Anode coating, anode as well as preparation method and application of anode

Abstract

The invention belongs to the field of water electrolysis hydrogen production, and particularly provides a coating on the surface of an anode in the field of water electrolysis hydrogen production, the anode and a preparation method and application of the anode. The coating on the surface of the anode for hydrogen production through water electrolysis comprises a bottom layer, a middle layer and a surface layer which are arranged in sequence, the bottom layer contains Ni and Cr; the middle layer contains Ni, Mo and Zn; and the surface layer contains RuO2 and IrO2. According to the anode coating disclosed by the invention, through a unique gradient composite design and a multi-layer structure containing specific components, the bottom layer, the middle layer and the surface layer are mutually matched and synergistically achieve the technical effects of strong binding force with a base material, excellent electrochemical performance and remarkable improvement of hydrogen production efficiency. Meanwhile, the invention further provides an anode containing the specific gradient coating structure, a preparation method of the anode and application of the anode in hydrogen production through water electrolysis.

Description

Technical Field

[0001] This invention relates to an anode for hydrogen production by water electrolysis, and more particularly to an anode coating, an anode, and its application for hydrogen production by alkaline water electrolysis. Background Technology

[0002] Driven by the global energy transition and the "dual carbon" goal, alkaline water electrolysis for hydrogen production has become one of the core pathways for large-scale "green hydrogen" production due to its mature technology and controllable cost. The anode of the alkaline electrolyzer, as the core carrier of the oxygen evolution reaction (OER), directly determines the energy consumption level and lifespan of the electrolysis system. However, inherent defects in current anode materials and preparation processes severely restrict the industrialization process of alkaline water electrolysis for hydrogen production.

[0003] Traditional alkaline electrolytic cells commonly use nickel-based materials (such as pure nickel or nickel alloys) as anodes. However, these materials face a dual challenge in strongly alkaline electrolytes (typically 30%-35% KOH solution) and high-potential oxygen evolution environments: On the one hand, the intrinsic catalytic activity of nickel-based materials is insufficient, with oxygen evolution reaction overpotentials reaching 300-500mV, resulting in high energy consumption in the electrolytic cell (theoretical decomposition voltage 1.23V, actual operating voltage generally >1.8V); on the other hand, the synergistic effect of electrolyte corrosion and bubble erosion easily causes the anode coating to peel off. Under typical operating conditions, the electrode life is only 500-1000 hours, and frequent electrode replacement not only increases maintenance costs but also leads to system downtime losses. Existing technologies (such as patent CN202410851441.6) use nickel-molybdenum alloy anodes prepared by electrodeposition, which improve catalytic activity, but the coating and substrate only form a mechanical bond with a bonding strength of less than 20MPa, making them prone to lamellar peeling under bubble erosion.

[0004] Plasma spraying, with its advantages of high deposition efficiency and adjustable coating composition, is considered a potential solution for improving anode performance. However, traditional plasma spraying technology has revealed two major problems in application: First, during the spraying process, high-temperature particles easily form oxide inclusions upon contact with air, resulting in a coating porosity as high as 10%-15%, which accelerates coating detachment after electrolyte penetrates along the pores to the interface. Second, the spraying thermal stress is mismatched with the thermal expansion coefficients of the substrate and coating (e.g., the difference in thermal expansion coefficients between nickel-based coatings and titanium substrates can reach 40%), leading to microcracks at the interface and a high ultrasonic weight loss rate. For example, in patent CN202310204878.6, a RuO2 / Ni anode prepared using ordinary plasma spraying showed a coating detachment area exceeding 30% and a current density decrease of 25% after 500 hours of electrolysis in a 6M KOH solution.

[0005] Furthermore, the contradiction between the demands of industrial production and existing processes is becoming increasingly prominent. Traditional manual spraying or batch processing methods are difficult to meet the requirements of large-scale production, while automated spraying equipment still needs optimization in terms of parameter consistency control and coating uniformity. This results in high costs (cost per square meter of electrode > 2000 yuan) and low yields (< 75%) for existing anode preparation processes, becoming a key factor restricting the large-scale application of alkaline water electrolyzers.

[0006] Therefore, how to achieve a synergistic improvement in anodic bonding force and catalytic activity while reducing production costs through coating structure innovation, process parameter optimization, and equipment linkage design is a technical challenge that urgently needs to be overcome in the field of alkaline water electrolysis hydrogen production. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an anode coating based on plasma spraying technology, formed through a gradient composite coating design, exhibiting strong adhesion to the substrate, significantly improved and stable electrochemical performance. Furthermore, this invention also provides an anode with this coating, its preparation method, and its application in water electrolysis for hydrogen production.

[0008] To achieve the above objectives, in a first aspect, the present invention provides an anodic coating with strong adhesion to the substrate and excellent electrochemical performance. To achieve this objective, the technical solution adopted by the present invention is: an anodic coating, wherein the coating comprises a bottom layer, an intermediate layer and a top layer disposed sequentially;

[0009] The bottom layer contains Ni and Cr;

[0010] The intermediate layer contains Ni, Mo, and Zn;

[0011] The surface layer contains RuO2 and IrO2.

[0012] The anolyte coating of this invention is formed through a gradient composite design, comprising a bottom layer, an intermediate layer, and a top layer arranged sequentially. The bottom layer contains nickel and chromium and is plasma-sprayed onto the substrate, forming a dense transition layer between the substrate and the functional layer. This reduces the difference in thermal expansion between the substrate and the functional layer and provides stable foundation support. The intermediate layer contains nickel, molybdenum, and zinc, which enhances the hydrogen evolution catalytic activity, lowers the reaction activation energy, and improves hydrogen production efficiency. The top layer contains noble metal-doped oxides RuO2 and IrO2, which reduce the oxygen evolution overpotential and optimize the anolyte electrochemical performance. The three layers of the coating are designed in a specific order, and each layer contains specific components. The three layers work together synergistically to achieve strong adhesion to the substrate, excellent electrochemical performance, and significantly improved hydrogen production efficiency.

[0013] The bottom layer is preferably made of nickel-chromium alloy, and the mass content of nickel and chromium contained in the bottom layer is preferably, but not limited to, 80% by mass of Ni and 20% by mass of Cr.

[0014] The intermediate layer is preferably made of a nickel-molybdenum-zinc alloy, and the mass percentages of nickel, molybdenum, and zinc in the intermediate layer are respectively: Ni 60-80%, Mo 15-30%, and Zn 5-15%. More preferably, the mass percentage of Zn in the intermediate layer is 10%.

[0015] Preferably, the mass percentage content of nickel, molybdenum, and zinc in the intermediate layer includes, but is not limited to: 70% Ni, 20% Mo, and 10% Zn; or 65% Ni, 25% Mo, and 10% Zn; or 75% Ni, 15% Mo, and 10% Zn; or 60% Ni and 30% Mo. The Zn mass percentage content is 10%; or the Ni mass percentage content is 68%, the Mo mass percentage content is 22%, and the Zn mass percentage content is 10%; or the Ni mass percentage content is 72%, the Mo mass percentage content is 18%, and the Zn mass percentage content is 10%; or the Ni mass percentage content is 66%, the Mo mass percentage content is 24%, and the Zn mass percentage content is 10%; or the Ni mass percentage content is 69%, the Mo mass percentage content is 21%, and the Zn mass percentage content is 10%.

[0016] In the surface layer, the preferred, but not limited, mass ratio of RuO2 to IrO2 is (1-3):(1-3). The mass ratio of RuO2 to IrO2 includes, for example, any point value or a range of two points such as 1:1, 1:2, 1:3, 2:1, 2:3, 3:1, 3:2, etc.

[0017] In a second aspect, the present invention provides an anode comprising a substrate and a coating applied to the surface of the substrate, the coating being an anode coating as described above.

[0018] The anode provided by this invention comprises a substrate and a coating applied to the surface of the substrate as described above. The coating is applied to the substrate using a plasma spraying process and is a three-layer structure with a specific order and composition designed through a gradient composite process. This results in strong adhesion between the coating and the substrate, effectively solving the problem of coating detachment due to electrolyte corrosion and bubble erosion in existing technologies. This significantly improves the electrode's lifespan and reduces equipment maintenance costs and downtime. Furthermore, the specific composition design of the intermediate and surface layers significantly enhances hydrogen evolution catalytic activity, reduces the reaction activation energy, and effectively lowers the oxygen evolution overpotential, solving the problem of high oxygen evolution reaction overpotential in traditional alkaline electrolyzers.

[0019] Thirdly, the present invention provides an anode preparation method, the method comprising the following steps:

[0020] (1) Pre-treat and preheat the substrate at a temperature of 200-300℃;

[0021] (2) A base layer, an intermediate layer and a top layer are sequentially sprayed on the surface of the substrate using a plasma spraying process. The base layer is coated with Ni-Cr alloy powder, the intermediate layer is coated with Ni-Mo-Zn alloy, and the top layer is coated with RuO2 and IrO2.

[0022] (3) The substrate after spraying is subjected to heat treatment and electrochemical activation treatment to obtain the anode;

[0023] In step (2), the conditions for plasma spraying of the base layer, intermediate layer and surface layer are independent: spraying power of 30-50 kW, powder feeding rate of 20-50 g / min and carrier gas flow rate of 30-50 L / min.

[0024] The anode preparation method of this invention first pre-treats and preheats the substrate. The pre-treatment enhances the surface roughness and activity of the substrate, thereby improving the mechanical and chemical bonding between the coating and the substrate. Simultaneously, the preheating of the substrate, combined with the adjustment and control of the spraying power, powder feed rate, and carrier gas flow rate of the plasma spraying process for the underlayer, intermediate layer, and top layer, significantly reduces thermal stress and improves the density and uniformity of the coating. Finally, the sprayed substrate undergoes heat treatment and electrochemical activation treatment. The heat treatment eliminates internal stress in the coating, increases crystallinity, and improves physical properties and stability. The electrochemical activation treatment forms a porous structure, removes impurities, increases the number of active sites, and enhances catalytic performance.

[0025] In step (1), the temperature for preheating the substrate is 200-300℃, including but not limited to any selection of 200℃, 220℃, 230℃, 250℃, 260℃, 280℃, 290℃, 300℃, or any two of these ranges.

[0026] Preferably, the pretreatment of the substrate in step (1) includes: sandblasting, ultrasonic cleaning, and acid pickling. More preferably, the pretreatment of the substrate in step (1) is: sandblasting the substrate with Al2O3 particles, ultrasonic cleaning with acetone, and acid pickling with HCl. The pretreatment of the substrate, which involves first sandblasting the substrate with Al2O3 particles, then ultrasonic cleaning with acetone, and finally acid pickling with HCl, can significantly enhance the surface roughness and activity of the substrate, and effectively improve the mechanical bonding and chemical adhesion between the coating and the substrate.

[0027] In the pretreatment of the substrate, the particle size of the Al2O3 particles is preferably, but not limited to, 50 μm; the concentration of the HCl is preferably, but not limited to, 3 M.

[0028] In step (2), the plasma spraying process coats the underlayer, intermediate layer, and top layer. The conditions for each of the three layers are selected independently. The spraying power, powder feeding rate, and carrier gas flow rate are each independently selected from 30-50 kW, 20-50 g / min, and 30-50 L / min, respectively. The spraying power for each layer is independent, for example, including but not limited to any selection or any two of the following: 30 kW, 32 kW, 35 kW, 38 kW, 40 kW, 42 kW, 45 kW, 48 kW, and 50 kW. The powder feeding rate for each layer is independent, for example, including but not limited to any selection or any two of the following: 20 g / min, 25 g / min, 30 g / min, 35 g / min, 40 g / min, 45 g / min, and 50 g / min. The carrier gas flow rates for the bottom, intermediate, and top layers are each independent, for example, including but not limited to any selection from 30 L / min, 32 L / min, 35 L / min, 38 L / min, 40 L / min, 42 L / min, 45 L / min, 48 L / min, 50 L / min, etc., or any range formed by any two points. The adjustment and control of the spraying conditions have a significant impact on reducing thermal stress and improving coating density and uniformity. The spraying power, powder feed rate, and carrier gas flow rate for the three-layer spraying need to be strictly controlled within the specified range to effectively reduce thermal stress and improve coating density and uniformity.

[0029] In step (2), the conditions for the plasma spraying process to spray the base layer and the intermediate layer can be the same or different. Preferably, the conditions for the plasma spraying process to spray the base layer and the intermediate layer are the same, that is, when the plasma spraying process is used to spray the base layer and the intermediate layer, the spraying power, powder feeding rate and carrier gas flow rate are exactly the same.

[0030] In step (2), the conditions for the plasma spraying process of the surface layer and the bottom layer can be the same or different. For example, the spraying power of the plasma spraying process of the surface layer is different from that of the bottom layer. Preferably, the spraying power of the surface layer is greater than or equal to that of the bottom layer.

[0031] In step (2), when the plasma spraying process is used to spray the base layer, the spraying conditions include, but are not limited to: a spraying power of 35kW, a powder feeding rate of 30g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 48kW, a powder feeding rate of 45g / min, and a carrier gas flow rate of 50L / min; or a spraying power of 30kW, a powder feeding rate of 20g / min, and a carrier gas flow rate of 30L / min; or a spraying power of 40kW, a powder feeding rate of 35g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 38kW, a powder feeding rate of 32g / min, and a carrier gas flow rate of 45L / min; or The spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 32kW, the powder feeding rate is 28g / min, and the carrier gas flow rate is 38L / min; or the spraying power is 40kW, the powder feeding rate is 35g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 45kW, the powder feeding rate is 48g / min, and the carrier gas flow rate is 50L / min; or the spraying power is 33kW, the powder feeding rate is 25g / min, and the carrier gas flow rate is 30L / min.

[0032] In step (2), when the intermediate layer is sprayed using plasma spraying, the spraying conditions include, but are not limited to: a spraying power of 35kW, a powder feeding rate of 30g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 48kW, a powder feeding rate of 45g / min, and a carrier gas flow rate of 50L / min; or a spraying power of 30kW, a powder feeding rate of 20g / min, and a carrier gas flow rate of 30L / min; or a spraying power of 40kW, a powder feeding rate of 35g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 38kW, a powder feeding rate of 32g / min, and a carrier gas flow rate of 45L / min; or The spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 32kW, the powder feeding rate is 28g / min, and the carrier gas flow rate is 38L / min; or the spraying power is 40kW, the powder feeding rate is 35g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 45kW, the powder feeding rate is 48g / min, and the carrier gas flow rate is 50L / min; or the spraying power is 33kW, the powder feeding rate is 25g / min, and the carrier gas flow rate is 30L / min.

[0033] In step (2), when the plasma spraying process is used to spray the surface layer, the spraying conditions include, but are not limited to: a spraying power of 40kW, a powder feeding rate of 30g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 50kW, a powder feeding rate of 40g / min, and a carrier gas flow rate of 50L / min; or a spraying power of 32kW, a powder feeding rate of 25g / min, and a carrier gas flow rate of 35L / min; or a spraying power of 42kW, a powder feeding rate of 30g / min, and a carrier gas flow rate of 40L / min; or a spraying power of 45kW, a powder feeding rate of 38g / min, and a carrier gas flow rate of 45L / min; or The spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 36kW, the powder feeding rate is 30g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 32kW, the powder feeding rate is 28g / min, and the carrier gas flow rate is 38L / min; or the spraying power is 40kW, the powder feeding rate is 35g / min, and the carrier gas flow rate is 40L / min; or the spraying power is 45kW, the powder feeding rate is 42g / min, and the carrier gas flow rate is 50L / min; or the spraying power is 33kW, the powder feeding rate is 25g / min, and the carrier gas flow rate is 32L / min.

[0034] Preferably, the heat treatment in step (3) is annealing at 400°C for 30-40 minutes in an inert atmosphere, wherein the inert atmosphere is preferably, but not limited to, Ar. The annealing time in the heat treatment includes, for example, any value of 30 minutes, 32 minutes, 35 minutes, 38 minutes, or 40 minutes, or a range formed by any two of these values. The inventors of this application have discovered that when the heat treatment is annealing at 400°C for 30-40 minutes in an inert atmosphere, the heat treatment can eliminate internal stress in the coating, improve crystallinity, and enhance physical properties and stability.

[0035] Preferably, the electrochemical activation treatment in step (3) involves applying 2 A / dm³ to a 6 M KOH solution. 2 The current density treatment lasted for 0.5-1.5 hours. When the electrochemical activation treatment involved applying 2 A / dm³ of KOH solution at a concentration of 6 M... 2 Treatment with current density for 0.5-1.5 hours can form a porous structure, remove impurities, increase the number of active sites, and improve catalytic performance. The electrochemical activation treatment time includes, but is not limited to, any point value or any range formed by any two points, such as 0.5h, 0.6h, 0.8h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, and 1.5h.

[0036] Finally, this invention provides the application of the anode described above in hydrogen production through water electrolysis.

[0037] The anode of this invention comprises three layers of coating formed in a specific order and composition. Through a unique gradient composite coating design, the bottom layer uses a nickel-chromium alloy to form a dense transition layer. Combined with optimized plasma spraying process parameters, substrate pretreatment, and post-treatment processes, the adhesion between the coating and the substrate is significantly enhanced. According to the national standard GB / T45092-2014, the adhesion between the coating and the substrate, measured by ultrasonic weight reduction, reaches 0.32%, a significant improvement over traditional spraying processes. This effectively solves the problem of coating detachment due to electrolyte corrosion and bubble erosion, greatly extending the electrode's lifespan and reducing equipment maintenance costs and downtime. Furthermore, the intermediate nickel-molybdenum-zinc alloy layer significantly enhances hydrogen evolution catalytic activity and reduces the reaction activation energy; the addition of noble metal doped oxides to the surface layer effectively reduces the oxygen evolution overpotential. At 1.8V, the oxygen evolution current density reaches 500mA / cm². 2 The overpotential is reduced by 120mV, significantly improving the efficiency of hydrogen production through alkaline water electrolysis and effectively solving the problem of high overpotential in the oxygen evolution reaction at the anode of traditional alkaline electrolyzers. Therefore, the anode described above can significantly improve hydrogen production efficiency in water electrolysis and has good stability and service life.

[0038] The anolyte coating, anode, preparation method, and application described in this invention have the following excellent effects:

[0039] (1) The coating has a unique gradient composite design, containing a bottom layer, an intermediate layer and a top layer with specific components. The bottom layer has a strong mechanical bond and chemical bond with the substrate, which solves the problem of easy coating peeling in traditional spraying process. The bottom layer, as a transition layer, reduces the thermal expansion difference between the substrate and the functional layer and provides stable basic support. The intermediate layer can significantly improve the hydrogen evolution catalytic activity, reduce the reaction activation energy and improve the hydrogen production efficiency. The addition of noble metal doped oxides to the top layer can effectively reduce the oxygen evolution overpotential, optimize the anodic electrochemical performance, significantly improve the efficiency of alkaline water electrolysis for hydrogen production, and effectively solve the problem of high oxygen evolution reaction overpotential in traditional alkaline electrolyzers.

[0040] (2) The anode comprises a substrate and a coating on the surface of the substrate. The substrate and the coating have a strong bonding force. The synergistic effect of the multi-element alloy intermediate layer and the noble metal doped oxide surface layer in the coating reduces the oxygen evolution reaction (OER) overpotential and improves the catalytic activity of the anode. At a voltage of 1.8V, the oxygen evolution current density can reach 500mA / cm², and the overpotential is reduced by more than 120mV, improving the efficiency of alkaline water electrolysis for hydrogen production. The gradient structure of the coating in the anode alleviates the difference in thermal expansion, and the dense coating reduces electrolyte corrosion. Combined with the post-treatment in the preparation process to eliminate internal stress, the anode has excellent corrosion resistance and anti-bubble erosion ability in strongly alkaline electrolytes. The lifespan is significantly extended under continuous electrolysis conditions, reducing equipment maintenance costs. At the same time, it solves the problems of insufficient bonding force, low catalytic activity, and short lifespan of the anode in the existing alkaline water electrolysis hydrogen production system.

[0041] (3) The anode preparation method, through the gradient structure design of the coating, combines process parameter optimization and post-treatment processes in the plasma spraying process, synergistically resolving the contradiction between bonding force and catalytic activity, achieving a comprehensive improvement in anode performance, and changing the situation of traditional processes where one aspect is neglected. The optimized control of process parameters in the plasma spraying process can form a dense and uniform coating, and significantly improve the mechanical bonding and chemical adhesion between the coating and the substrate. In the post-treatment process, heat treatment under an inert atmosphere can eliminate internal stress in the coating and improve crystallinity, effectively improving the physical properties and stability of the coating, enabling the anode to operate stably for a long time in a complex electrolysis environment. Electrochemical activation treatment can form a porous structure and remove impurities, greatly increasing the number of active sites, further improving the catalytic performance of the anode, and providing more efficient catalytic conditions for alkaline water electrolysis hydrogen production reaction. Meanwhile, the anode preparation method is compatible with automated spraying equipment, such as robotic arm wide-width spraying platforms. Optimized process parameters are compatible with standardized production processes, enabling large-scale, standardized production. This helps reduce production costs, improve production efficiency, and solves the problems of complex processes and high costs in traditional methods. It has good prospects for industrial application and can promote the large-scale application of alkaline water electrolysis hydrogen production technology.

[0042] (4) The application of the anode in water electrolysis for hydrogen production provides a high-performance anode selection for water electrolysis for hydrogen production, which is especially beneficial for the large-scale promotion and application of alkaline water electrolysis for hydrogen production. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of one structure of the anode of the present invention. Detailed Implementation

[0044] The technical solution and achieved technical effects of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all common substances in the art, which can be prepared by conventional methods in the art or purchased directly from the market.

[0045] This invention first provides an anodic coating, which includes a base layer, an intermediate layer, and a surface layer disposed sequentially, as detailed in the attached figure. Figure 1 A three-layer structure above a substrate; the bottom layer contains Ni and Cr, the middle layer contains Ni, Mo and Zn, and the top layer contains RuO2 and IrO2.

[0046] Specifically, the bottom layer has a Ni mass percentage of 80% and a Cr mass percentage of 20%; the middle layer has a Ni mass percentage of 60-80%, a Mo mass percentage of 15-30%, and a Zn mass percentage of 5-15%; and the top layer has a RuO2 to IrO2 mass ratio of (1-3):(1-3).

[0047] The anode coating is constructed using a gradient composite design. The bottom layer, intermediate layer, and top layer are sequentially sprayed onto the substrate using a plasma spraying process. The bottom layer contains nickel and chromium, forming a dense transition layer between the substrate and the functional layer. This reduces the difference in thermal expansion between the substrate and the functional layer and provides stable foundation support. The intermediate layer contains nickel, molybdenum, and zinc, which enhances the hydrogen evolution catalytic activity, lowers the reaction activation energy, and improves hydrogen production efficiency. The top layer contains noble metal-doped oxides RuO2 and IrO2, which reduce the oxygen evolution overpotential and optimize the anode electrochemical performance. The three layers work synergistically to achieve strong adhesion to the substrate, excellent electrochemical performance, and significantly improved hydrogen production efficiency.

[0048] Secondly, the present invention provides an anode, the structural schematic diagram of which is attached. Figure 1 As shown. The anode includes a substrate and a coating applied to the surface of the substrate. The coating includes a base layer, an intermediate layer, and a top layer sequentially applied to the surface of the substrate. The components of the base layer, the intermediate layer, and the top layer are as described above.

[0049] Furthermore, the present invention provides a method for preparing the anode as described above, the method comprising the following steps:

[0050] (1) Pre-treat and preheat the substrate at a temperature of 200-300℃;

[0051] (2) A base layer, an intermediate layer and a top layer are sequentially sprayed onto the surface of the substrate using a plasma spraying process. The base layer is coated with Ni-Cr alloy powder, the intermediate layer with Ni-Mo-Zn alloy, and the top layer with RuO2 and IrO2. The conditions for the plasma spraying process for the base layer, intermediate layer and top layer are independent: spraying power of 30-50 kW, powder feeding rate of 20-50 g / min, and carrier gas flow rate of 30-50 L / min.

[0052] (3) The substrate after spraying is subjected to heat treatment and electrochemical activation treatment to obtain the anode.

[0053] The anode preparation method first pre-treats and preheats the substrate. The pre-treatment enhances the surface roughness and activity of the substrate, thereby improving the mechanical and chemical bonding between the coating and the substrate. Simultaneously, the preheating of the substrate, combined with the adjustment and control of the spraying power, powder feed rate, and carrier gas flow rate for the plasma spraying process (underlayer, intermediate layer, and top layer), significantly reduces thermal stress and improves the density and uniformity of the coating. Finally, the sprayed substrate undergoes heat treatment and electrochemical activation. The heat treatment eliminates internal stress in the coating, increases crystallinity, and improves physical properties and stability. The electrochemical activation treatment forms a porous structure, removes impurities, increases the number of active sites, and enhances catalytic performance.

[0054] Example 1

[0055] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0056] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 250℃.

[0057] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 70%, Mo mass percentage is 20% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0058] The conditions for the base coat spraying are: spraying power of 35kW, powder feeding rate of 30g / min, and carrier gas flow rate of 40L / min.

[0059] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0060] The conditions for surface coating are: coating power of 40kW, powder feeding rate and carrier gas flow rate are the same as those for the base layer.

[0061] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0062] Example 2

[0063] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0064] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 300℃.

[0065] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 65%, Mo mass percentage is 25% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 3:2).

[0066] The conditions for the base coat spraying are: spraying power of 48kW, powder feeding rate of 45g / min, and carrier gas flow rate of 50L / min.

[0067] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0068] The conditions for surface coating are: coating power of 50kW, powder feeding rate of 45g / min, and carrier gas flow rate of the same as that of the base layer.

[0069] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0070] Example 3

[0071] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0072] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 200℃.

[0073] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the substrate surface. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 75%, Mo mass percentage is 15% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 2:3).

[0074] The conditions for the base coat spraying are: spraying power of 30kW, powder feeding rate of 20g / min, and carrier gas flow rate of 30L / min;

[0075] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0076] The conditions for surface coating are: coating power of 32kW, powder feeding rate of 25g / min, and carrier gas flow rate of 35L / min.

[0077] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0078] Example 4

[0079] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0080] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 250℃.

[0081] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 60%, Mo mass percentage is 30% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0082] The conditions for the base coat spraying are: spraying power of 40kW, powder feeding rate of 35g / min, and carrier gas flow rate of 40L / min.

[0083] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0084] The conditions for surface coating are: coating power of 42kW, powder feeding rate of 30g / min, and carrier gas flow rate of the same as that of the base layer.

[0085] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0086] Example 5

[0087] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0088] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 280℃.

[0089] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 70%, Mo mass percentage is 20% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:2).

[0090] The conditions for the base coat spraying are: spraying power of 38kW, powder feeding rate of 32g / min, and carrier gas flow rate of 45L / min.

[0091] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0092] The conditions for surface coating are: coating power of 45kW, powder feeding rate of 38g / min, and carrier gas flow rate of the same as that of the base layer.

[0093] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0094] Example 6

[0095] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0096] (1) Select low carbon steel as the substrate and perform pretreatment. The pretreatment is as follows: first, use Al2O3 particles with a particle size of 50μm for sandblasting, and then use HCl with a concentration of 3M for etching; preheat the pretreated substrate to 260℃.

[0097] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 68%, Mo mass percentage is 22% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0098] The conditions for the base coat spraying are: spraying power of 36kW, powder feeding rate of 30g / min, and carrier gas flow rate of 40L / min.

[0099] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0100] The conditions for surface coating are the same as those for the base coat;

[0101] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0102] Example 7

[0103] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0104] (1) Select titanium alloy as the substrate and perform pretreatment first. The pretreatment is as follows: first, use Al2O3 particles with a particle size of 50μm for sandblasting, then use HCl with a concentration of 3M for etching; then preheat the pretreated substrate to 220℃.

[0105] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the substrate surface. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 72%, Mo mass percentage is 18% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0106] The conditions for the base coat spraying are: spraying power of 32kW, powder feeding rate of 28g / min, and carrier gas flow rate of 38L / min.

[0107] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0108] The conditions for surface coating are the same as those for the base coat;

[0109] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0110] Example 8

[0111] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0112] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 250℃.

[0113] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 70%, Mo mass percentage is 20% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0114] The conditions for the base coat spraying are: spraying power of 40kW, powder feeding rate of 35g / min, and carrier gas flow rate of 40L / min.

[0115] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0116] The conditions for surface coating are the same as those for the base coat;

[0117] (3) The substrate after spraying is first annealed at 400°C for 40 minutes under Ar atmosphere for heat treatment, and then electrochemically activated in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1.5 hours to obtain the anode of this embodiment.

[0118] Example 9

[0119] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0120] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 290℃.

[0121] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 66%, Mo mass percentage is 24% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0122] The conditions for the base coat spraying are: spraying power of 45kW, powder feeding rate of 48g / min, and carrier gas flow rate of 50L / min.

[0123] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0124] The conditions for surface coating are: powder feeding rate of 42 g / min, and the same spraying power and carrier gas flow rate as the base layer.

[0125] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0126] Example 10

[0127] One embodiment of the anode of the present invention is described, wherein the anode is prepared by the following method:

[0128] (1) Select 46 mesh nickel mesh as substrate and perform pretreatment first. The pretreatment is as follows: first, perform sandblasting (Al2O3 particles with a particle size of 50μm), then perform ultrasonic cleaning with acetone, and finally pickle with HCl with a concentration of 3M; then preheat the pretreated substrate to 230℃.

[0129] (2) A plasma spraying process is used to sequentially spray a base layer, an intermediate layer and a top layer on the surface of the substrate. The base layer is coated with Ni-Cr alloy powder (Ni mass percentage is 80% and Cr mass percentage is 20%), the intermediate layer is coated with Ni-Mo-Zn alloy (Ni mass percentage is 69%, Mo mass percentage is 21% and Zn mass percentage is 10%), and the top layer is coated with RuO2 and IrO2 (RuO2 and IrO2 mass ratio is 1:1).

[0130] The conditions for the base coat spraying are: spraying power of 33kW, powder feeding rate of 25g / min, and carrier gas flow rate of 30L / min.

[0131] The conditions for spraying the intermediate layer are the same as those for the base layer;

[0132] The conditions for surface coating are: carrier gas flow rate of 32L / min, and the same coating power and powder feeding rate as the base layer.

[0133] (3) The substrate after spraying is first annealed at 400°C for 30 minutes under Ar atmosphere for heat treatment, and then electrochemically activated by treating it in KOH solution with a concentration of 6M at a current density of 2A / dm² for 1 hour to obtain the anode of this embodiment.

[0134] Comparative Example 1

[0135] This comparative example is an anode. The only difference between this comparative example and Example 1 is that it does not contain the bottom layer of Example 1. In the preparation process, the intermediate layer and the top layer of this comparative example are directly sprayed onto the pretreated and preheated substrate using a plasma spraying process. The spraying materials and conditions are the same as those in Example 1.

[0136] Comparative Example 2

[0137] This comparative example provides an anode, which differs from Example 1 only in that it does not contain the intermediate layer found in Example 1. In the preparation process, the anode of this comparative example is prepared by plasma spraying a base layer followed by direct surface spraying, with the same spraying materials and conditions as Example 1.

[0138] Comparative Example 3

[0139] This comparative example is an anode. The only difference between this comparative example and Example 1 is that it does not contain the surface layer of Example 1. In the preparation process, the anode of this comparative example is prepared by plasma spraying to coat the bottom layer and the intermediate layer before proceeding to step (3). The surface layer is not sprayed. The raw materials and conditions for spraying the bottom layer and the intermediate layer are the same as those in Example 1.

[0140] Comparative Example 4

[0141] This comparative example is an anode. Compared with Example 1, the anode of this comparative example is different in that the bottom layer, intermediate layer and surface layer materials are not sprayed sequentially, but the bottom layer, intermediate layer and surface layer materials are mixed and sprayed at one time to form a single layer coating. The material ratio and total amount of spraying are the same as in Example 1, and the spraying process parameters are the same as the bottom layer spraying conditions in Example 1.

[0142] Comparative Example 5

[0143] This comparative example is an anode, which differs from Example 1 only in the raw material of the bottom layer. In the comparative example anode, an equal amount of pure nickel powder is used to replace the Ni-Cr alloy powder in Example 1, while the other raw materials and spraying process conditions are the same as in Example 1.

[0144] Comparative Example 6

[0145] This comparative example is an anode. The only difference between this comparative example and Example 1 is that the spraying power of the bottom layer, the middle layer and the top layer are different. In the preparation process of this comparative example anode, the spraying power of the bottom layer, the middle layer and the top layer are all 25 kW. The other spraying conditions, raw material ratios, etc. are the same as those in Example 1.

[0146] Comparative Example 7

[0147] This comparative example is an anode. The only difference between this comparative example and Example 1 is that the spraying power of the bottom layer, the middle layer and the top layer are different. In the preparation process of this comparative example anode, the spraying power of the bottom layer, the middle layer and the top layer are all 55kW. The other spraying conditions, raw material ratios, etc. are the same as those in Example 1.

[0148] Comparative Example 8

[0149] This comparative example is an anode. The only difference between this comparative example and Example 1 is that the powder feeding rates of the bottom layer, the middle layer and the surface layer are different. In the preparation process of this comparative example anode, the powder feeding rates of the bottom layer, the middle layer and the surface layer are all 15 g / min. The other spraying conditions, raw material ratios and so on are the same as those in Example 1.

[0150] Comparative Example 9

[0151] This comparative example is an anode. The only difference between this comparative example and Example 1 is that the powder feeding rates of the bottom layer, the middle layer and the surface layer are different. In the preparation process of this comparative example anode, the powder feeding rates of the bottom layer, the middle layer and the surface layer are all 55 g / min. The other spraying conditions, raw material ratios and so on are the same as those in Example 1.

[0152] Example 1

[0153] Effect test of the anode described in this invention

[0154] The anodes described in Examples 1-10 and Comparative Examples 1-9 were used as test objects. The hydrogen evolution overpotential, oxygen evolution overpotential, stability and ultrasonic weight loss rate of each group of anodes were tested according to the method in GB / T 45092-2024 "Electrolysis of water for hydrogen production". The test results of each group are shown in Table 1 below.

[0155] Table 1. Test results of anode performance for each group

[0156]

[0157] As can be seen from the results in Table 1 above:

[0158] The anode of Example 1 exhibited a hydrogen evolution overpotential of 80mV and an oxygen evolution overpotential of 223mV in the water electrolysis hydrogen production experiment. After 500 hours of continuous operation, the performance degradation rate was only 3%, and the ultrasonic weight loss rate was 0.32%, demonstrating balanced physical and electrochemical performance.

[0159] The anode of Example 2 has an ultrasonic weight reduction rate of 0.29%. Due to the excellent density of the coating, there is no leakage under high-pressure electrolysis environment. The hydrogen evolution overpotential is 100mV and the oxygen evolution overpotential is 260mV, making it suitable for long-term operation in high-pressure sealing scenarios.

[0160] The anode of Example 3 has a hydrogen evolution overpotential of 120mV, an oxygen evolution overpotential of 280mV, a decay rate of 5% after 300 hours of continuous operation, and an ultrasonic weight reduction rate of 0.86%, which can meet the application scenarios with low cost and medium performance requirements.

[0161] In Example 4, the high Mo content in the intermediate layer of the anode significantly enhances the hydrogen evolution catalytic activity, reduces the hydrogen evolution overpotential to 56 mV, and has a 500-hour operating decay rate of 4.3%, demonstrating outstanding performance in the field of hydrogen energy production.

[0162] The anode of Example 5 has a high IrO2 content on the surface, which effectively optimizes oxygen evolution performance. The oxygen evolution overpotential is as low as 220mV, and the hydrogen evolution overpotential is 90mV, exhibiting excellent overall anode working characteristics.

[0163] The anode of Example 6 showed no obvious corrosion after 1000 hours of salt spray testing, with a hydrogen evolution overpotential of 85mV and an oxygen evolution overpotential of 225mV, making it suitable for combined corrosion protection and catalysis applications on low-carbon steel substrates.

[0164] The anode of Example 7 exhibited an ultrasonic weight reduction rate of 0.5%. The parameter design adapted to titanium alloys effectively reduced interfacial stress, and the coating showed no cracking after 50 cycles of thermal cycling (-50℃ to 150℃). The hydrogen evolution overpotential was 82mV, and the oxygen evolution overpotential was 252mV, demonstrating excellent stability in titanium alloy substrate applications such as aerospace.

[0165] The anode of Example 8 had a hydrogen evolution overpotential of 70mV and an oxygen evolution overpotential of 230mV. After 800 hours of continuous operation, the decay rate was only 2.8%, and the ultrasonic weight loss rate was 0.43%. Both physical stability and catalytic activity were significantly improved.

[0166] In Example 9, the coating thickness uniformity deviation of the anode was controlled within 5% under high powder feeding rates, improving preparation efficiency. The hydrogen evolution overpotential was 95mV, the oxygen evolution overpotential was 265mV, and the ultrasonic weight loss rate was 0.72%, meeting the efficiency and performance balance requirements for mass production.

[0167] The anode of Example 10, with its low carrier gas flow rate scheme, reduced preparation costs by 18%. The hydrogen evolution overpotential was 130 mV, the oxygen evolution overpotential was 290 mV, the decay rate after 300 hours of continuous operation was 6.7%, and the ultrasonic weight loss rate was 0.94%, demonstrating practical value in the cost-sensitive civilian catalysis field.

[0168] The anode of Comparative Example 1 showed an ultrasonic weight loss rate of 3.2%, and the overpotential was significantly higher than that of Example 1. This is because the absence of the Ni-Cr underlayer prevented the mitigation of the thermal expansion difference between the substrate and the functional layer, leading to interfacial stress concentration, a significant decrease in bonding strength, and impact on the stability of catalytic performance.

[0169] In Comparative Example 2, the hydrogen evolution overpotential rose to 180 mV, which is 100 mV higher than that in Example 1; the performance degradation rate reached 8.5% in the 500-hour stability test, and the hydrogen production per unit time decreased by 30%. The absence of the intermediate layer caused the hydrogen evolution catalytic activity to lose its support, and it could not form a synergy with the oxygen evolution function of the surface layer, resulting in a significant reduction in the overall electrolysis efficiency.

[0170] In Comparative Example 3, the oxygen evolution overpotential of the anode reached as high as 420mV. After operating in a strongly alkaline environment for 300 hours, severe oxidation and corrosion occurred on the surface of the intermediate layer. This demonstrates that the noble metal doping oxide on the surface layer is crucial for reducing the oxygen evolution overpotential. Without the surface layer, the oxygen evolution reaction at the anode is hindered, and the corrosion resistance of the intermediate layer is insufficient, affecting its service life.

[0171] The anode of Comparative Example 4 exhibited an ultrasonic weight loss rate of 1.9%, with a bonding strength between that of Example 1 and Comparative Example 1. Its hydrogen evolution overpotential was 140 mV and its oxygen evolution overpotential was 340 mV, both higher than those of Example 1. After 400 hours, its performance degradation rate reached 7.2%. The single-layer structure cannot achieve functional zoning optimization, making it difficult to simultaneously meet the requirements for bonding strength, hydrogen evolution activity, and oxygen evolution efficiency. Its synergistic performance is far inferior to that of the gradient composite structure.

[0172] The anode of Comparative Example 5 showed an ultrasonic weight loss rate of 0.95%, which was 0.63% higher than that of Example 1; microcracks appeared after 20 cycles of thermal cycling (-50°C to 150°C); and the attenuation rate was 6.8% after 500 hours of stability testing. The pure nickel underlayer was far less effective than the Ni-Cr alloy in mitigating thermal expansion differences and could not effectively disperse interfacial stress, resulting in coating stability and adhesion that were inferior to the original gradient design.

[0173] Compared with the anode of Comparative Example 6, the ultrasonic weight loss rate was 1.75%; the hydrogen evolution overpotential was 110 mV, and the oxygen evolution overpotential was 310 mV; after 350 hours of continuous operation, the performance degradation rate was 9.2%. Insufficient power led to incomplete powder melting, resulting in a decrease in coating density and adhesion.

[0174] Compared with the anode of Comparative Example 7, the ultrasonic weight loss rate was 1.2%; the hydrogen evolution overpotential was 105mV, the oxygen evolution overpotential was 270mV, and the stability decay rate after 500 hours was 7.6%. Excessive power caused the substrate to be overheated, the interfacial stress surged, and the coating was prone to cracking and peeling. Although the density was slightly improved, the thermal damage offset the advantages of catalytic performance and the overall stability decreased.

[0175] The anode of Comparative Example 8 had a hydrogen evolution overpotential of 110 mV and an oxygen evolution overpotential of 265 mV, with a decay rate of 8.1% after 400 hours of continuous operation. Insufficient powder feeding rate resulted in incomplete coating coverage and uneven thickness, reducing the number of active sites. This affected the consistency of catalytic performance, weakened the coating's protective effect on the substrate, and decreased stability.

[0176] Compared with the anode of Comparative Example 9, the ultrasonic weight loss rate was 1.5%; the hydrogen evolution overpotential was 95mV, the oxygen evolution overpotential was 290mV, and the attenuation rate after 500 hours of stability testing was 8.8%. Excessive powder feeding rate resulted in incomplete powder melting, increased internal defects in the coating, reduced adhesion, and uneven distribution of active ingredients, affecting both catalytic efficiency and corrosion resistance.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An anodizing coating, characterized in that, The coating comprises a base layer, an intermediate layer, and a top layer arranged sequentially. The bottom layer contains Ni and Cr; The intermediate layer contains Ni, Mo, and Zn; The surface layer contains RuO2 and IrO2.

2. The anodic coating as described in claim 1, characterized in that, In the bottom layer, the mass percentage of Ni is 80% and the mass percentage of Cr is 20%. And / or, in the intermediate layer, the mass percentage content of Ni is 60-80%, the mass percentage content of Mo is 15-30%, and the mass percentage content of Zn is 5-15%; And / or, in the surface layer, the mass ratio of RuO2 to IrO2 is (1-3):(1-3).

3. An anode, characterized in that, The anode includes a substrate and a coating applied to the surface of the substrate, the coating being the coating as described in any one of claims 1-2.

4. The method for preparing the anode as described in claim 3, characterized in that, The method includes the following steps: (1) Pre-treat and preheat the substrate at a temperature of 200-300℃; (2) A base layer, an intermediate layer and a top layer are sequentially sprayed on the surface of the substrate using a plasma spraying process. The base layer is coated with Ni-Cr alloy powder, the intermediate layer is coated with Ni-Mo-Zn alloy, and the top layer is coated with RuO2 and IrO2. (3) The substrate after spraying is subjected to heat treatment and electrochemical activation treatment to obtain the anode; In step (2), the conditions for plasma spraying of the base layer, intermediate layer and surface layer are independent: spraying power of 30-50 kW, powder feeding rate of 20-50 g / min and carrier gas flow rate of 30-50 L / min.

5. The method for preparing the anode as described in claim 4, characterized in that, The pretreatment of the substrate in step (1) includes: sandblasting the substrate, ultrasonic cleaning, and acid washing.

6. The method for preparing the anode as described in claim 5, characterized in that, The pretreatment of the substrate in step (1) is as follows: the substrate is sandblasted with Al2O3 particles, ultrasonically cleaned with acetone, and acid-washed with HCl.

7. The method for preparing the anode as described in claim 4, characterized in that, In step (2), the conditions for plasma spraying the base layer and the intermediate layer are the same; And / or, the spraying power of the plasma spraying process for the surface layer is greater than or equal to the spraying power of the substrate.

8. The method for preparing the anode as described in claim 4, characterized in that, The heat treatment in step (3) is annealing at 400°C for 30-40 minutes in an inert atmosphere.

9. The method for preparing the anode as described in claim 4, characterized in that, The electrochemical activation treatment in step (3) involves applying 2 A / dm to a 6 M KOH solution. 2 Current density treatment for 0.5-1.5 hours.

10. The application of the anode as described in claim 3 in hydrogen production by water electrolysis.

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