Alkaline hydrogen production electrode and method of making same

Abstract

The application belongs to the field of electrode materials, and particularly relates to an alkaline hydrogen production electrode and a preparation method thereof. The alkaline hydrogen production electrode comprises an electrode substrate and a catalyst loaded on the electrode substrate; the catalyst comprises the following components: Ni, Fe, Mo, Cr and Mn, wherein the molar percentage of Mo is 5-15%, and the total molar percentage of Fe and Mo is 35%. Through alloying and the introduction of Mo, and the control of the content of Fe and Mo, the catalytic activity is enhanced, the catalytic activity is higher compared with existing binary Raney nickel, the HER reaction overpotential can be effectively reduced, thereby the energy consumption of an electrolytic cell is reduced, and Cr and Mn can enhance the corrosion resistance of the electrode.

Description

Technical Field

[0001] This application belongs to the field of electrode materials, specifically relating to an alkaline hydrogen production electrode and its preparation method. Background Technology

[0002] With the rapid growth of installed capacity of new energy sources such as wind and solar power, the importance of new energy power consumption has become increasingly prominent. Hydrogen, as an important chemical raw material and energy carrier, currently relies heavily on methods that generate significant carbon emissions, such as coal-to-hydrogen and chemical by-product hydrogen production. Green electricity-to-hydrogen production can address both of these issues simultaneously. Currently, the mainstream green hydrogen production method is water electrolysis. Unlike the stable operation of traditional electrolyzers, green electricity-to-hydrogen production is highly volatile, requiring the electrolyzer to operate with the source of the load. However, frequent start-ups and shutdowns, as well as fluctuations in operating conditions, are detrimental to the electrodes, which directly affect the performance of the electrolyzer. The reverse current caused by the start-up and shutdown of the electrolyzer leads to rapid electrode degradation, making it difficult to meet the demands of large-scale hydrogen production.

[0003] Currently, the electrodes used in alkaline water electrolysis for hydrogen production are mainly nickel-aluminum binary catalysts. However, the performance of nickel-aluminum binary catalysts is no longer sufficient to meet the increasing performance requirements of electrolyzers. Meanwhile, multi-element alloy electrodes, such as nickel-molybdenum-aluminum ternary electrodes, experience rapid performance degradation due to issues like intermetallic potential corrosion.

[0004] In summary, existing alkaline water electrolysis hydrogen production electrode materials still have significant shortcomings in dealing with complex operating conditions such as fluctuations in green electricity, frequent start-stop cycles, and reverse current. There is an urgent need to develop a new type of electrode material that combines high catalytic activity and excellent electrochemical stability to meet the needs of the large-scale development of green electricity hydrogen production technology. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide an alkaline hydrogen production electrode and its preparation method, which has both high catalytic activity and excellent electrochemical stability.

[0006] In a first aspect, this application provides an alkaline hydrogen production electrode, comprising: an electrode substrate and a catalyst supported on the electrode substrate;

[0007] The catalyst comprises the following components: Ni, Fe, Mo, Cr, and Mn, wherein the molar percentage of Mo is 5-15%, and the total molar percentage of Fe and Mo is 35%.

[0008] Optionally, the molar ratio of Ni, Fe, Mo, Cr, and Mn in the catalyst is 10:5:2:2:1.

[0009] Optionally, the catalyst surface has a nitrided layer.

[0010] Optionally, the thickness of the nitrided layer is 40 μm to 50 μm.

[0011] Optionally, the surface nitrogen content of the catalyst is 25%, which is gradually reduced to 5% from the outside to the inside in three gradients.

[0012] Optionally, the thickness of the catalyst is 40 μm to 60 μm.

[0013] Optionally, the electrode substrate material includes one of nickel mesh, nickel foam, and carbon paper.

[0014] Secondly, this application provides a method for preparing an alkaline hydrogen production electrode, comprising the following steps:

[0015] S1. Weigh Ni, Fe, Mo, Cr, and Mn powders, melt them in an inert gas atmosphere, and atomize them to obtain catalyst powder, wherein the molar percentage of Mo powder is 5-15%;

[0016] S2. The catalyst powder is loaded onto the electrode substrate and then vacuum annealed.

[0017] Optionally, in step S1, the particle size of the Ni, Fe, Mo, Cr, and Mn powders is 45 μm to 75 μm.

[0018] Optionally, the melting parameters are: vacuum degree ≤ 10. -3 Pa, current 1600A~2200A.

[0019] Optionally, the parameters for the vacuum annealing process are: a processing temperature of 700℃~900℃ and a processing time of 2h~6h.

[0020] Optionally, this application provides a method for preparing an alkaline hydrogen production electrode, further comprising: S3, performing surface plasma nitriding treatment, wherein the surface plasma nitriding treatment step is as follows:

[0021] Place the electrodes in the vacuum chamber and evacuate the vacuum level to 4 × 10⁻⁴. -3 Pa ~ 6×10 -3 Pa, argon gas is introduced to 90Pa~110Pa; negative bias voltage is applied to generate plasma, and the temperature is raised to 350℃~450℃ at a rate of 5~15℃ / min. Hydrogen gas is introduced for activation to remove oxides from the electrode surface; then nitrogen gas is introduced for nitriding.

[0022] Nitriding is divided into three stages:

[0023] First stage: Time 0.1h~1h, temperature 460℃~550℃, nitrogen to hydrogen volume ratio 3.5~4.5:1, pressure 200Pa~400Pa, voltage 650V~850V;

[0024] Second stage: Time 1h~3h, temperature 500℃~650℃, nitrogen to hydrogen volume ratio 2.5~1.5:1, pressure 400Pa~600Pa, voltage 550V~650V;

[0025] The third stage: time 1h~2h, temperature 550℃~680℃, nitrogen to hydrogen volume ratio 0.5~1.5:1, pressure 700Pa~900Pa, voltage 350V~450V;

[0026] A nitrided layer with a surface nitrogen content of 25% is formed on the catalyst surface, which is divided into three gradients from the outside to the inside, gradually decreasing to a nitrogen content of 5%.

[0027] The beneficial effects of this application are:

[0028] The alkaline hydrogen production electrode provided in the first aspect of this application enhances catalytic activity through alloying and the introduction of Mo, as well as controlling the content of Fe and Mo. Compared with existing binary Raney nickel, it has higher catalytic activity, which can effectively reduce the overpotential of the HER reaction, thereby reducing the energy consumption of the electrolyzer. Furthermore, Cr and Mn can enhance the corrosion resistance of the electrode.

[0029] The method for preparing the alkaline hydrogen production electrode provided in the second aspect of this application involves introducing an appropriate amount of Mo (5-15%) and combining it with Fe, Cr, and Mn to form a multi-element alloy catalyst. Mo promotes water dissociation, Fe and Mn optimize the electronic structure, and Cr enhances corrosion resistance, improves intrinsic catalytic activity, and reduces hydrogen evolution overpotential. Vacuum annealing is then used to enhance the metallurgical bond between the powder and the substrate, thereby improving conductivity and interfacial stability. Gradient nitriding is used to construct a multilayer structure with a high nitrogen content (25%) on the surface and decreasing to 5% in the inner layer, forming highly active Ni-N / Mo-N sites and relieving stress. The gradient nitriding layer exhibits both high activity and long lifespan, adapting to fluctuations in green electricity and frequent start-stop conditions. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0031] In a first aspect, this application provides an alkaline hydrogen production electrode, comprising: an electrode substrate and a catalyst supported on the electrode substrate;

[0032] The catalyst comprises the following components: Ni, Fe, Mo, Cr, and Mn, wherein the molar percentage of Mo is 5-15%, and the total molar percentage of Fe and Mo is 35%.

[0033] The alkaline hydrogen production electrode provided in the first aspect of this application enhances catalytic activity through alloying and the introduction of Mo, as well as controlling the content of Fe and Mo. Compared with existing binary Raney nickel, it has higher catalytic activity, which can effectively reduce the overpotential of the HER reaction, thereby reducing the energy consumption of the electrolyzer. Furthermore, Cr and Mn can enhance the corrosion resistance of the electrode.

[0034] In one possible implementation, the molar ratio of Ni, Fe, Mo, Cr, and Mn in the catalyst is 10:5:2:2:1. This technical solution further enhances the catalytic activity of the catalyst and reduces the overpotential of the HER reaction and the energy consumption of the electrolyzer.

[0035] In one possible implementation, the catalyst surface has a nitride layer. By introducing nitrogen into the catalyst surface to form a metal nitride, the electronic structure and surface chemistry of the material are altered. Nitrogen atoms are more electronegative than metal atoms, and after the formation of the metal nitride, they attract electrons from the metal atoms, causing the d-band center of the metal to shift upwards, enhancing the attraction to reaction intermediates (such as...). The adsorption capacity of nitrides (such as Ni3N and Mo2N) significantly enhances the intrinsic catalytic activity of the hydrogen evolution reaction (HER). Nitrides possess metal-like conductivity, effectively reducing the charge transfer resistance at the electrode / electrolyte interface, improving current response speed, and adapting to green electricity fluctuations. The presence of the nitride layer ensures the adsorption capacity of OH groups. - While promoting ion conduction, it also suppresses the damage of impurity ions to the electrode, thus extending the electrode life.

[0036] In one possible implementation, the thickness of the nitride layer is 40 μm to 50 μm. Precisely controlling the nitride layer thickness within the 40–50 μm range is an optimized result considering catalytic activity, stability, and process feasibility. This thickness range provides sufficient catalytic surface area and bulk reaction participation capacity, avoiding the problems of insufficient active sites and easy electrolyte penetration leading to substrate corrosion caused by excessively thin layers (<40 μm). A thickness ≥40 μm can form a continuous and dense nitride layer, effectively blocking OH... - Ions and water molecules diffuse inward, preventing corrosion of the base metal and extending electrode life. However, if the nitride layer is too thick (50 μm), it may lead to: increased internal stress, making it prone to cracking or peeling; longer charge transport paths, increasing resistance; increased fabrication costs and energy consumption; and increased process difficulty. Therefore, 40 μm to 50 μm is considered the "golden range" for balancing performance and reliability.

[0037] In one possible implementation, the nitrogen content of the catalyst surface layer is 25%, gradually decreasing to 5% in three gradients from the outside in. Specifically, this scheme achieves synergistic optimization of catalytic activity and stability by constructing a multilayer structure with a surface nitrogen content of 25% and a gradient decreasing to 5% from the outside in. High nitrogen doping of the surface layer significantly modulates the electronic structure of metals such as Ni and Mo, reduces the d-orbital electron density, and optimizes the hydrogen adsorption free energy (ΔG_ This process forms numerous Ni-N and Mo-N active sites, enhancing the kinetics of the hydrogen evolution reaction. Simultaneously, it promotes the formation of a hydrophilic oxide layer, accelerating water molecule adsorption and dissociation (Volmer step). The gradient nitrogen content effectively alleviates thermal stress and lattice mismatch between the nitride layer and the substrate, suppressing cracks and spalling, and strengthening interfacial adhesion. It also achieves a smooth bandgap transition, lowers the charge transport barrier, improves conductivity, and slows nitrogen diffusion, maintaining long-term structural stability. The inner layer retains 5% nitrogen content, enhancing the metallurgical bond between the nitride layer and the substrate, anchoring the active layer, and maintaining the substrate's conductivity and mechanical strength. This gradient structure combines high activity, strong durability, and resistance to fluctuations, making it suitable for high-efficiency alkaline hydrogen production electrodes under complex operating conditions.

[0038] In one possible implementation, the catalyst thickness is 40 μm to 60 μm. This thickness range ensures sufficient active site density and reaction depth in the catalyst layer, increasing the electrochemical surface area and thus enhancing the catalytic current density of the hydrogen evolution reaction (HER). Simultaneously, this thickness forms a continuous and dense active layer, effectively blocking the erosion of the metal substrate (such as a nickel mesh) by the alkaline electrolyte, inhibiting substrate oxidation and corrosion, and extending electrode life. The 40 μm to 60 μm thickness also balances electron conduction pathways and mass transfer efficiency: too thin (<40 μm) easily leads to incomplete coverage and poor durability; too thick (60 μm) increases internal resistance and mass transfer resistance, potentially causing coating cracking, peeling, or hindered reactant diffusion. Furthermore, this thickness range facilitates the establishment of a stable thermal field and compositional gradient during preparation, supporting the realization of structures such as gradient nitrogen doping, and improving the mechanical and electrochemical stability of the electrode under frequent start-stop cycles and fluctuating currents.

[0039] In one possible implementation, the electrode substrate material includes one of nickel mesh, nickel foam, or carbon paper. Among these materials, nickel mesh and nickel foam possess high conductivity and a three-dimensional porous structure, which is beneficial for catalyst loading, mass transfer, and electron transport. They also have a compositional match with nickel-based catalysts, resulting in interface stability. Carbon paper is corrosion-resistant, lightweight, and has uniform pores, which can reduce weight and increase flexibility. All three materials can effectively support the catalyst layer, ensuring the structural and performance stability of the electrode under long-term operation and frequent start-stop cycles.

[0040] Secondly, this application provides a method for preparing an alkaline hydrogen production electrode, comprising the following steps:

[0041] S1. Weigh Ni, Fe, Mo, Cr, and Mn powders, melt them in an inert gas atmosphere, and atomize them to obtain catalyst powder, wherein the molar percentage of Mo powder is 5-15%;

[0042] S2. The catalyst powder is loaded onto the electrode substrate and then vacuum annealed.

[0043] The method for preparing the alkaline hydrogen production electrode provided in the second aspect of this application involves introducing an appropriate amount of Mo (5-15 mol%) and combining it with Fe, Cr, and Mn to form a multi-element alloy catalyst. Mo promotes water dissociation, Fe and Mn optimize the electronic structure, and Cr enhances corrosion resistance, improves intrinsic catalytic activity, and reduces hydrogen evolution overpotential. Vacuum annealing is then used to enhance the metallurgical bond between the powder and the substrate, thereby improving conductivity and interfacial stability. Gradient nitriding is used to construct a multilayer structure with a high nitrogen content (25%) on the surface and decreasing to 5% in the inner layer, forming highly active Ni-N / Mo-N sites and relieving stress. The gradient nitriding layer exhibits both high activity and long lifespan, adapting to fluctuations in green electricity and frequent start-stop conditions.

[0044] In one possible implementation, the particle size of Ni, Fe, Mo, Cr, and Mn powders in step S1 is 45 μm to 75 μm. Specifically, controlling the particle size of Ni, Fe, Mo, Cr, and Mn powders to 45 μm to 75 μm maintains good flowability and mixing uniformity during melting and atomization, which is beneficial for forming a homogeneous multi-element alloy powder. During loading and vacuum annealing, the appropriate particle size helps to achieve dense packing, promotes metallurgical bonding between particles and with the substrate, and improves interface stability. At the same time, it provides a uniform diffusion channel for subsequent gradient nitriding, which is conducive to forming a gradient nitriding layer with continuous structure and controllable nitrogen content distribution. This particle size range avoids the problems of easy agglomeration and oxidation of excessively fine powders and small specific surface area, rough coating, and poor adhesion of excessively coarse powders. It can obtain a high-density, low-porosity catalyst layer, improve conductivity and mechanical strength, ensure nitriding quality, enhance the catalytic activity and long-term durability of the electrode, and is suitable for large-scale preparation processes such as spraying and pressure coating. The process is stable and conducive to industrial application.

[0045] In one possible implementation, the melting parameters are: vacuum degree ≤ 10. -3 Pa, current 1600A~2200A. Specifically, in a vacuum degree ≤10 -3Melting under a high vacuum environment (Pa) effectively reduces interference from impurity gases such as oxygen, nitrogen, and water vapor, suppressing the oxidation and inclusion of metal powders like Ni, Fe, Mo, Cr, and Mn at high temperatures. This ensures the purity and uniformity of the alloy composition and avoids the formation of inactive oxide phases that affect catalytic performance. Simultaneously, the high vacuum helps remove gases and volatile impurities from the melt, increasing alloy density. Using a high current of 1600A~2200A for arc or induction melting provides sufficient heat energy in a short time, enabling rapid and uniform melting of various metal powders. This promotes full diffusion and alloying between elements, forming structurally uniform and compositionally stable multi-element alloys (such as Ni-Fe-Mo-Cr-Mn). This current range balances melting efficiency and temperature controllability, avoiding incomplete fusion and component segregation due to excessively low current, or localized overheating, element volatilization, and increased energy consumption due to excessively high current. This combination of smelting parameters ensures the high purity, high uniformity, and good metallurgical quality of the alloy powder, laying a material foundation for subsequent atomization powdering, catalyst loading, and gradient nitriding, and is conducive to improving the catalytic activity and stability of the final electrode.

[0046] In one possible implementation, the parameters for vacuum annealing are: a treatment temperature of 700℃ to 900℃ and a treatment time of 2h to 6h. For example, the treatment temperature can be any typical but non-limiting point value or a range between any two points, such as 700℃, 750℃, 800℃, 850℃, or 900℃. The treatment time can be any typical but non-limiting point value or a range between any two points, such as 2h, 3h, 4h, 5h, or 6h. In this case, annealing in a vacuum environment effectively prevents the catalyst powder and substrate from oxidizing at high temperatures, maintaining the cleanliness and compositional stability of the material surface. The temperature range of 700℃ to 900℃ is sufficient to activate atomic diffusion, promoting inter-atomic diffusion between catalyst particles and between the catalyst and the substrate, forming a good metallurgical bond, and significantly enhancing coating adhesion and interfacial conductivity. Simultaneously, this temperature range can eliminate internal stress generated in the powder during melting, atomization, and loading processes, improving lattice integrity, reducing defect density, and enhancing the crystallinity and electronic conductivity of the material. Annealing time is controlled between 2 and 6 hours, ensuring sufficient thermal activation and structural relaxation while avoiding excessive grain growth or elemental segregation caused by prolonged processing. This process helps to construct a stable, low-resistivity, and high-bonding-strength electrode structure, providing a guarantee for subsequent surface plasma nitriding treatment and long-term stable operation of the electrode under high current density and frequent start-stop conditions.

[0047] In one possible implementation, this application provides a method for preparing an alkaline hydrogen production electrode, further comprising: S3, performing surface plasma nitriding treatment, wherein the surface plasma nitriding treatment step is as follows:

[0048] Place the electrodes in the vacuum chamber and evacuate the vacuum level to 4 × 10⁻⁴.-3 Pa ~ 6×10 -3 Pa, argon gas is introduced to 90Pa~110Pa; negative bias voltage is applied to generate plasma, and the temperature is raised to 350℃~450℃ at a rate of 5~15℃ / min. Hydrogen gas is introduced for activation to remove oxides from the electrode surface; then nitrogen gas is introduced for nitriding.

[0049] For example, the vacuum level can be evacuated to 4 × 10⁻⁶. -3 Pa, 5×10 -3 Pa, 6×10 -3 Typical but non-limiting point values ​​or ranges between any two points such as Pa; the introduction of argon gas can reach typical but non-limiting point values ​​or ranges between any two points such as 90 Pa, 100 Pa, 105 Pa, 110 Pa; the temperature can be raised to typical but non-limiting point values ​​or ranges between any two points such as 350℃, 400℃, 450℃.

[0050] Nitriding is divided into three stages:

[0051] First stage: Time 0.1h~1h, temperature 460℃~550℃, nitrogen to hydrogen volume ratio 3.5~4.5:1, pressure 200Pa~400Pa, voltage 650V~850V;

[0052] Second stage: Time 1h~3h, temperature 500℃~650℃, nitrogen to hydrogen volume ratio 2.5~1.5:1, pressure 400Pa~600Pa, voltage 550V~650V;

[0053] The third stage: time 1h~2h, temperature 550℃~680℃, nitrogen to hydrogen volume ratio 0.5~1.5:1, pressure 700Pa~900Pa, voltage 350V~450V;

[0054] A nitrided layer with a surface nitrogen content of 25% is formed on the catalyst surface, which is divided into three gradients from the outside to the inside, gradually decreasing to a nitrogen content of 5%.

[0055] For example, the time for the first stage of nitriding can be any typical but non-limiting point value or a range between any two points, such as 0.1h, 0.5h, 0.8h, or 1h; the temperature can be any typical but non-limiting point value or a range between any two points, such as 460℃, 480℃, 500℃, 520℃, or 550℃; the volume ratio of nitrogen to hydrogen can be any typical but non-limiting point value or a range between any two points, such as 3.5:1, 4:1, or 4.5:1; the pressure can be any typical but non-limiting point value or a range between any two points, such as 200Pa, 250Pa, 300Pa, 350Pa, or 400Pa; and the voltage can be any typical but non-limiting point value or a range between any two points, such as 650V, 700V, 750V, 800V, or 850V. In this case, by combining low temperature with high nitrogen partial pressure and high voltage, a large number of nitrogen ions are rapidly injected into the surface layer under a strong electric field, quickly forming a surface layer with high nitrogen content (25%), and constructing a highly active catalytic region.

[0056] For example, the time for the second-stage nitriding can be any typical but non-limiting point value or a range between any two points, such as 1h, 2h, or 3h; the temperature can be any typical but non-limiting point value or a range between any two points, such as 500℃, 580℃, 600℃, or 650℃; the volume ratio of nitrogen to hydrogen can be any typical but non-limiting point value or a range between any two points, such as 2.5:1, 2:1, or 1.5:1; the pressure can be any typical but non-limiting point value or a range between any two points, such as 400Pa, 450Pa, 500Pa, 550Pa, or 600Pa; and the voltage can be any typical but non-limiting point value or a range between any two points, such as 550V, 600V, 620V, or 650V. In this situation, by increasing the temperature and decreasing the voltage, the nitrogen ion implantation rate is slowed down, and thermal diffusion becomes the main method, allowing surface nitrogen atoms to slowly diffuse inward, forming an intermediate transition zone with nitrogen content decreasing from high to low, thus alleviating stress concentration.

[0057] For example, the time for the third-stage nitriding can be any typical but non-limiting point value or a range between any two points, such as 1 h, 1.5 h, or 2 h; the temperature can be any typical but non-limiting point value or a range between any two points, such as 550 °C, 600 °C, 650 °C, or 680 °C; the volume ratio of nitrogen to hydrogen can be any typical but non-limiting point value or a range between any two points, such as 0.5:1, 1:1, or 1.5:1; the pressure can be any typical but non-limiting point value or a range between any two points, such as 700 Pa, 750 Pa, 800 Pa, 850 Pa, or 900 Pa; and the voltage can be any typical but non-limiting point value or a range between any two points, such as 350 V, 400 V, or 450 V. In this case, further heating enhances the bulk diffusion capacity, allowing nitrogen to penetrate deeply into the substrate. At the same time, low voltage reduces surface nitrogen supersaturation, forming a multilayer structure with a nitrogen content gradient decreasing from the surface to the interior (25%→5%), thus improving bonding strength and structural stability.

[0058] The entire process utilizes temperature gradient, increasing gas pressure, decreasing nitrogen-hydrogen ratio, and decreasing voltage to synergistically control the infiltration and diffusion kinetics of nitrogen, achieving a high-performance gradient nitrided layer with continuous transitions in composition, stress, and energy bands, while balancing high activity and long lifespan.

[0059] To enable those skilled in the art to clearly understand the above-described implementation details and operations of this application, and to demonstrate the significant advancements in the performance of the alkaline hydrogen production electrode and its preparation method in the embodiments of this application, the following examples illustrate the above technical solutions. Example 1

[0060] Preparation of alkaline hydrogen production electrode:

[0061] S1. Weigh out powders containing 50% Ni, 25% Fe, 10% Mo, 10% Cr, and 5% Mn according to molar percentage. In an argon atmosphere with a vacuum degree ≤10... -3 The catalyst powder was obtained by melting at Pa and 2000A current and then atomizing.

[0062] S2. The catalyst powder is plasma-sprayed onto nickel foam and then vacuum annealed at 800℃ for 4 hours.

[0063] S3. Surface plasma nitriding treatment: The electrode is placed in a vacuum chamber, and the vacuum level is evacuated to 5×10⁻⁶. -3 Pa, argon gas is introduced to 100 Pa, negative bias voltage is applied to generate plasma, the temperature is raised to 400℃ at a rate of 10℃ / min, and then hydrogen gas is introduced for activation to remove oxides from the electrode surface.

[0064] Nitriding is divided into three stages:

[0065]

[0066] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, surface nitrogen content 25%, gradually decreasing to 5% in the inner layer; performance: 5000A / m 2 The HER overpotential was 248 mV, and after 1000 CV cycles, the HER overpotential was 258 mV. The ultrasonic weight loss rate was 0.93% at 30% KOH, 60℃, and 600W.

[0067] At a high current density of 5000 A / m², only an overpotential of 248 mV is required to drive the hydrogen evolution reaction (HER), indicating that the electrode material possesses extremely high intrinsic catalytic activity. After 1000 CV cycles, the HER overpotential only increased by 10 mV (from 248 mV to 258 mV), demonstrating that the catalytic active sites of the electrode remain stable during repeated redox cycles and exhibit excellent electrochemical durability.

[0068] Comparative Example 1

[0069] Preparation of alkaline hydrogen production electrode:

[0070] Weigh out powders containing 50% Ni, 30% Fe, 10% Mo, and 10% Cr according to the molar percentage; the remaining methods are the same as in Example 1.

[0071] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, performance: 5000A / m 2 The HER overpotential was 281 mV, and after 1000 CV cycles, the HER overpotential was 324 mV. The ultrasonic weight loss rate was 1.53% at 30% KOH, 60℃, and 600W.

[0072] This indicates that without the addition of Mn, the electrode exhibits a higher ultrasonic weight loss rate and a greater decay rate after cycling in an alkaline environment.

[0073] Comparative Example 2

[0074] Preparation of alkaline hydrogen production electrode:

[0075] Weigh out powders containing 50% Ni, 30% Fe, 5% Mo, 10% Cr, and 5% Mn according to the molar percentage; the remaining methods are the same as in Example 1.

[0076] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, performance: 5000A / m 2 The HER overpotential was 263 mV, and after 1000 CV cycles, the HER overpotential was 281 mV. The ultrasound weight loss rate was 0.95% at 30% KOH, 60℃, and 600W.

[0077] This indicates that when less Mo is added, the synergistic effect between Ni and Mo metals is weak, and the electrode catalytic activity is relatively poor.

[0078] Comparative Example 3

[0079] Preparation of alkaline hydrogen production electrode:

[0080] Weigh out powders containing 50% Ni, 15% Fe, 20% Mo, 10% Cr, and 5% Mn according to the molar percentage; the remaining methods are the same as in Example 1.

[0081] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, performance: 5000A / m 2 The HER overpotential was 243mV, and after 1000 CV cycles, the HER overpotential was 295mV. The ultrasound weight loss rate was 1.03% at 30% KOH, 60℃, and 600W.

[0082] This indicates that the electrode stability is poor when a large amount of Mo is added. Example 2

[0083] Preparation of alkaline hydrogen production electrode:

[0084] Weigh out powders containing 50% Ni, 25% Fe, 10% Mo, 10% Cr, and 5% Mn according to the molar percentage; no surface plasma nitriding treatment is performed, and the remaining methods are the same as in Example 1;

[0085] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, performance: 5000A / m 2 The HER overpotential was 251 mV, and after 1000 CV cycles, the HER overpotential was 282 mV. The ultrasound weight loss rate was 1.25% at 30% KOH, 60℃, and 600W.

[0086] This indicates that without surface plasma nitriding treatment, the electrode stability is affected.

[0087] Comparative Example 4

[0088] Preparation of alkaline hydrogen production electrode:

[0089] The surface plasma nitriding treatment method is different, but the other methods are the same as in Example 1;

[0090] The specific methods for surface plasma nitriding treatment are as follows:

[0091]

[0092] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, surface nitrogen content 15%, performance: 5000A / m 2The HER overpotential was 259 mV, and after 1000 CV cycles, the HER overpotential was 297 mV. The ultrasound weight loss rate was 1.24% at 30% KOH, 60℃, and 600W.

[0093] This indicates that the nitrogen content on the surface of the nitrided layer needs to be controlled at around 20%-30%. If the nitrogen content on the surface is too low, it cannot provide effective protection.

[0094] Comparative Example 5

[0095] Preparation of alkaline hydrogen production electrode:

[0096] The surface plasma nitriding treatment method is different, but the other methods are the same as in Example 1;

[0097] The specific methods for surface plasma nitriding treatment are as follows:

[0098]

[0099] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, surface nitrogen content 40%, performance 5000A / m 2 The HER overpotential was 275mV, and after 1000 CV cycles, the HER overpotential was 302mV. The ultrasonic weight loss rate was 0.89% at 30% KOH, 60℃, and 600W.

[0100] This indicates that the nitrogen content on the surface of the nitrided layer needs to be controlled at around 20%-30%. If the nitrogen content on the surface is too high, it will affect the contact between the electrolyte and the internal active sites.

[0101] Comparative Example 6

[0102] Preparation of alkaline hydrogen production electrode:

[0103] The surface plasma nitriding treatment method is different, but the other methods are the same as in Example 1;

[0104] The specific methods for surface plasma nitriding treatment are as follows:

[0105]

[0106] Nickel foam: 95% porosity, 1mm thickness; resulting electrode thickness 50µm, surface nitrogen content 25%, deep nitrogen content 15%, performance: 5000A / m 2 The HER overpotential was 256 mV, and after 1000 CV cycles, the HER overpotential was 276 mV. The ultrasound weight loss rate was 0.89% at 30% KOH, 60℃, and 600W.

[0107] This indicates that excessively high deep nitrogen content and low porosity will also affect electrolyte contact and reduce activity. The deep nitrogen content should be controlled at around 5%.

[0108] Comparing Example 1 with Comparative Examples 1-3, the introduction of an appropriate amount of Mo (5-15%) and the combination of Fe, Cr, and Mn to form a multi-element alloy catalyst enhanced the synergistic effect between Ni / Mo metals, thereby improving the electrode catalytic activity. Comparing Example 2 with Comparative Examples 4-6, the gradient nitriding scheme improved electrode stability.

[0109] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0110] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. An alkaline hydrogen production electrode, characterized in that, include: Electrode substrate and catalyst supported on the electrode substrate; The catalyst comprises the following components: Ni, Fe, Mo, Cr, and Mn, wherein the molar percentage of Mo is 5-15%, and the total molar percentage of Fe and Mo is 35%. The catalyst surface has a nitrided layer; The catalyst has a surface nitrogen content of 25%, which gradually decreases to 5% from the outside to the inside in three gradients.

2. The alkaline hydrogen production electrode according to claim 1, characterized in that, The molar ratio of Ni, Fe, Mo, Cr, and Mn in the catalyst is 10:5:2:2:

1.

3. The alkaline hydrogen production electrode according to claim 1, characterized in that, The thickness of the nitrided layer is 40μm~50μm.

4. The alkaline hydrogen production electrode according to any one of claims 1-3, characterized in that, The thickness of the catalyst is 40 μm to 60 μm; And / or, the material of the electrode substrate includes one of nickel mesh, nickel foam, and carbon paper.

5. A method for preparing an alkaline hydrogen production electrode as described in claim 1, characterized in that, Includes the following steps: S1. Weigh Ni, Fe, Mo, Cr, and Mn powders, melt them in an inert gas atmosphere, and atomize them to obtain catalyst powder, wherein the molar percentage of Mo powder is 5~15%, and the total molar percentage of Fe and Mo is 35%; S2. Load the catalyst powder onto the electrode substrate and then perform vacuum annealing. S3. Perform surface plasma nitriding treatment, the steps of which are as follows: Place the electrodes in the vacuum chamber and evacuate the vacuum level to 4 × 10⁻⁴. -3 Pa ~ 6×10 -3 Pa, argon gas is introduced to 90Pa~110Pa; A negative bias voltage is applied to generate plasma, and the temperature is raised to 350℃~450℃ at a rate of 5~15℃ / min. Hydrogen gas is introduced for activation to remove oxides from the electrode surface; then nitrogen gas is introduced for nitriding.

6. The method for preparing the alkaline hydrogen production electrode according to claim 5, characterized in that, In step S1, the particle size of Ni, Fe, Mo, Cr, and Mn powders is 45 μm to 75 μm.

7. The method for preparing the alkaline hydrogen production electrode according to claim 5, characterized in that, The parameters for the smelting are: vacuum degree ≤ 10. -3 Pa, current 1600A~2200A; And / or, the parameters for the vacuum annealing process are: a processing temperature of 700℃~900℃ and a processing time of 2h~6h.

8. The method for preparing the alkaline hydrogen production electrode according to any one of claims 5 to 7, characterized in that, Nitriding is divided into three stages: First stage: Time 0.1h~1h, temperature 460℃~550℃, nitrogen to hydrogen volume ratio 3.5~4.5:1, pressure 200Pa~400Pa, voltage 650V~850V; Second stage: Time 1h~3h, temperature 500℃~650℃, nitrogen to hydrogen volume ratio 2.5~1.5:1, pressure 400Pa~600Pa, voltage 550V~650V; The third stage: time 1h~2h, temperature 550℃~680℃, nitrogen to hydrogen volume ratio 0.5~1.5:1, pressure 700Pa~900Pa, voltage 350V~450V; A nitrided layer with a surface nitrogen content of 25% is formed on the catalyst surface, which is divided into three gradients from the outside to the inside, gradually decreasing to a nitrogen content of 5%.

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