Method for efficiently preparing high-performance and high-stability hydrogen production electrode

Abstract

The invention discloses a method for efficiently preparing a high-performance and high-stability hydrogen production electrode and the obtained electrode, and belongs to the technical field of electrode material preparation. According to the method, at least two plasma spray guns arranged front and back are adopted for conducting continuous multi-layer gradient spraying on a nickel net base body for one time, the spray gun at the foremost end is used for spraying a bottom layer through high-nickel low-aluminum Raney nickel powder, and the high binding force with the base body is ensured; a spray gun at the rearmost end is used for spraying low-nickel high-aluminum (binary or multi-element) Raney nickel powder on the surface layer, and a porous high-activity catalyst layer is formed after alkali liquor activation. A spray gun spraying transition layer can be additionally arranged in the middle. According to the preparation method, a gradient structure of'strong combination bottom layer-high activity surface layer 'is constructed through one-time spraying, the contradiction that the binding force and the catalytic activity of a traditional single-layer spraying electrode are difficult to consider at the same time is fundamentally solved, and meanwhile, the production efficiency is greatly improved. The obtained electrode has excellent electrocatalytic activity, structural stability and long service life, and is suitable for hydrogen production through alkaline water electrolysis.

Description

Technical Field

[0001] This invention relates to the field of electrode material preparation technology, specifically a method for efficiently preparing high-performance and high-stability hydrogen production electrodes. Background Technology

[0002] In current alkaline water electrolysis hydrogen production technology, the electrode is one of the core components, and its performance directly affects the hydrogen production efficiency and system stability. At present, the mainstream hydrogen production electrodes usually use pure nickel braided mesh as the substrate, and the catalytic activity of the electrode is improved by coating a layer of catalyst material (such as Raney nickel) on its surface.

[0003] In existing technologies, methods for coating catalysts onto nickel mesh surfaces mainly include electrodeposition, chemical deposition, powder metallurgy sintering, and plasma spraying. Among these, plasma spraying technology has become the mainstream method for preparing electrode meshes because it is suitable for large-area, complex-shaped substrates and can form coatings with good adhesion. A typical plasma spraying process uses a single spray gun to melt catalyst powder (such as Raney nickel alloy powder) in a high-temperature plasma jet and spray it at high speed onto the nickel mesh substrate to form a coating. Subsequently, the coating needs to be activated by an alkaline solution (such as NaOH solution) to dissolve the aluminum component, forming an active Raney nickel catalyst layer with a high specific surface area and porous structure.

[0004] However, existing single-gun plasma spraying processes have the following inherent drawbacks: when spraying Raney nickel catalysts, the composition of the coating (nickel-aluminum ratio) directly affects the performance of the final electrode. If Raney nickel powder with high aluminum content is used, after activation with alkaline solution, a large amount of aluminum is dissolved, resulting in a coating with many pores, a large specific surface area, and high catalytic activity. However, due to the weak bonding interface between the metallic nickel skeleton and the nickel mesh substrate in the coating, under the stress generated by frequent start-ups and shutdowns or long-term operation of the hydrogen production system, the coating is prone to peeling off from the substrate, leading to electrode deactivation and shortened lifespan.

[0005] Conversely, if Raney nickel powder with high nickel content is used, the coating has strong adhesion to the nickel mesh substrate and good stability, but the pore structure formed after activation is underdeveloped and there are few active sites, resulting in low catalytic activity of the electrode and poor hydrogen production efficiency.

[0006] Therefore, existing technologies struggle to achieve a good balance between "high catalytic activity" and "high binding force / stability" in electrodes. Summary of the Invention

[0007] The purpose of this invention is to provide a method for efficiently preparing high-performance and high-stability hydrogen production electrodes, so as to solve the existing technical problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for efficiently preparing a high-performance, high-stability hydrogen production electrode, comprising the following steps:

[0009] A Raney nickel catalyst coating is applied to a nickel mesh substrate using a multi-gun plasma spraying system; the multi-gun plasma spraying system is equipped with at least two plasma spray guns arranged one in front of the other along the spraying direction.

[0010] The spraying process involves multi-layer gradient spraying, specifically including:

[0011] The first catalyst coating is applied to the nickel mesh substrate using a plasma spray gun at the very front end. The powder used for the first catalyst coating is a high-nickel, low-aluminum Raney nickel alloy powder, wherein the mass ratio of nickel to aluminum is (85~95):(15~5).

[0012] The outermost catalyst coating is sprayed onto the surface of the first catalyst coating using a plasma spray gun at the very end. The powder used for the outermost catalyst coating is a low-nickel, high-aluminum Raney nickel alloy powder, wherein the mass ratio of nickel to aluminum is (40~75):(60~25).

[0013] The multi-layer gradient spraying is completed in a single continuous spraying process;

[0014] After the coating is completed, the electrode mesh with the gradient coating is subjected to alkaline activation treatment to dissolve the aluminum component in the coating, thereby obtaining the hydrogen generation electrode.

[0015] Furthermore, the multi-gun plasma spraying system is provided with three or more plasma spray guns arranged in a front-to-back manner along the spraying direction; between the first layer and the outermost layer, at least one intermediate transition layer catalyst coating is sprayed using at least one plasma spray gun located in the middle; the mass ratio of nickel to aluminum in the sprayed powder used for the intermediate transition layer is between the nickel-aluminum mass ratio of the first layer and the outermost layer.

[0016] Furthermore, the low-nickel, high-aluminum Raney nickel alloy powder is a binary Ni-Al alloy powder or a multi-element alloy powder.

[0017] The multi-element alloy powder is selected from one or more combinations of Ni-Al-Mo, Ni-Al-Cr, Ni-Al-Fe, and Ni-Al-Co, wherein the total mass percentage of nickel is 40% to 75%.

[0018] Furthermore, when the low-nickel, high-aluminum Raney nickel alloy powder is a binary alloy powder, the mass ratio of nickel to aluminum is 70:30.

[0019] Furthermore, when the low-nickel, high-aluminum Raney nickel alloy powder is a Ni-Al-Mo ternary alloy powder, the mass ratio of nickel, molybdenum, and aluminum is 50:20:30.

[0020] Furthermore, the alkaline solution used in the alkaline activation treatment is a NaOH or KOH solution with a concentration of 4-8 mol / L, the treatment temperature is 60-90℃, and the treatment time is 1-4 hours.

[0021] In another aspect, the present invention provides a hydrogen production electrode prepared according to the above method.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention, through a gradient design of "high nickel and low aluminum in the bottom layer, and low nickel and high aluminum in the surface layer," ensures excellent metallurgical adhesion between the coating and the nickel mesh substrate in the bottom layer, providing strong support for the entire coating and significantly improving the electrode's resistance to peeling and long-term operational stability. The surface layer, after activation, forms a well-developed porous structure, exposing abundant catalytic active sites, thereby endowing the electrode with high catalytic activity and hydrogen production efficiency. This invention resolves the contradiction between adhesion and activity through structural design.

[0024] 2. This invention employs a multi-spray gun parallel / front-and-back arrangement design, where powders of different compositions are simultaneously or sequentially delivered by their respective independent spray guns. The substrate only needs to pass through the spraying area once to complete the construction of a multi-layer gradient coating. Compared to traditional methods requiring multiple round trips with a single spray gun to achieve a gradient effect, this invention significantly improves production efficiency and simplifies the process.

[0025] 3. This invention offers a controllable and flexible structure: By adjusting the number and arrangement of spray guns, as well as the composition of the powder delivered by each gun, the gradient composition, number of layers, and thickness of each layer of the coating can be designed and controlled flexibly and precisely to meet different performance requirements. For example, adding an intermediate transition layer can make the composition gradient smoother, further improving interlayer stress and enhancing overall bonding strength.

[0026] 4. This invention offers high equipment utilization: the multi-spray gun system can select single-spray gun, dual-spray gun, or multi-spray gun combination working modes according to production needs, making it more adaptable. Detailed Implementation

[0027] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1

[0030] This embodiment provides a method for preparing a hydrogen production electrode using a dual-spray gun plasma spraying system.

[0031] 1. Substrate preparation: The pure nickel braided mesh (100 mesh) is sandblasted to roughen it, and then cleaned and dried with ethanol.

[0032] 2. Spraying Equipment and Powder: A self-modified dual-spray gun plasma spraying system was used. The two spray guns were arranged back-to-back along the horizontal conveying direction of the nickel mesh, with adjustable spacing. Two types of atomized spherical Raney nickel alloy powders were prepared: Powder A (high nickel, low aluminum type), with a nickel-aluminum mass ratio of 90:10 and a particle size range of 45-90 μm; Powder B (low nickel, high aluminum type), with a nickel-aluminum mass ratio of 70:30 and a particle size range of 45-90 μm.

[0033] 3. Gradient Spraying: The nickel mesh substrate is horizontally and uniformly passed through the spraying area of ​​the dual spray guns. When the front spray gun (gun 1) passes the substrate, powder A is fed in, forming a bottom bonding layer on the nickel mesh surface. Key process parameters: Ar / H2 mixed plasma gas, 550A current, 70V voltage, spraying distance 120mm. When the same substrate area moves to below the rear spray gun (gun 2), powder B is fed in, spraying a surface active layer on the newly formed bottom layer. Key process parameters are similar to those of gun 1 and can be fine-tuned according to powder characteristics. By controlling the substrate moving speed and powder feeding rate, the bottom layer thickness is approximately 50μm, and the surface layer thickness is approximately 80μm.

[0034] 4. Activation Treatment: The coated electrode mesh was immersed in a 6 mol / L NaOH solution and kept at 80℃ for 2 hours. It was then repeatedly rinsed with deionized water until neutral and dried to obtain the finished hydrogen production electrode. Testing showed that the electrode coating had strong adhesion, and the activated surface exhibited a porous, sponge-like structure. Electrolysis tests were conducted under conditions of 30% KOH, 80℃, and a current density of 400 mA / cm². The hydrogen evolution overpotential was significantly lower than that of a traditional single-layer coated electrode (nickel-aluminum ratio 80:20), and after 500 start-stop cycles, no visible peeling of the coating was observed, with a performance degradation rate of <5%.

[0035] Example 2

[0036] This embodiment provides a method for preparing a hydrogen production electrode using a three-spray gun plasma spraying system.

[0037] 1. Substrate preparation: Same as in Example 1.

[0038] 2. Spraying Equipment and Powder: A three-gun plasma spraying system is used, with the three guns arranged in a front-to-back pattern. Three types of alloy powders are prepared: Powder C (high-nickel, low-aluminum type), with a nickel-aluminum mass ratio of 90:10; Powder D (medium-nickel, medium-aluminum type), with a nickel-aluminum mass ratio of 80:20; and Powder E (low-nickel, high-aluminum, multi-element type), with a nickel:molybdenum:aluminum mass ratio of 50:20:30. The particle size of all powders is 45-75 μm.

[0039] 3. Gradient spraying:

[0040] The nickel mesh substrate passes through the spraying zone at a uniform speed.

[0041] When passing through gun 1, powder C is fed in to form a bottom layer (approximately 30 μm).

[0042] When passing through gun 2, powder D is fed in to form an intermediate transition layer (approximately 40 μm).

[0043] When passing through gun 3, powder E is fed in to form a surface layer (approximately 60 μm).

[0044] The plasma process parameters for each gun are independently optimized to ensure that each layer is fully melted and densely deposited.

[0045] 4. Activation treatment: The same alkaline activation process as in Example 1 is used.

[0046] The resulting electrode exhibits a gentler compositional gradient and better interlayer bonding. Electrochemical tests show that its catalytic activity is comparable to that of Example 1, but it demonstrates superior durability with a smaller voltage rise during 1000-hour long-term stability testing.

[0047] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for efficiently preparing a high-performance, high-stability hydrogen production electrode, characterized in that, Includes the following steps: A Raney nickel catalyst coating was applied to a nickel mesh substrate using a multi-gun plasma spraying system. The multi-gun plasma spraying system is equipped with at least two plasma spray guns arranged one in front of the other along the spraying direction. The spraying process involves multi-layer gradient spraying, specifically including: The first catalyst coating is applied to the nickel mesh substrate using a plasma spray gun at the very front end. The powder used for the first catalyst coating is a high-nickel, low-aluminum Raney nickel alloy powder, wherein the mass ratio of nickel to aluminum is (85~95):(15~5). The outermost catalyst coating is sprayed onto the surface of the first catalyst coating using a plasma spray gun at the very end. The powder used for the outermost catalyst coating is a low-nickel, high-aluminum Raney nickel alloy powder, wherein the mass ratio of nickel to aluminum is (40~75):(60~25). The multi-layer gradient spraying is completed in a single continuous spraying process; After the coating is completed, the electrode mesh with the gradient coating is subjected to alkaline activation treatment to dissolve the aluminum component in the coating, thereby obtaining the hydrogen generation electrode.

2. The method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 1, characterized in that: The multi-gun plasma spraying system has three or more plasma spray guns arranged in a front-to-back direction along the spraying direction; between the first layer and the outermost layer, at least one intermediate transition layer catalyst coating is sprayed using at least one plasma spray gun located in the middle; the mass ratio of nickel to aluminum in the sprayed powder used for the intermediate transition layer is between the nickel-aluminum mass ratio of the first layer and the outermost layer.

3. A method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 1 or 2, characterized in that: The low-nickel, high-aluminum Raney nickel alloy powder is a binary Ni-Al alloy powder or a multi-element alloy powder. The multi-element alloy powder is selected from one or more combinations of Ni-Al-Mo, Ni-Al-Cr, Ni-Al-Fe, and Ni-Al-Co, wherein the total mass percentage of nickel is 40% to 75%.

4. The method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 1, characterized in that: The mass ratio of nickel to aluminum in the high-nickel, low-aluminum Raney nickel alloy powder is 90:

10.

5. A method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 1 or 3, characterized in that: When the low-nickel, high-aluminum Raney nickel alloy powder is a binary alloy powder, the mass ratio of nickel to aluminum is 70:

30.

6. The method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 3, characterized in that: When the low-nickel, high-aluminum Raney nickel alloy powder is a Ni-Al-Mo ternary alloy powder, the mass ratio of nickel, molybdenum, and aluminum is 50:20:

30.

7. The method for efficiently preparing a high-performance, high-stability hydrogen production electrode according to claim 1, characterized in that: The alkaline activation treatment uses a NaOH or KOH solution with a concentration of 4-8 mol / L, a treatment temperature of 60-90℃, and a treatment time of 1-4 hours.

8. A hydrogen production electrode, characterized in that, Prepared by the method according to any one of claims 1 to 7.