Multilayer nickel mesh catalytic electrode for alkaline water electrolysis to produce hydrogen and preparation method thereof

Abstract

The present invention relates to a multi-layer nickel mesh catalytic electrode for producing hydrogen by alkaline electrolysis of water and a preparation method thereof. The multi-layer catalytic electrode comprises multiple layers of nickel meshes with different mesh sizes, which are stacked in order from large to small in mesh size and sintered to form a multi-layer nickel mesh catalytic electrode with a dense inner layer and a sparse outer layer. The preparation method comprises stacking the nickel meshes with different mesh sizes in order from large to small in mesh size and sintering them; then laying the raw tape on the outer surface of the first layer of nickel mesh, performing stamping and electrodeposition, polishing after electrodeposition, and then rapidly sintering to obtain the multi-layer catalytic electrode. Compared with the prior art, the catalytic electrode of the present invention has a three-layer nickel mesh structure with a dense inner layer and a sparse outer layer, and adopts a vacuum sintering process to slightly melt and bond the three layers of nickel mesh together at high temperature to form an integral structure, which not only enhances the bonding force between the nickel meshes, but also retains the characteristics of each layer of nickel mesh, effectively solving the shortcomings of the single-layer nickel mesh in terms of catalyst loading, mass transfer performance and mechanical strength.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic electrodes, and in particular to a multi-layer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis and a preparation method thereof. Background Art

[0002] Hydrogen production from water electrolysis is a key area of ​​research in the energy sector. As a clean, renewable energy source, it holds broad promise for application in the hydrogen energy industry. However, the efficiency and cost of this technology are significantly impacted by the performance of the electrodes in the electrolyzer. As key components in the electrochemical reaction, the material and structure of the electrodes play a decisive role in determining electrolysis efficiency, energy consumption, and service life.

[0003] Existing electrodes for water electrolysis mainly use a single-layer nickel mesh structure. This single-layer nickel mesh has many problems and shortcomings in terms of catalyst loading, mass transfer performance, and mechanical strength. First, the single-layer nickel mesh has the problem of unstable catalyst loading. During the electrodeposition process, the catalyst easily adheres to the surface of the nickel mesh. However, due to the single-layer structure of the nickel mesh, the bonding force between the catalyst and the substrate is weak, causing the catalyst to easily fall off during the electrolysis process, thereby reducing the catalytic activity and service life of the electrode. In addition, the single-layer nickel mesh is subjected to the scouring of the electrolyte and the mechanical impact of gas generation during use, making the catalyst more likely to fall off, exacerbating the attenuation of electrode activity.

[0004] Secondly, the mass transfer performance of the single-layer nickel mesh is poor. The gases (hydrogen and oxygen) generated during the electrolysis of water need to be quickly discharged from the electrode surface to maintain the efficient conduct of the electrolysis reaction. However, the structure of the single-layer nickel mesh limits the rapid diffusion and discharge of the gas, causing the gas to gather on the electrode surface, forming a bubble layer, which hinders the contact between the electrolyte and the electrode, thereby reducing the active area of ​​the electrode and the electrolysis efficiency. This problem of poor gas mass transfer is particularly prominent at high current density, seriously affecting the overall performance of hydrogen production by electrolysis of water.

[0005] In addition, the catalyst attached to the surface of the nickel mesh will affect the contact resistance of the electrode when assembled into the electrolytic cell. Good electrical contact is required between the electrode and other components of the electrolytic cell to ensure effective current transfer and efficient electrolysis reaction. However, the catalyst deposited on the surface of the single-layer nickel mesh electrode often makes the electrode surface rough, increasing the contact resistance, affecting the current transmission efficiency, and thus increasing the energy consumption during the electrolysis process. At the same time, the uneven catalyst layer on the electrode surface may also lead to uneven current distribution, further reducing the electrolysis efficiency and the service life of the electrode.

[0006] Furthermore, existing single-layer nickel mesh electrodes also lack mechanical strength and durability. The thin structure of the single-layer nickel mesh makes it susceptible to deformation or damage during prolonged, high-intensity electrolysis, impacting the electrode's stability and service life. This lack of mechanical strength also limits its application in high-current density and complex electrolysis environments, reducing its applicability and reliability.

[0007] Therefore, existing single-layer nickel mesh electrodes have significant limitations in catalyst loading, mass transfer performance, electrical contact, current distribution, and mechanical strength, making them unable to meet the requirements for efficient and stable hydrogen production from water electrolysis. Therefore, there is an urgent need to develop a new electrode structure to improve the electrode's catalytic activity, mass transfer performance, and mechanical strength, and reduce contact resistance, thereby achieving efficient and stable application of water electrolysis hydrogen production technology. Summary of the Invention

[0008] The present invention aims to overcome the shortcomings of the prior art by providing a multilayer nickel mesh catalytic electrode for hydrogen production by alkaline water electrolysis and a method for its preparation. By stacking and sintering nickel meshes of varying mesh sizes, a dense inner and loose outer structure is formed, effectively improving the overall mechanical strength and stability of the electrode.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The present invention provides a multi-layer catalytic electrode for producing hydrogen by alkaline electrolysis of water, wherein the multi-layer catalytic electrode comprises a first layer of nickel mesh, a second layer of nickel mesh, and a third layer of nickel mesh having different mesh sizes;

[0011] The first layer of nickel mesh, the second layer of nickel mesh and the third layer of nickel mesh are stacked in order from large to small in mesh size and sintered to form a multi-layer nickel mesh catalytic electrode with dense inner layer and sparse outer layer.

[0012] Furthermore, the second layer of nickel mesh is loaded with a catalyst.

[0013] Furthermore, the mesh number of the first layer of nickel mesh is 100-300 mesh, the mesh number of the second layer of nickel mesh is 30-100 mesh, and the mesh number of the third layer of nickel mesh is 10-30 mesh.

[0014] The present invention also provides a method for preparing a multilayer catalytic electrode for producing hydrogen by alkaline water electrolysis, comprising the following steps:

[0015] S1: stacking nickel meshes of different mesh sizes in descending order, and placing them in a vacuum sintering furnace for sintering to obtain a sintered three-layer nickel mesh;

[0016] S2: Laying the raw tape on the outer surface of the first layer of the three-layer nickel mesh sintered in S1, and stamping it to obtain a three-layer nickel mesh with the raw tape;

[0017] S3: The three-layer nickel mesh with the raw tape in S2 is immersed in the electroplating solution for electrodeposition using a pulse current. After the electrodeposition is completed, the raw tape is torn off, and the surface of the third layer of nickel mesh is polished, and then quickly sintered to obtain a multi-layer catalytic electrode.

[0018] Furthermore, in S1, the sintering temperature is 800-1100° C., and the sintering time is 3-5 hours; preferably, the sintering temperature is 900° C., and the sintering time is 4 hours.

[0019] Furthermore, in S2, the size of the raw tape is the same as the size of the first layer of nickel mesh.

[0020] Furthermore, in S3, the electroplating solution includes nickel chloride, ammonium chloride, boric acid and ammonia water, the concentration of the nickel chloride is 0.05-0.5M, and the concentration of the ammonium chloride is 1-4M; preferably, the concentration of the nickel chloride is 0.2M, and the concentration of the ammonium chloride is 2M.

[0021] Furthermore, in S3, the electroplating time is 5-30 minutes, the current density is 0.5-5A, and the frequency of the pulse current is 0.1-10Hz; preferably, the electroplating time is 15 minutes, the current density is 2A, and the frequency of the pulse current is 1Hz.

[0022] Furthermore, in S3, the rapid sintering conditions are: a sintering temperature of 600-1000° C., and a sintering time of 10-30 seconds; preferably, the sintering temperature is 800° C., and the sintering time is 20 seconds.

[0023] Furthermore, in S2, the raw tape is polytetrafluoroethylene, which is used to prevent the electroplating solution from contacting the surface of the first layer of nickel mesh, thereby avoiding the deposition of catalyst on the surface of the first layer of nickel mesh.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. The catalytic electrode in the present invention has a three-layer nickel mesh with a dense inner and sparse outer structure, which effectively improves the overall mechanical strength and stability of the electrode. The first layer of nickel mesh is attached to the diaphragm, which can prevent the diaphragm from being pierced by the electrode, thereby protecting the diaphragm; the second layer of nickel mesh has a moderate mesh size, which can load a large amount of catalyst, and can significantly improve the catalytic activity of the electrode. The catalyst is protected between the first layer of nickel mesh and the third layer of nickel mesh, which effectively prevents the catalyst from falling off due to mechanical impact during the electrolysis process, thereby extending the service life of the electrode. The third layer of nickel mesh has a smaller mesh size and sparse mesh, which is conducive to gas diffusion and mass transfer, reduces the problem of bubble aggregation on the electrode surface, and improves the gas discharge efficiency during the electrolysis process, thereby further improving the efficiency of hydrogen production by electrolysis of water.

[0026] 2. The present invention adopts a vacuum sintering process, which allows the three layers of nickel mesh to be slightly melted and bonded together at high temperature to form an integral structure. This not only enhances the bonding force between the nickel meshes, but also retains the characteristics of each layer of nickel mesh, achieving a multi-layer structure with dense inner and sparse outer layers, effectively solving the shortcomings of single-layer nickel mesh in catalyst loading, mass transfer performance and mechanical strength.

[0027] 3. The present invention uses pulsed current to electrodeposit the catalyst. By applying intermittent current, the ions consumed in the reaction zone are replenished, ensuring that the intermediate nickel mesh can be fully electrodeposited with catalyst, significantly improving the effectiveness of the electrodeposition process and the catalytic activity of the electrode. By covering the first layer of nickel mesh with raw tape, the electroplating solution is prevented from contacting its surface, preventing catalyst deposition on the first layer of nickel mesh, ensuring low contact resistance when the electrode is assembled in the electrolytic cell. After sandpaper polishing and rapid sintering, the surface of the third layer of nickel mesh is smoothed, reducing the contact resistance between the electrode and other components of the electrolytic cell, further improving current transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of an assembly method of a multi-layer nickel mesh catalytic electrode for alkaline water electrolysis in Example 1;

[0029] Figure 2 Schematic diagram of the structure of the original three-layer nickel mesh in Example 1;

[0030] Figure 3 Schematic diagram of the structure of the three-layer nickel mesh merged into a whole after sintering in Example 1;

[0031] Figure 4 Schematic diagram of the structure of the three-layer nickel mesh covering the raw tape in Example 1;

[0032] Figure 5 This is a schematic diagram of the structure of the three-layer nickel mesh with the raw tape removed after electroplating in Example 1;

[0033] Figure 6 Schematic diagram of the structure of the nickel mesh after the catalyst on the third layer of the nickel mesh surface is polished off in Example 1;

[0034] Figure 7 This is a SEM image of the catalyst material on the surface of the multilayer catalytic electrode before sintering in Example 1;

[0035] Figure 8 This is a SEM image of the catalyst material on the surface of the multi-layer catalytic electrode after sintering in Example 1;

[0036] Figure 9 Graph showing polarization curves of water electrolysis of the multilayer catalytic electrode and the common nickel mesh electrode prepared in Example 1.

[0037] Description of the markings in the figure:

[0038] 1-diaphragm, 2-first layer of nickel mesh, 3-second layer of nickel mesh, 4-third layer of nickel mesh, 5-electrolytic cell plate, 6-raw tape. DETAILED DESCRIPTION

[0039] The specific implementation methods of the present invention are described in detail below through examples. These examples are implemented under the premise of the scheme described in the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following examples.

[0040] The present invention is further described below with reference to the accompanying drawings and specific embodiments. Any features, such as component models, material names, connection structures, preparation methods, materials, structures, or composition ratios, that are not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0041] Example 1

[0042] This embodiment provides a method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis, comprising the following steps:

[0043] S1: Select three-layer nickel mesh, such as Figure 2 As shown in the figure, the first layer of nickel mesh 2 has a mesh count of 200, dense meshes, and a relatively smooth surface; the second layer of nickel mesh 3 has a mesh count of 60, with medium mesh density; the third layer of nickel mesh 4 has a mesh count of 20, with sparse meshes. The three layers of nickel mesh are stacked in sequence, arranged in descending order of mesh count, to form a multi-layer structure with dense inner and sparse outer layers, and then placed in a vacuum sintering furnace for sintering at a temperature of 900°C for 4 hours. The high temperature causes the surfaces of the three layers of nickel mesh to melt slightly and stick together to form an integral multi-layer nickel mesh structure, as shown in the figure. Figure 3 This sintering process not only forms a strong bond between the nickel meshes, but also preserves the characteristics of each layer of nickel mesh, thus achieving a dense inner and sparse outer structure.

[0044] S2: Since the mesh size of the first layer of nickel mesh 2 is large and the surface is relatively smooth and flat, it can contact the diaphragm and play a role in protecting the diaphragm. Therefore, in order to prevent the surface of the first layer of nickel mesh 2 from being electroplated with catalyst, a raw tape 6 is laid on the surface of the first layer of nickel mesh 2. As a material with good ductility, the raw tape 6 can fit tightly with the surface of the nickel mesh after stamping, thereby effectively preventing the electroplating solution from contacting the surface of the first layer of nickel mesh 2 and avoiding the deposition of catalyst on the surface. The material is polytetrafluoroethylene. Cut the raw tape 6 into the same size as the first layer of nickel mesh 2, and lay it flat on the outer surface of the first layer of nickel mesh 2 in the three-layer nickel mesh sintered in S1. Use a punching machine to stamp it to ensure that the raw tape 6 fits tightly with the surface of the nickel mesh to prevent the electroplating solution from contacting the side surface, and obtain a three-layer nickel mesh with raw tape 6, such as Figure 4 As shown;

[0045] S3: Prepare an electroplating solution with 0.2M nickel chloride, 2M ammonium chloride, 0.5M boric acid, and an appropriate amount of ammonia water. Immerse the three-layer nickel mesh with the raw tape 6 in S2 in the electroplating solution. Electrodeposition is performed using a pulsed current with a current density of 2A, an electroplating time of 15 minutes, and a pulse frequency of 1Hz. The pulsed current is applied intermittently to fully replenish ions. Catalysts are fully electroplated on the second and third nickel meshes 3 and 4, improving the catalytic activity of the electrodes. After the electroplating is completed, the raw tape 6 is removed. Figure 5 shown.

[0046] S4: polish the surface of the third layer of nickel mesh 4 that has been electro-deposited in S3 to remove the catalyst deposited on the surface, make the surface smooth, and reduce the contact resistance when assembled into the electrolytic cell, such as Figure 6 As shown, the three-layer nickel mesh electrode is rapidly sintered at a sintering temperature of 800° C. and a sintering time of 20 seconds to obtain a multi-layer nickel mesh catalytic electrode.

[0047] By rapid sintering, the catalyst deposited on the second layer of nickel mesh 3 is quickly solidified, thereby improving the mechanical strength and stability of the electrode. The grain state of the multi-layer nickel mesh catalytic electrode before sintering and the multi-layer nickel mesh catalytic electrode after sintering is shown in FIG. Figure 7 and Figure 8 The catalyst is a porous nickel material loaded on the surface of the nickel mesh during the electrodeposition process, that is, a metallic nickel element with a micro-nano structure having a high specific surface area.

[0048] Electrode assembly as Figure 1 As shown, the multilayer catalytic electrode prepared in this embodiment includes a diaphragm 1, a prepared multilayer catalytic electrode and an electrolytic cell plate 5. The obtained multilayer catalytic electrode is subjected to an alkaline water electrolysis test at a test temperature of 80°C and an electrolyte of 30 wt.% KOH. The cathode and anode both use the multilayer nickel mesh catalytic electrode prepared in this embodiment. The results are shown in FIG. Figure 9 As shown in the figure, it can be seen that compared with the commercial nickel mesh, the multi-layer nickel mesh catalytic electrode prepared in this embodiment has lower power consumption during the water electrolysis process.

[0049] Comparative Example 1

[0050] This comparative example uses a commercial nickel mesh with a wire diameter of 0.15 mm, a mesh size of 50, and a nickel metal purity of 99.5%. The commercial nickel mesh is subjected to an alkaline water electrolysis test at a test temperature of 80°C, an electrolyte of 30% wt. KOH, and commercial nickel meshes for both the cathode and the anode. The results are shown in FIG. Figure 9 shown.

[0051] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis, characterized in that: The multi-layer nickel mesh catalytic electrode comprises a first layer of nickel mesh (2), a second layer of nickel mesh (3) and a third layer of nickel mesh (4) having different mesh sizes; The first layer of nickel mesh (2), the second layer of nickel mesh (3) and the third layer of nickel mesh (4) are stacked in descending order of mesh size and sintered to form a multi-layer nickel mesh catalytic electrode with dense inner and sparse outer meshes; The second layer of nickel mesh (3) is loaded with a catalyst.

2. A multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: The mesh number of the first layer of nickel mesh (2) is 100-300 meshes, the mesh number of the second layer of nickel mesh (3) is 30-100 meshes, and the mesh number of the third layer of nickel mesh (4) is 10-30 meshes.

3. A method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: stacking nickel meshes of different mesh sizes in descending order, and placing them in a vacuum sintering furnace for sintering to obtain a sintered three-layer nickel mesh; S2: Laying the raw tape (6) on the outer surface of the first layer of nickel mesh (2) in the three-layer nickel mesh sintered in S1, and stamping it to obtain a three-layer nickel mesh with the raw tape (6); S3: The three-layer nickel mesh with the raw tape (6) in S2 is immersed in the electroplating solution for electroplating using a pulse current. After the electroplating is completed, the raw tape (6) is torn off, and the surface of the third layer of nickel mesh (4) is polished, and then rapidly sintered to obtain a multi-layer catalytic electrode.

4. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, wherein: In S1, the sintering temperature is 800-1100° C., and the sintering time is 3-5 hours.

5. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, characterized in that: In S2, the size of the raw tape (6) is the same as the size of the first layer of nickel mesh (2).

6. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, characterized in that: In S3, the electroplating solution includes nickel chloride, ammonium chloride, boric acid and ammonia water, the concentration of the nickel chloride is 0.05-0.5M, and the concentration of the ammonium chloride is 1-4M.

7. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, characterized in that: In S3, the electroplating time is 5-30 minutes, the current density is 0.5-5 A, and the frequency of the pulse current is 0.1-10 Hz.

8. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, characterized in that: In S3, the rapid sintering conditions are: sintering temperature of 600-1000° C., and sintering time of 10-30 seconds.

9. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 3, characterized in that: In S2, the raw tape (6) is polytetrafluoroethylene, which is used to prevent the electroplating solution from contacting the surface of the first layer of nickel mesh (2) and avoid the catalyst from being deposited on the surface of the first layer of nickel mesh (2).

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