powder. The dealloying process employs gas-phase dealloying or liquid-phase dealloying. Specifically, the method includes the following steps: S1. The nickel substrate is alloyed by incorporating active molybdenum elements into the nickel substrate to form a surface nickel-molybdenum alloy layer supported by the nickel substrate layer. S2. The nickel-molybdenum alloy mesh obtained in step S1 is alloyed by incorporating sacrificial metal elements to form a ternary nickel-based alloy layer. S3. The ternary nickel-based alloy supported by the nickel substrate obtained in step S2 is de-alloyed in the gas phase or liquid phase to form a catalytic active layer with a porous structure on the surface, thereby obtaining a catalytic electrode.

[0013] Furthermore, the alloying modification process in step S1 includes the following steps: S11. Add molybdenum metal powder to the filler and the penetration catalyst and mix them evenly to form a mixed powder, and put it into a reactor (such as a crucible) together with the nickel substrate; S12. Place the reactor into a heat treatment furnace with a rotating function and introduce protective gas; S13. Turn on the heat treatment furnace and anneal it at 500~1100℃ for 0.5~8 hours, while mechanical energy infiltration is carried out at a speed of 5~30 revolutions per minute to form the surface nickel-molybdenum alloy layer supported by the nickel base layer.

[0014] Furthermore, the molybdenum metal powder has a particle size of 1~50μm, the filler is alumina or silica powder particles, and the penetration catalyst is an active substance such as ammonium chloride, ammonium fluoride, or cerium dioxide. In the mixed powder, the mass fraction of the molybdenum metal powder is 30% to 90%, and the mass fraction of the penetration enhancer is 0% to 5%.

[0015] The protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon.

[0016] Furthermore, the alloying modification process in step S2 can be a thermal diffusion method, or a surface alloying method such as mechanical energy-assisted diffusion or chemical vapor deposition; if it is a thermal diffusion method, it includes the following steps: S21. Place the nickel-based nickel-molybdenum alloy obtained in step S1 into a reactor (the reactor can be a crucible or a ceramic boat, etc.), add sacrificial metal powder and filler, mix evenly, and cover the nickel-based nickel-molybdenum alloy. S22. Place the reactor in a heat treatment furnace and introduce protective gas; S23. Turn on the heat treatment furnace and anneal it at 380~1100℃ for 0.5~8 hours to form a ternary nickel-based alloy layer containing molybdenum and sacrificial metal elements.

[0017] Further, the filler is alumina or silica powder particles; in the mixed powder of sacrificial metal powder and filler, the mass fraction of the sacrificial metal powder is 30% to 90%, and the protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon; When using the mechanical energy-assisted infiltration method, the heat treatment furnace is controlled to rotate at a speed of 5 to 30 revolutions per minute; Other methods, such as thermal diffusion or surface chemical vapor deposition, do not require rotation.

[0018] Furthermore, in step S3, The specific steps of the vapor-phase dealloying method are as follows: the ternary nickel-based alloy is placed in a vacuum device and heated to a vacuum degree of less than 20 Pa, and kept at 450~850℃ for 0.5~5 h to form a catalytic active layer with a porous structure on the surface, thereby obtaining a catalytic electrode; The specific steps of liquid-phase dealloying are as follows: the ternary nickel-based alloy is placed in a reactor, and a corrosive solution with a concentration of 0.5~10M is added. The sacrificial metal component is selectively corroded and dissolved at 0~90℃. After 0.5~24 hours, a catalytic active layer with a porous structure is formed on the surface, and a catalytic electrode is obtained. The corrosive solution is one or more of the following corrosive solutions: potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonium sulfate, ammonium chloride, hydrochloric acid, dilute sulfuric acid, etc.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention benefits from the addition of an appropriate proportion of active molybdenum element to form a nickel-molybdenum alloy, which regulates the electronic structure and makes the hydrogen adsorption and desorption processes more balanced. This results in a lower overpotential for the hydrogen evolution reaction, which means that the current energy consumption required to produce a standard cubic meter of hydrogen is lower when operating under high current. Since 70% of the cost of hydrogen production by water electrolysis is electricity cost, this helps to reduce the cost of production and operation, thereby promoting its application.

[0020] 2. Higher stability. Unlike Raney nickel, where the catalytic active material is applied externally, this invention performs alloying and dealloying processes on the initial nickel substrate surface to ultimately form a self-supporting integrated nickel substrate layer and catalytic active layer. This effectively facilitates electron conduction, thereby reducing the resistance to the hydrogen evolution reaction. Furthermore, compared to externally applied materials, the connection between the catalytic active layer and the supporting substrate layer is stronger, making it less prone to detachment and thus reducing stability.

[0021] 3. The preparation process of this invention is simple, and the operation steps are suitable for large-scale industrial production. Molybdenum, as a refractory metal, requires alloying with a nickel substrate. Traditional methods typically involve alloy melting, wire drawing, and web formation, but these methods are energy-intensive. Furthermore, nickel-molybdenum alloys of a certain proportion are difficult to draw and form into a web, and the molybdenum ratio is difficult to adjust flexibly after web formation. Most importantly, replacing the entire nickel substrate with a certain proportion of nickel-molybdenum alloy consumes significantly more molybdenum metal than simply forming a nickel-molybdenum alloy on the surface of the nickel substrate, leading to a substantial increase in cost. External spraying or glow discharge plasma infiltration methods either result in weak bonding or are too inefficient for industrial mass production. This invention cleverly utilizes a mechanical energy-assisted infiltration method for the alloying process, reducing the temperature and time required for alloying the difficult-to-infiltrate molybdenum metal to a level suitable for industrial production. Subsequent secondary alloying and dealloying processes also meet the conditions for industrial application. Attached Figure Description

[0022] Figure 1 The above are cross-sectional surface scan EDS spectra of the nickel-molybdenum alloy layer after the first step of alloying modification of the nickel mesh substrate layer provided in Embodiments 1 and 2 of the present invention. Figure 2 Line scanned EDS spectra of the nickel-molybdenum alloy layer after the first alloying modification of the nickel mesh substrate layer provided in Examples 1 and 2 of this invention. Figure 3 This is a cross-sectional surface scan EDS energy spectrum of the ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer provided in Example 1 of the present invention undergoes a second alloying step. Figure 4 This is a magnified EDS energy spectrum of a cross-section of a ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer in Example 1 of the present invention undergoes a second alloying step. Figure 5 Line scan EDS spectrum of the ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer provided in Example 1 of the present invention undergoes a second alloying step. Figure 6 This is a scanning electron microscope image of the surface morphology of the catalytic active layer after liquid-phase dealloying, provided in Example 1 of the present invention. Figure 7 The electrochemical hydrogen evolution performance curve provided in Example 1 of the present invention.

[0023] Figure 8 This is a cross-sectional surface scan EDS energy spectrum of the ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer in Example 2 of the present invention undergoes a second alloying step. Figure 9 This is a magnified EDS energy spectrum of a cross-section of a ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer in Example 2 of the present invention undergoes a second alloying step. Figure 10Line scan EDS spectrum of the ternary nickel-based alloy layer formed after the nickel-molybdenum alloy layer in Example 2 of the present invention after the second alloying step; Figure 11 This is a surface scan EDS spectrum of the catalytic active layer after liquid-phase dealloying provided in Example 2 of the present invention. Figure 12 This is a scanning electron microscope image of the porous structure morphology of the catalytic active layer after liquid-phase dealloying, provided in Example 2 of the present invention. Figure 13 The electrochemical hydrogen evolution stability test diagram is provided for Example 2 of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0025] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, each point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value, or combined with other lower or upper limits, to form a range not explicitly stated. In the description of this application, it should be noted that, unless otherwise stated, "above" includes the stated number, and "multiple" in "one or more" means two or more.

[0026] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0027] Numerous details are explored in the following description to provide a more thorough explanation of embodiments of this application; however, it will be apparent to those skilled in the art that embodiments of this application may be practiced without these specific details.

[0028] The cathodic hydrogen evolution reaction in water electrolysis for hydrogen production can be broken down into Volmer and Tafel or Heyrovsky steps. Its overall key hydrogen evolution performance is critically influenced by the hydrogen adsorption free energy ΔGH. Generally, when designing catalysts, adjusting ΔGH ≈ 0 eV yields better catalytic performance. This requires alloying with other metals on pure nickel to modulate the electronic structure of nickel. Traditional methods, such as adding precious metals like platinum and ruthenium, can significantly improve catalytic performance, but they substantially increase manufacturing costs, hindering large-scale application. Besides selecting suitable active metal elements, a high specific surface area morphology is also needed to provide sufficient catalytic active sites for the reaction. Furthermore, during the cathodic hydrogen evolution reaction, hydrogen bubbles are continuously generated, constantly impacting the surface structure of the catalytic active layer, leading to mechanical fatigue or impact fracture at the bonding sites, affecting catalyst stability.

[0029] Therefore, in order to meet the requirements of "regulating hydrogen adsorption free energy, providing sufficient reactive sites, and maintaining catalytic stability", it is urgent to design a cathode catalyst that "contains highly catalytically active metal components, has a high specific surface area structure, and has strong mechanical connections".

[0030] Based on the above requirements, the present invention provides a self-supporting integrated porous nickel-molybdenum alloy catalytic electrode. This porous nickel-molybdenum alloy catalytic electrode includes a nickel substrate layer providing support and conductivity, and a catalytic active layer supported thereon. The catalytic active layer has a porous structure and is made of a nickel-molybdenum alloy containing molybdenum and other trace metal elements.

[0031] Preferably, the nickel substrate is a mesh, foam, or felt.

[0032] Preferably, the nickel substrate is metallic nickel or a nickel alloy. The nickel substrate is not limited to pure nickel, and may also contain one or more other metallic elements. Its function is not limited to support and conductivity; only its main functions are listed. It also has certain catalytic or other functions.

[0033] Preferably, if it is a nickel mesh, the mesh count of the nickel mesh substrate is 10 to 110 mesh, and the wire diameter is 150 μm to 350 μm. This invention does not specifically limit the mesh count and wire diameter of the nickel mesh. As one embodiment, the mesh count of the nickel mesh substrate can be 30, 50, 80, or 100 mesh, and the wire diameter can be 200 μm, 250 μm, or 300 μm.

[0034] The catalytic active layer is loaded on a nickel substrate in a self-supporting, integrated manner. It is formed by self-dissolution and "subtraction" rather than by external coating. This structural method satisfies the requirement of strong mechanical connection to a certain extent, which is beneficial to improving its operational stability.

[0035] The catalytic active layer is a nickel-molybdenum alloy containing molybdenum and other trace metals. This "nickel-molybdenum alloy" designation doesn't solely refer to an alloy composed of nickel and molybdenum; it may also include alloying elements from the original non-pure nickel substrate and sacrificial metals such as zinc, aluminum, manganese, and magnesium introduced during the second alloying process. These sacrificial metals primarily contribute to the porous structure of the nickel-molybdenum alloy layer through the alloying and dealloying process, but their catalytic effect is undeniable. The addition of molybdenum modulates the nickel's electronic structure, thereby adjusting the hydrogen adsorption free energy and enhancing hydrogen evolution performance.

[0036] Preferably, the catalytic active layer is made of a nickel-molybdenum alloy, comprising two basic metallic elements, nickel and molybdenum, and one or more sacrificial metals such as zinc, aluminum, manganese, magnesium, and copper. The mass fraction of molybdenum is between 3% and 50%, and the mass fraction of the sacrificial metal is between 3% and 50%.

[0037] This invention does not limit the specific elements of the nickel-molybdenum alloy, as long as it contains at least nickel and molybdenum. As one embodiment, other metallic elements may include one or more sacrificial metals such as zinc, aluminum, manganese, magnesium, and copper. This invention does not specifically limit the mass fraction of molybdenum; as one embodiment, the mass fraction may be 5%, 10%, 15%, 20%, etc. This invention also does not specifically limit the mass fraction of the sacrificial metal; as one embodiment, the aforementioned mass fraction may be 5%, 10%, 15%, 20%, etc.

[0038] The presence of a porous structure in the catalytic active layer does not mean that the entire catalytic active layer is porous. That is, the depth of the porous layer can completely cover or even exceed the nickel-molybdenum alloy layer, or it can only reach a partial depth, leaving parts of the nickel-molybdenum alloy layer unporosified. In short, the larger of the maximum depth of the nickel-molybdenum alloy layer and the maximum depth of the porous layer is used as the starting point of the catalytic active layer. The porous structure provides a sufficient number of active sites for the hydrogen evolution reaction, which is beneficial for improving catalytic performance.

[0039] Preferably, the catalytic active layer comprises a porous structure with pore diameters between 50 nm and 10 μm and ligament sizes ranging from 50 nm to 10 μm. This invention does not specifically limit the pore diameter and ligament size of the porous structure; as an example, the pore diameter can be 100 nm, 500 nm, 1 μm, etc., and the ligament size can be 100 nm, 500 nm, 1 μm, etc.

[0040] Preferably, the thickness of the catalytic active layer is between 2 and 40 μm. This invention does not specifically limit the thickness of the catalytic active layer; as an example, the specific thickness can be 5 μm, 10 μm, 20 μm, etc.

[0041] Therefore, the porous nickel-molybdenum alloy catalytic electrode possesses the necessary conditions of "containing highly catalytically active metal components, high specific surface area structure, and strong mechanical connection." However, the fabrication process of this type of catalytic electrode requires overcoming significant difficulties. One notable challenge is how to incorporate high-melting-point molybdenum into a nickel substrate in a low-energy-consumption and cost-effective manner to form an alloy. Currently, the mainstream approach in the market involves mixing nickel, molybdenum, and aluminum powders in a specific ratio, thermally spraying them onto the surface of a nickel substrate, where they adhere or melt, and then dissolving the active metal components through a chemical reaction to form a porous structure. However, this method also has certain drawbacks. The catalytically active material of the electrode is essentially added from the outside rather than being self-supporting and integrated. Under prolonged impact from hydrogen bubbles or intense hydrogen evolution reactions at high current densities, it is prone to detachment, leading to a decline in performance. There is also a method of directly producing nickel-molybdenum alloy mesh by melting nickel-molybdenum alloy and spinning and drawing wire to form a mesh. However, it is difficult to draw and form a mesh under a certain molybdenum content ratio. Moreover, the molybdenum ratio cannot be flexibly adjusted as needed after the mesh is formed. Most importantly, replacing the entire nickel substrate material with a certain proportion of nickel-molybdenum alloy consumes a large amount of molybdenum metal compared to simply forming a nickel-molybdenum alloy on the surface of the nickel substrate, which leads to a significant increase in cost.

[0042] To solve the above-mentioned preparation problems, this invention ingeniously utilizes a mechanical energy-assisted infiltration method for the alloying process, reducing the temperature and time of the difficult-to-infiltrate molybdenum metal alloying process to a level that can be industrialized. The subsequent secondary alloying and dealloying processes also meet the conditions for industrial application.

[0043] Specifically, the fabrication process of this catalytic electrode employs a two-step alloying and a final dealloying method. The alloying process utilizes surface alloying techniques to form an alloy on the nickel substrate surface, including mechanical energy-assisted infiltration, embedding methods, surface chemical vapor deposition, and electrodeposition. The dealloying process employs either vapor-phase or liquid-phase dealloying. The specific steps include: S1. Alloying the nickel substrate by incorporating active molybdenum into the nickel substrate to form a surface nickel-molybdenum alloy layer supported by the nickel substrate layer; specifically including the following steps: S11. Molybdenum metal powder is added to filler and penetration catalyst and mixed evenly to form a mixed powder, which is then placed in a crucible together with the nickel substrate; the particle size of the molybdenum metal powder is 1~50μm, and the mass fraction of the molybdenum metal powder in the mixed powder is 30%~90%; preferably, the mass fraction can be 30%, 50%, 80%, etc. This invention does not limit the specific types of fillers and penetration enhancers in the mixed powder. As a specific embodiment, the filler can be powder particles such as alumina or silica; the penetration enhancer can be ammonium chloride, ammonium fluoride, cerium oxide, etc. The particle size of the filler can be 40 mesh to 325 mesh.

[0044] The present invention does not specifically limit the particle size of the molybdenum powder. As an example, the particle size can be 3μm, 5μm, 10μm, etc.

[0045] S12. Place the crucible into a heat treatment furnace with a rotating function and introduce a protective gas; the protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon; S13. The heat treatment furnace is turned on for 0.5 to 8 hours and held at a temperature of 500 to 1100°C for annealing. A certain rotation speed is set for mechanical energy infiltration (rotation speed is 5 to 30 revolutions per minute). After the time is up, a nickel-molybdenum alloy layer supported by a nickel base layer is formed on the surface.

[0046] The present invention does not specifically limit the temperature and time for heating the sample in the heat treatment furnace. As one embodiment, the temperature can be 800℃, 900℃, 1000℃, etc., and the time can be 1h, 3h, 5h, etc.

[0047] The present invention does not specifically limit the mechanical energy application method for the mechanical energy-assisted infiltration. A heat treatment furnace with a rotation function is preferred. However, the present invention is not limited to this rotational application method of mechanical energy, and it can also be in the form of vibration energy, ultrasonic energy, etc.

[0048] As one embodiment, the rotation speed of the heat treatment furnace with rotation function described in this invention is between 5 and 30 revolutions per minute. Specifically, the selected rotation speed can be 7, 10, 15, 20 revolutions per minute, etc.

[0049] S2. The nickel-molybdenum alloy supported by the nickel substrate obtained in step S1 is incorporated into the surface nickel-molybdenum alloy layer by alloying with sacrificial metal elements to form a ternary nickel-based alloy layer. The alloying modification can be achieved through thermal diffusion, or surface alloying methods such as mechanical energy-assisted diffusion or chemical vapor deposition. If thermal diffusion is used, the following steps are included: S21. Place the nickel-based nickel-molybdenum alloy obtained in step S1 in a ceramic boat, add sacrificial metal powder and filler, mix evenly, and cover the nickel-based nickel-molybdenum alloy. This invention does not specifically limit the sacrificial metal powder and filler. As one embodiment, the sacrificial metal powder can be zinc, aluminum, manganese, magnesium, copper, or other metal powders, as long as they can produce corresponding alloying and dealloying to form functional pores. The filler can be alumina or silicon dioxide powder particles. Preferably, the sacrificial metal element is one or more of zinc, aluminum, manganese, magnesium, and copper. This invention does not specifically limit the ratio of the sacrificial metal and filler. Preferably, the mass fraction of the sacrificial metal powder in the mixed powder of sacrificial metal powder and filler is 30% to 100%. As one embodiment, its mass fraction percentage can be 30%, 50%, 80%, etc. The filler is alumina or silicon dioxide powder particles.

[0050] S22. Place the ceramic boat in a heat treatment furnace and introduce a protective gas; the protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon; as an example, the specific protective gas can be nitrogen, argon, hydrogen, etc.

[0051] The ceramic boat described in this invention is merely a name for a crucible and is not limited to a specific type of ceramic boat; other containers capable of performing the corresponding function can also be used. As one embodiment, the container can be a ceramic crucible, an iron or steel crucible container, a glass crucible, etc.

[0052] S23. Turn on the heat treatment furnace and anneal it at 380~1100℃ for 0.5~8 hours. If mechanical energy-assisted infiltration is used, a rotation function is set, with a rotation speed of 5~30 revolutions per minute. If other methods such as ordinary embedding, surface chemical vapor deposition, or electrodeposition are used, rotation is not required. After the time is up, a ternary nickel-based alloy layer containing molybdenum and sacrificial metal elements is formed. As one embodiment, the specific time for the heat treatment can be 1 hour, 3 hours, 5 hours, etc., and the specific temperature can be 380℃, 500℃, 800℃, etc., which can be determined by the type of sacrificial metal element and the thickness of the infiltrated layer to be infiltrated.

[0053] In this step, the nickel-molybdenum alloy supported by the nickel substrate after the first step is further alloyed by adding sacrificial metal powder and filler in a heat treatment furnace. Mechanical energy infiltration can be used, or other methods such as ordinary embedding, surface chemical vapor deposition, and electrodeposition can be used. After annealing at a certain time and temperature, a ternary nickel-based alloy layer containing molybdenum and sacrificial metal elements is formed.

[0054] S3. The ternary nickel-based alloy layer obtained in step S2 is disposed in the gas phase or liquid phase to form the catalytic active layer with the porous structure on the surface, thereby obtaining the catalytic electrode.

[0055] Preferably, in step S3: After the nickel substrate-supported ternary nickel-based alloy undergoing step S2 is cleaned in deionized water, it is then subjected to gas-phase or liquid-phase dealloying.

[0056] If it is a vapor-phase dealloying process, the ternary nickel-based alloy is placed in a vacuum device and heated, and held at a certain vacuum level for a certain time to form the catalytic active layer with the porous structure on its surface, thus obtaining the catalytic electrode. Preferably, the vacuum level during heating in the vacuum device is lower than 20 Pa, the holding temperature is 450~850℃, and the holding time is 0.5~5h.

[0057] If liquid-phase dealloying is used, the ternary nickel-based alloy is placed in a beaker, and a solution of a certain concentration is added. The sacrificial metal component is selectively corroded and dissolved at a certain temperature. After a period of time, a catalytic active layer with the porous structure is formed on its surface, thus obtaining the catalytic electrode. Preferably, the solution is one of the following corrosive solutions: potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonium sulfate, ammonium chloride, hydrochloric acid, or dilute sulfuric acid; the concentration of the solution is between 0.5 and 10 M; the corrosion and dissolution time is between 0.5 and 24 hours; and the corrosion and dissolution temperature is between 0 and 90°C.

[0058] In step S3 of this invention, the ternary nickel-based alloy obtained in step S2 is subjected to gas-phase or liquid-phase dealloying to form a catalytic active layer with a porous structure on its surface, thereby obtaining a catalytic electrode. Specifically, if gas-phase dealloying is used, the alloy is placed in a vacuum chamber and heated, and held at a certain vacuum level for a certain period of time to form the catalytic active layer with a porous structure on its surface, thus obtaining the catalytic electrode. If liquid-phase dealloying is used, the ternary nickel-based alloy is placed in a beaker, and a solution of a certain concentration is added to selectively corrode and dissolve its sacrificial metal component at a certain temperature. After a period of time, the catalytic active layer with a porous structure on its surface is formed, thus obtaining the catalytic electrode.

[0059] This invention does not specifically limit the vacuum equipment for vapor-phase dealloying; it only requires a vacuum level below 20 Pa and equipment with heating and heat preservation functions. Samples can be placed in the equipment using containers such as crucibles. As one embodiment, the vacuum level can be 0.1 Pa, 1 Pa, 5 Pa, or 10 Pa, depending on the required pore and ligament sizes.

[0060] Furthermore, the heat preservation temperature is 450~850℃, and the heat preservation time is between 0.5~5 hours. This invention does not specifically limit the specific heat preservation temperature and time, but depends on whether successful perforation is possible and the required hole and ligament sizes. As one embodiment, the heat preservation temperature can be 500℃, 600℃, or 700℃, and the heat preservation time can be 1 hour, 1 hour, 3 hours, etc.

[0061] This invention does not specifically limit the type of solution for liquid-phase dealloying, as long as it can selectively react and dissolve the corresponding sacrificial metal element. Specifically, as an example, the solution is one of the following corrosive liquids: potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonium sulfate, ammonium chloride, hydrochloric acid, dilute sulfuric acid, etc.

[0062] The present invention does not specifically limit the solution concentration for liquid-phase dealloying, but determines it according to the size of the pores to be dissolved and the proportion of sacrificial metal elements left behind. As an example, the solution concentration can be 1M, 2M, 5M, etc.

[0063] This invention does not specify the dissolution time and temperature for liquid-phase dealloying, nor does it require a certain degree of dissolution of the sacrificial metal. It can dissolve completely or leave a portion, depending on the size of the pores to be dissolved and the proportion of the sacrificial metal element remaining. As an example, the specific dissolution time can be 1 hour, 5 hours, 15 hours, etc., and the specific dissolution temperature can be 10℃, 40℃, 90℃, etc.

[0064] Based on the above features and manufacturing steps, the porous nickel-molybdenum alloy catalytic electrode of this invention is applied to the cathode of water electrolysis for hydrogen production. It exhibits high hydrogen evolution reaction activity, stable performance, and a simple and efficient manufacturing method, making it suitable for large-scale industrial production.

[0065] To further understand the present invention, the following embodiments are provided. It is worth noting that, unless otherwise specified, all raw materials used in the present invention are commercially available; and all methods and equipment employed are common in the art.

[0066] Example 1 A porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis is prepared by the following method: Materials required: 50-mesh nickel mesh; approximately 5μm molybdenum powder; approximately 325-mesh zinc powder as the sacrificial metal; approximately 325-mesh alumina powder as the filler; ammonium chloride as the diffusion catalyst; and potassium hydroxide solution at approximately 6M concentration for liquid-phase dealloying. Experimental equipment included a rotating heat treatment furnace, ceramic crucibles, beakers, and a balance.

[0067] The specific fabrication method of the porous nickel-molybdenum alloy catalytic electrode in this embodiment includes the following steps: S1. Weigh the molybdenum powder, alumina powder, and ammonium chloride powder according to a mass fraction of 80%:18%:2%, and mix them evenly in a ceramic crucible.

[0068] S2. Place the nickel mesh into the mixed powder in the ceramic crucible, and place it under the coverage of the mixed powder.

[0069] S3. Place the ceramic crucible into a heat treatment furnace with a rotating function, and pre-introduce argon gas at a flow rate of 200 sccm for about 20 minutes.

[0070] S4. Set the heat treatment furnace to 800℃, 5-hour holding time, and 9 revolutions per minute rotation speed. Turn on the heating.

[0071] S5. After the heating and heat preservation process is completed, let it cool naturally to room temperature, and take out the crucible and the nickel mesh sample inside the crucible (at this time, the obtained nickel mesh sample is a nickel-molybdenum alloy mesh material with a surface nickel-molybdenum alloy layer supported by the nickel mesh base layer).

[0072] S6. Place the nickel-molybdenum alloy mesh into a beaker, add a certain amount of deionized water, and clean it in an ultrasonic cleaning tank for 5 minutes. Then remove it and let it air dry naturally.

[0073] Surface scan and line scan energy dispersive spectroscopy (EDS) analyses were performed on the cross-section of the obtained nickel-molybdenum alloy mesh, as shown in the figures. Figure 1-2 The image shown is an EDS spectrum of the nickel-molybdenum alloy layer after the first alloying modification of the nickel mesh substrate. Figure 1 As can be seen, molybdenum successfully penetrated from the surface of the nickel mesh to a depth of approximately 10 μm. Figure 2 It can be seen that the molybdenum content decreases from the surface to the core, with the highest content at the surface. This is a result of the chemical potential gradient driving the alloying process.

[0074] S7. Weigh the zinc powder and alumina powder according to a mass fraction of 70%:30%, put them into a crucible and mix them evenly.

[0075] S8. Place the nickel-molybdenum alloy mesh obtained in step S6 into the powder in the crucible, and place it under the coating of the mixed powder.

[0076] S9. Place the crucible in a conventional heat treatment furnace and pre-purge it with argon gas at a flow rate of 200 sccm for about 20 minutes.

[0077] S10. Set the heat treatment furnace to 400℃ and a holding time of 0.5 hours, then turn on the heating.

[0078] S11. After the heating and heat preservation process is completed, let it cool naturally to room temperature, and take out the crucible and the nickel mesh sample inside the crucible (at this time, the obtained nickel mesh sample forms a ternary nickel-based alloy mesh containing molybdenum and sacrificial metal elements).

[0079] S12. Place the ternary nickel-based alloy mesh into a beaker, add a certain amount of deionized water, and clean it in an ultrasonic cleaning tank for 5 minutes. Then remove it and let it air dry naturally.

[0080] The obtained ternary nickel-based alloy mesh cross-section was analyzed by surface scan and line scan energy dispersive spectroscopy, as shown in the figure. Figure 3-5 The image shows the cross-sectional EDS energy spectrum of the ternary nickel-based alloy layer formed after the second alloying step of the nickel-molybdenum alloy layer. Figure 3-5 As can be seen, zinc successfully penetrated from the surface of the nickel mesh to a depth of about 25μm, preparing for the subsequent dealloying process. At the same time, a certain amount of molybdenum enrichment was formed in the boundary area of ​​the zinc diffusion layer. This may be a result of the incompatibility between zinc as a sacrificial metal and molybdenum, allowing for the selection of a more suitable sacrificial metal.

[0081] S13. Place the cleaned ternary nickel-based alloy mesh in a beaker and add a 6M potassium hydroxide solution.

[0082] S14. Place the beaker in a fume hood at room temperature (25°C) to allow the sacrificial metal component zinc to dissolve naturally for 10 hours.

[0083] S15. After the time expires, the catalytic active layer with a porous structure on its surface is obtained, and the target catalytic electrode is obtained.

[0084] Figure 6 The image shown is a scanning electron microscope image of the surface morphology of the catalytic active layer after liquid-phase dealloying provided in this embodiment, which is the surface morphology of the catalytic electrode after step S15. It can be seen that there are cracks and gaps on the surface, and columnar crystalline nickel-molybdenum alloy can be seen in the cracks. There is a porous structure formed by dissolution, which will help improve the catalytic performance.

[0085] Comparative Example 1 Comparative Example 1 uses a porous nickel catalytic electrode without molybdenum doping. The materials and preparation process are the same as those of the porous nickel-molybdenum alloy electrode in Example 1, except that the molybdenum doping surface alloying process in steps S1 to S5 of Example 1 is omitted. The rest of the preparation steps and the materials used, such as the nickel substrate and the sacrificial metal element zinc, are the same. That is, the nickel mesh is directly placed into a beaker, a certain amount of deionized water is added, and it is cleaned in an ultrasonic cleaning tank for 5 minutes. It is then taken out and air-dried naturally. The rest is the same as steps S7 to S15 of Example 1.

[0086] Comparative Example 2 Comparative Example 2 selected a porous nickel-molybdenum-cobalt cathode catalyst prepared by electrodeposition using the published patent CN114318393A. This method also involves doping molybdenum onto the surface of a nickel substrate to form a porous nickel-molybdenum alloy. Five of the examples achieved a current of 100 mA / cm². 2 The overpotential values ​​at the given current densities were 153mV, 167mV, 182mV, 158mV, and 162mV, respectively.

[0087] The electrodes obtained in Example 1 and Comparative Examples 1-2 were subjected to performance testing, as follows: The catalyst meshes obtained in Example 1 and Comparative Example 1 were cut to a size of 1cm × 1cm. Using a Chenhua electrochemical workstation, a 1M KOH solution was selected as the electrolyte, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. Linear scanning voltammetry was performed on the three-electrode system. The applied potential range was from -0.8V to -1.4V, the current density test range was between 0 and -400mA, and the scan rate was 5mV / s. Before the test, the catalyst was activated to a stable state by performing about 20 cycles of cyclic voltammetry scans. Figure 7 The graphs show the electrochemical hydrogen evolution performance of Examples 1 and Comparative Example 1 of this invention, where the vertical axis represents current density and the horizontal axis represents potential value. It can be seen that the performance curve of the catalytic electrode prepared in Example 1 of this invention shows a significant improvement, reaching 400 mA / cm². 2 The absolute value of the potential at the given current density is 1.06V, minus 0.924V (the calculation method is shown in the following two lines of formulas). The calculated overpotential value was 136 mV, while the overpotential value of the porous nickel catalytic electrode in Comparative Example 1 was 256 mV at the same current density, indicating that the hydrogen evolution performance was significantly lower than that in Example 1.

[0088] The hydrogen evolution performance of the porous nickel-molybdenum-cobalt cathode catalysts obtained in Example 1 and Comparative Example 2 was compared. In Comparative Example 2, the electrode at 100 mA / cm²... 2The overpotential values ​​of the five samples measured at the given current density were 153mV, 167mV, 182mV, 158mV, and 162mV, respectively; while in this embodiment, the overpotential values ​​were measured at 100mA / cm². 2 The overpotential value at the current density is within 50mV, which is significantly lower than that of Comparative Example 2; even at 400mA / cm 2 The overpotential value at the current density was only 136mV, which is much lower than that at 100mA / cm in Comparative Example 2. 2 The overpotentials are all lower, meaning the catalytic activity is significantly higher than that of Comparative Example 2.

[0089] Example 2 A porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis is prepared by the following method: Materials: 50-mesh nickel mesh; approximately 5μm molybdenum powder; aluminum powder as the sacrificial metal, with a particle size between 5μm and 30μm; alumina powder as the filler, with a particle size of approximately 325 mesh; ammonium chloride as the catalyst; and potassium hydroxide solution at a concentration of approximately 6M for liquid-phase dealloying. Experimental equipment included a heat treatment furnace with a rotating function, a ceramic crucible, a sealed reaction vessel, beakers, a balance, and other instruments.

[0090] The specific fabrication method of the porous nickel-molybdenum alloy catalytic electrode in this embodiment includes the following steps: S1. Weigh the molybdenum powder, alumina powder, and ammonium chloride powder according to a mass fraction of 80%:18%:2%, and mix them evenly in a ceramic crucible.

[0091] S2. Place the nickel mesh into the mixed powder in the ceramic crucible, and place it under the coverage of the mixed powder.

[0092] S3. Place the ceramic crucible into a heat treatment furnace with a rotating function, and pre-introduce argon gas at a flow rate of 200 sccm for about 20 minutes.

[0093] S4. Set the heat treatment furnace to 800℃, 5-hour holding time, and 9 revolutions per minute rotation speed. Turn on the heating.

[0094] S5. After the heating and heat preservation process is completed, let it cool naturally to room temperature, and take out the crucible and the nickel mesh sample inside the crucible (at this time, the obtained nickel mesh sample is a nickel-molybdenum alloy mesh material with a surface nickel-molybdenum alloy layer supported by the nickel mesh base layer).

[0095] S6. Place the nickel-molybdenum alloy mesh into a beaker, add a certain amount of deionized water, and clean it in an ultrasonic cleaning tank for 5 minutes. Then remove it and let it air dry naturally.

[0096] Surface scan and line scan energy dispersive spectroscopy (EDS) analyses were performed on the cross-section of the obtained nickel-molybdenum alloy mesh, as shown in the figures. Figure 1-2The image shown is an EDS spectrum of the nickel-molybdenum alloy layer after the first alloying modification of the nickel mesh substrate. Figure 1 As can be seen, molybdenum successfully penetrated from the surface of the nickel mesh to a depth of approximately 10 μm. Figure 2 It can be seen that the molybdenum content decreases from the surface to the core, with the highest content at the surface. This is a result of the chemical potential gradient driving the alloying process.

[0097] S7. Weigh the aluminum powder, alumina powder, and ammonium chloride powder according to a mass fraction ratio of 49%:49%:2%, and put them into a sealed reaction container and mix them evenly.

[0098] S8. Place the nickel-molybdenum alloy mesh obtained in step S6 into the powder in a sealed reaction vessel. S9. Place the sealed reaction vessel into a conventional heat treatment furnace and pre-purge with argon gas at a flow rate of 200 sccm for about 20 minutes.

[0099] S10. Set the heat treatment furnace to 600℃ and maintain the temperature for 5 hours, then turn on the heating.

[0100] S11. After the heating and heat preservation process is completed, let it cool naturally to room temperature, and take out the sealed reaction vessel and the nickel mesh sample inside the vessel (at this time, the obtained nickel mesh sample forms a ternary nickel-based alloy mesh containing molybdenum and sacrificial metal elements).

[0101] S12. Place the ternary nickel-based alloy mesh into a beaker, add a certain amount of deionized water, and clean it in an ultrasonic cleaning tank for 5 minutes. Then remove it and let it air dry naturally.

[0102] The obtained ternary nickel-based alloy mesh cross-section was analyzed by surface scan and line scan energy dispersive spectroscopy, as shown in the figure. Figure 8-10 The image shows the cross-sectional EDS energy spectrum of the ternary nickel-based alloy layer formed after the second alloying step of the nickel-molybdenum alloy layer. Figure 8-10 As can be seen, aluminum successfully reacted on the surface of the nickel-molybdenum alloy mesh to form a Ni-Mo-Al alloy layer with a depth of about 30μm, which prepared the way for the subsequent dealloying process. At the same time, it can be observed that the use of aluminum solved the problem of immiscibility between zinc and molybdenum, and did not cause the segregation and enrichment of molybdenum.

[0103] S13. Place the cleaned ternary nickel-based alloy mesh in a beaker and add a 6M potassium hydroxide solution.

[0104] S14. Place the beaker in a fume hood at room temperature (25°C) to allow the sacrificial metal component zinc to dissolve naturally for 10 hours.

[0105] S15. After the time expires, the catalytic active layer with a porous structure on its surface is obtained, and the target catalytic electrode is obtained.

[0106] Figure 11 and Figure 12 The images shown are the surface energy spectrum scan and porous structure morphology of the catalytic active layer after liquid-phase dealloying obtained in Example 2 of this invention, which are the surface morphology of the catalytic electrode after step S15. It can be seen that there are cracks and gaps on the surface, and granular nickel-molybdenum alloy particles can be seen in the cracks. There is a porous structure formed by dissolution, which will help improve the catalytic performance.

[0107] Figure 12 To test the hydrogen evolution stability at industrial-grade current density in Example 2, an electrochemical workstation system from the Landian brand was used. The porous nickel-molybdenum alloy catalyst mesh obtained in Example 2 was cut to a size of 1cm × 1cm. A 1M KOH solution was selected as the electrolyte, Hg / HgO as the reference electrode, and the nickel mesh as the counter electrode. A constant current method stability test was performed on the three-electrode system. The applied current was 500mA in an industrial-grade alkaline electrolytic cell with a voltage range of -4 to 4V, and the test duration was 400 hours. The test results show that at 500mA / cm... 2 At the given current density, the overpotential is only around 150 mV, and the hydrogen evolution activity is comparable to that of the Ni-Mo-Zn catalyst in Example 1. After a test lasting 400 hours, the results are as follows: Figure 13 As shown, its hydrogen evolution activity shows no signs of decay and it has sufficient stability at high current densities.

[0108] This Example 2 also demonstrates the universality of the preparation method of the present invention, which can be extended to a variety of sacrificial metal elements and optimized.

[0109] As can be seen from the preparation processes of Examples 1 and 2, the highest temperature experienced during the preparation process is only 800℃, and the duration is 5 hours. This is within the range of mature technologies for industrial-grade heat treatment furnaces. It also eliminates the need to heat the nickel-molybdenum metal to its melting point of over 2600℃ to form the nickel-molybdenum alloy block, thus reducing energy consumption. In fact, by adjusting appropriate mechanical energy-assisted molybdenum infiltration process parameters, the temperature and time can be reduced even further to minimize energy consumption. Adding a micron-thickness layer of molybdenum only to the surface layer of the nickel substrate also significantly reduces molybdenum consumption and lowers costs. The nickel mesh, alumina, and molybdenum powder raw materials required for the remaining preparation steps are all industrially mature and widely used products. The raw materials, equipment, temperature, time, alkali solution, and gas conditions required for the surface alloying and sacrificial metal component incorporation and dealloying steps can also meet the requirements for industrial production. Therefore, this invention features stable operation under high industrial current, low energy consumption, and the ability to meet the needs of large-scale mass production.

[0110] The foregoing has shown and described the basic process, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis, characterized in that, It includes a nickel substrate layer that provides support and conductivity, and a catalytically active layer supported thereon, the catalytically active layer being a porous nickel-molybdenum alloy containing a sacrificial metal; The nickel substrate and the catalytic active layer supported thereon are an integrated self-supporting structure.

2. The porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 1, characterized in that, The nickel substrate is a nickel material with a mesh-like structure, including nickel mesh, nickel foam, or nickel felt.

3. The porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 1, characterized in that, The sacrificial metal element has a mass fraction of 3% to 50%, the molybdenum element has a mass fraction of 3% to 50%, and the balance is nickel; the sacrificial metal is one or more of zinc, aluminum, manganese, magnesium, and copper.

4. The porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 1, characterized in that, The thickness of the catalytic active layer is 2~40μm, the catalytic active layer has a porous structure with pore diameter between 50nm and 10μm, and the ligament size ranges from 50nm to 10μm.

5. A method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis as described in any one of claims 1-4, characterized in that, The method employs a two-step alloying and one-step dealloying process. The alloying process utilizes mechanical energy-assisted diffusion or embedding methods for thermal diffusion of the metal powder. The dealloying process employs either gas-phase or liquid-phase dealloying, and specifically includes the following steps: S1. The nickel substrate is alloyed by incorporating active molybdenum elements into the nickel substrate to form a surface nickel-molybdenum alloy layer supported by the nickel substrate layer. S2. The nickel-based nickel-molybdenum alloy (Ni / Ni-Mo) obtained in step S1 is alloyed by incorporating sacrificial metal elements to form a ternary nickel-based alloy layer (Ni / Ni-Mo-M) supported by a nickel substrate. S3. The ternary nickel-based alloy layer supported by the nickel substrate obtained in step S2 is de-alloyed in the gas phase or liquid phase to form a catalytic active layer with a porous structure on the surface, thereby obtaining a catalytic electrode.

6. The method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 5, characterized in that, The alloying modification process in step S1 includes the following steps: S11. Add molybdenum metal powder to filler and penetration catalyst and mix evenly to form mixed powder, and put it into the reactor together with the nickel substrate; S12. Place the reactor into a heat treatment furnace with a rotating function and introduce protective gas; S13. Turn on the heat treatment furnace and anneal it at 500~1100℃ for 0.5~8 hours, while mechanical energy infiltration is carried out at a speed of 5~30 revolutions per minute to form the surface nickel-molybdenum alloy layer supported by the nickel base layer.

7. The method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 6, characterized in that, The molybdenum metal powder has a particle size of 1~50μm, the filler is alumina or silica powder particles, and the penetration catalyst is ammonium chloride, ammonium fluoride or cerium oxide. In the mixed powder, the mass fraction of the molybdenum metal powder is 30%~90%, the mass fraction of the filler is 10%~30%, and the mass fraction of the penetration enhancer is 0%~5%. The protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon.

8. The method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 5, characterized in that, The alloying modification in step S2 includes thermal diffusion, mechanical energy-assisted diffusion, and chemical vapor phase alloying. The thermal diffusion process includes the following steps: S21. Place the nickel-based nickel-molybdenum alloy (Ni / Ni-Mo) obtained in step S1 into a reactor, add sacrificial metal powder and filler, mix evenly, and cover the Ni / Ni-Mo. S22. Place the reactor in a heat treatment furnace and introduce protective gas; S23. Turn on the heat treatment furnace and anneal it at 380~1100℃ for 0.5~8 hours to form a ternary nickel-based alloy layer containing molybdenum and sacrificial metal elements.

9. A method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 8, characterized in that, The filler is alumina or silica powder particles; in the mixed powder of sacrificial metal powder and filler, the mass fraction of the sacrificial metal powder is 30% to 100%, and the protective gas is one or more of nitrogen, hydrogen, argon, neon, helium, and xenon. When using the mechanical energy-assisted infiltration method, the heat treatment furnace is controlled to rotate at a speed of 5 to 30 revolutions per minute; If thermal diffusion or other surface alloying methods are used, rotation is not required.

10. The method for fabricating a porous nickel-molybdenum alloy catalytic electrode for hydrogen production by water electrolysis according to claim 5, characterized in that, In step S3, The specific steps of the vapor-phase dealloying method are as follows: the ternary nickel-based alloy (Ni / Ni-Mo-M) is placed in a vacuum device and heated to a vacuum degree of less than 20 Pa, and kept at 450~850℃ for 0.5~5h to form a catalytic active layer with a porous structure on the surface, thereby obtaining a catalytic electrode; The specific steps of liquid-phase dealloying are as follows: the ternary nickel-based alloy is placed in a reactor, and a 0.5-10M etchant is added. The sacrificial metal components are selectively etched and dissolved at 0-90°C. After 0.5-24 hours, a catalytic active layer with a porous structure is formed on the surface, and a catalytic electrode is obtained. The etchant is one of potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonium sulfate, ammonium chloride, hydrochloric acid, or dilute sulfuric acid.

Images