Multi-layer nickel net catalytic electrode for hydrogen production by alkaline electrolysis of water and preparation method of multi-layer nickel net catalytic electrode

Abstract

The invention relates to a multi-layer nickel net catalytic electrode for hydrogen production by alkaline electrolysis of water and a preparation method of the multi-layer nickel net catalytic electrode. The multi-layer catalytic electrode comprises multiple layers of nickel nets with different mesh numbers, and the multiple layers of nickel nets are sequentially stacked according to the mesh numbers from large to small and are sintered and formed to form the multi-layer nickel net catalytic electrode with the dense inside and the sparse outside. The preparation method comprises the following steps: sequentially stacking nickel nets with different mesh numbers according to the mesh number from large to small, and sintering; and then a raw material belt is flatly laid on the outer surface of the first layer of nickel net, stamping and electro-deposition are carried out, polishing is carried out after electro-deposition, rapid sintering is carried out, and the multi-layer catalytic electrode is obtained. Compared with the prior art, the catalytic electrode disclosed by the invention is of a structure with three layers of nickel nets which are dense inside and sparse outside, and the three layers of nickel nets are slightly melted and adhered together at high temperature to form an integral structure by adopting a vacuum sintering process, so that not only is the binding force among the nickel nets enhanced, but also the characteristics of each layer of nickel net are retained; the defects of a single-layer nickel net in the aspects of catalyst loading, mass transfer performance and mechanical strength are effectively overcome.

Description

Technical Field

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

[0002] Hydrogen production technology by water electrolysis is one of the current research focuses in the energy field. As a clean and renewable way to produce energy, it has broad application prospects in the hydrogen energy industry. However, the efficiency and cost of hydrogen production technology by water electrolysis are largely affected by the performance of electrodes in the electrolyzer. As the key component for realizing electrochemical reactions in the process of water electrolysis, the material and structure of the electrode play a decisive role in the electrolysis efficiency, energy consumption, service life, etc.

[0003] The existing electrodes for electrolyzing water mainly adopt 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 is easily attached to the surface of the nickel mesh, but 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 shock of gas generation during use, making the catalyst more likely to fall off, aggravating the attenuation of the 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 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 to form 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, which seriously affects 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 transfer of current and efficient electrolysis reaction. However, the catalyst deposited on the surface of the single-layer nickel mesh electrode often makes the electrode surface rough, increases the contact resistance, affects the current transmission efficiency, and thus increases 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] In addition, the existing single-layer nickel mesh electrode also has deficiencies in mechanical strength and durability. The structure of the single-layer nickel mesh is relatively thin, and it is easy to deform or damage during long-term, high-intensity electrolysis, affecting the stability and service life of the electrode. The lack of mechanical strength of the electrode also limits its application in high current density and complex electrolysis environments, reducing its applicability and reliability.

[0007] Therefore, the existing single-layer nickel mesh electrode has great limitations in catalyst loading, mass transfer performance, electrical contact, current distribution and mechanical strength, and cannot meet the needs of efficient and stable water electrolysis hydrogen production. Therefore, it is urgent to develop a new electrode structure to improve the catalytic activity, mass transfer performance and mechanical strength of the electrode, reduce the contact resistance, and thus realize the efficient and stable application of water electrolysis hydrogen production technology. Summary of the invention

[0008] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a multi-layer nickel mesh catalytic electrode for hydrogen production by alkaline water electrolysis and a preparation method thereof. By stacking and sintering nickel meshes with different mesh sizes to form a dense inner and sparse outer structure, the overall mechanical strength and stability of the electrode are effectively improved.

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

[0010] The present invention provides a multilayer catalytic electrode for producing hydrogen by alkaline electrolysis of water, the multilayer catalytic electrode comprising 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 and sparse outer layers.

[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 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] Further, 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] Further, 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] Further, 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 conditions for rapid sintering 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 and avoid the catalyst from being deposited 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 is 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 can load a large amount of catalyst due to its moderate mesh size, which can significantly improve the catalytic activity of the electrode, and 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 to slightly melt and stick 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, achieving a multi-layer structure with dense inside and sparse outside, and effectively solving the shortcomings of single-layer nickel mesh in catalyst loading, mass transfer performance and mechanical strength.

[0027] 3. The present invention uses pulse current to electro-deposit catalysts. By applying intermittent current, the ions consumed in the reaction area can be replenished, ensuring that the intermediate layer of nickel mesh can be fully electro-deposited with catalysts, significantly improving the effectiveness of the electro-deposition 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 the catalyst from being deposited on the first layer of nickel mesh, ensuring that the electrode has low contact resistance when assembled in the electrolytic cell. After sandpaper polishing and rapid sintering, the surface of the third layer of nickel mesh is smooth, reducing the contact resistance between the electrode and other parts of the electrolytic cell, and further improving the current transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of an assembly method of a multilayer 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 This is a schematic diagram of the structure of the three-layer nickel mesh combined into a whole after sintering in Example 1;

[0031] Figure 4 This is a 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 torn off after electroplating in Example 1;

[0033] Figure 6 This is a schematic diagram of the structure of the nickel mesh after the catalyst on the surface of the third layer of the nickel mesh 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 multilayer catalytic electrode after sintering in Example 1;

[0036] Fig. 9 The polarization curves of water electrolysis of the multilayer catalytic electrode prepared in Example 1 and the ordinary nickel mesh electrode.

[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 on 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 in conjunction with the accompanying drawings and specific embodiments. Any features such as component models, material names, connection structures, preparation methods, materials, structures or composition ratios not clearly described in this technical solution are deemed 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 a three-layer nickel mesh, such as Figure 2 As shown, 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 one after another, arranged in order from large to small mesh counts, to form a multi-layer structure with dense inner and sparse outer meshes, and 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 FIG. Figure 3 The sintering process not only forms a strong bond between the nickel meshes, but also retains the characteristics of each layer of nickel mesh, thereby achieving a dense inner and sparse outer structural feature.

[0044] S2: Since the first layer of nickel mesh 2 has a large mesh size and a relatively smooth surface, it can contact with 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 electro-deposited 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 stamping 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: 0.2M nickel chloride, 2M ammonium chloride, 0.5M boric acid and appropriate amount of ammonia water are prepared into an electroplating solution, and the three-layer nickel mesh with the raw tape 6 in S2 is immersed in the electroplating solution. Electroplating is performed using a pulse current with a current density of 2A, an electroplating time of 15 minutes, and a pulse frequency of 1Hz. The pulse current is applied by applying an intermittent current so that the ions are fully replenished. The catalyst is fully electroplated on the second layer of nickel mesh 3 and the third layer of nickel mesh 4 to improve the catalytic activity of the electrode. After the electroplating is completed, the raw tape 6 is torn off. Figure 5 shown.

[0046] S4: polish the surface of the third layer of nickel mesh 4 after electrodeposition in S3 to remove the catalyst deposited on the surface, make the surface smooth, and reduce the contact resistance when assembled in the electrolytic cell, such as Figure 6 As shown, the three-layer nickel mesh electrode is quickly sintered at a sintering temperature of 800° C. for 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 rapidly 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 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, an electrolyte of 30 wt.% KOH, and the cathode and anode are both multilayer nickel mesh catalytic electrodes prepared in this embodiment. The results are shown in FIG. Fig. 9 As shown in the figure, it can be seen that compared with the commercial nickel mesh, the multilayer 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 are used for both the cathode and the anode. The results are shown in FIG. Fig. 9 shown.

[0051] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 order from large to small mesh sizes and sintered to form a multi-layer nickel mesh catalytic electrode with dense inner and sparse outer meshes.

2. A multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 1, characterized in that: The second layer of nickel mesh (3) is loaded with a catalyst.

3. 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.

4. A method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis as claimed in any one of claims 1 to 3, 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 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 quickly sintered to obtain a multi-layer catalytic electrode.

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

6. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 4, 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).

7. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 4, 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.

8. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 4, characterized in that: 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.

9. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 4, characterized in that: In S3, the rapid sintering conditions are: sintering temperature is 600-1000° C., and sintering time is 10-30 seconds.

10. The method for preparing a multilayer nickel mesh catalytic electrode for producing hydrogen by alkaline water electrolysis according to claim 4, 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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