Method for growing porous catalyst on gas diffusion layer
Through electroplating technology, a porous catalyst layer is formed on the gas diffusion layer produced by PEM water electrolysis, which solves the problems of high cost of noble metal oxide catalysts and difficult control of the catalyst layer structure, and achieves efficient, stable and low-cost catalyst layer preparation.
Patent Information
- Application Number
- CN202411591851.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-02-18
AI Technical Summary
In the existing PEM water electrolysis hydrogen production technology, noble metal oxide catalysts are costly, and commonly used coating methods have problems such as uneven thickness of the catalyst layer, poor adhesion, and difficult to control the pore structure, which affects the electrolytic performance and stability.
Electroplating technology is used to deposit a catalyst layer on the metal gas diffusion layer. By adding pore-forming agent to the electroplating solution, tiny insoluble particles or bubbles are formed, resulting in uneven deposition of catalyst ions and forming a porous catalyst layer.
The thickness uniformity of the catalyst layer and the formation of porous structure are achieved, the catalytic efficiency of electrolyzed water is improved, the long-term stability of the catalyst is ensured, and the production cost is reduced.
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Figure CN119465236A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a porous catalyst for proton exchange membrane (PEM) water electrolysis to produce hydrogen, and in particular to a method for growing the porous catalyst on a gas diffusion layer. Background Art
[0002] Proton exchange membrane (PEM) water electrolysis hydrogen production technology has become a research hotspot in hydrogen production technology due to its high efficiency and environmental protection. The performance and life of PEM electrolyzers depend to a large extent on the performance of anode catalysts. Currently, the commonly used anode catalysts are mainly precious metal oxides, such as ruthenium oxide (RuO2) and iridium oxide (IrO2). However, these precious metal catalysts are expensive, which restricts the widespread application of PEM water electrolysis hydrogen production technology. Developing catalysts with high catalytic activity, good durability and low cost is an important direction of current research.
[0003] The commonly used methods for coating the catalyst layer on the PEM gas diffusion layer include physical vapor deposition (PVD) and spraying technology. The slurry spraying technology is to spray the catalyst slurry on the membrane electrode or titanium substrate, and prepare the gas diffusion layer through drying and heat treatment steps. Its advantages are simple process and low cost, but there are also problems such as uneven thickness of the catalyst layer, poor adhesion, and difficult to control pore structure, which affect the electrolysis performance and stability. PVD is a technology that deposits metals on a substrate to form a thin film by evaporation or sputtering under vacuum conditions. PVD technology can prepare a catalyst layer with high purity, high density and good uniformity, but it also has the following shortcomings: the equipment is complex and expensive, the PVD equipment is complex, and the initial investment and maintenance costs are high; the deposition rate is low, which is suitable for preparing thin films rather than thick layer structures; the environmental requirements are high, and it needs to be carried out in a high vacuum environment, and the operation and process control are complex. Summary of the invention
[0004] In view of the deficiencies of the prior art, the present invention aims to provide a method for growing a porous catalyst on a gas diffusion layer.
[0005] In order to achieve the above object, the present invention adopts the following technical solution:
[0006] A method for growing a porous catalyst on a gas diffusion layer comprises the following steps:
[0007] S1. Pretreatment of the metal gas diffusion layer: cleaning the surface of the metal gas diffusion layer in an acid solution to remove impurities and an oxide layer on the surface;
[0008] S2. Preparation of electroplating solution: preparing an electroplating solution containing catalyst ions and a pore-forming agent;
[0009] S3, electroplating process: using the electroplating solution prepared in step S2 to perform an electroplating reaction on the metal gas diffusion layer treated in step S1, during the electroplating process, the pore-forming agent forms tiny insoluble particles, colloids or bubbles in the electroplating solution, and these insoluble particles, colloids or bubbles adhere to the surface of the metal gas diffusion layer during the electroplating process, hindering the deposition of some catalyst ions or causing local potential changes, resulting in uneven deposition of catalyst ions and forming holes, thereby forming a porous catalyst layer;
[0010] S4, post-treatment: cleaning and heat treating the metal gas diffusion layer after the porous catalyst layer is grown.
[0011] Furthermore, in step S1, the metal gas diffusion layer is one or more of titanium fiber sintered felt, titanium powder sintered felt, and titanium mesh.
[0012] Further, in step S2, the catalyst ions include one or more of Pt, Ir, Ta, Mo, Ru, Au, Cr, Sn, W, Si and C elements, and the concentration of the catalyst ions in the electroplating solution is 0.05-5 mol / L; the pore-forming agent includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, methyl cellulose, carboxymethyl cellulose, ammonium bicarbonate, sodium carbonate, sodium chloride, starch and its derivatives, azobisisobutyronitrile, sodium aminosulfonate, polystyrene microspheres, silica microspheres, lignin, cellulose, and gelatin, and the concentration of the pore-forming agent in the electroplating solution is 0.1-5 g / L.
[0013] Furthermore, the specific process of step S1 is as follows:
[0014] Pretreatment of the metal gas diffusion layer: Place the metal gas diffusion layer in a nitric acid solution with a mass concentration of 10% for ultrasonic cleaning for 10-30 minutes; then repeatedly rinse the metal gas diffusion layer with deionized water until the pH value of the washing water is close to neutral; then place the metal gas diffusion layer in an oven and dry it at 50-80°C for 2 hours.
[0015] Further, in step S3, the three-electrode system or the two-electrode system is placed in an electroplating tank, ensuring that all electrodes are completely immersed in the electroplating solution;
[0016] When a three-electrode system is used, the metal gas diffusion layer is used as the working electrode, a platinum sheet or a platinum mesh is used as the counter electrode, and a saturated calomel electrode, silver chloride or a standard hydrogen electrode is used as the reference electrode; when a two-electrode system is used, the metal gas diffusion layer is used as the working electrode, and a platinum sheet or a platinum mesh is used as the counter electrode.
[0017] Furthermore, the electroplating mode adopts one or more of a constant current mode, a constant voltage mode and a pulse potential mode;
[0018] When the constant current mode or constant voltage mode is used, the constant voltage is 0.1-5V or the constant current density is 1-20mA / cm 2 , the electroplating time is 10-60 minutes, the electroplating solution temperature is 10-90°C, and uniform stirring is maintained during the electroplating process;
[0019] When the pulse plating mode is used, high current density and low current density pulse current are applied alternately during the plating process; a high current density of 5-20mA / cm is applied in the high current density stage. 2 The duration is 0.1-10 seconds. The low current density stage applies a low current density of 0-5mA / cm 2 Last for 2-30 seconds; alternately apply pulse currents of high current density and low current density until the total electroplating time reaches 5-60 minutes; the temperature of the electroplating solution is 10-90°C.
[0020] It should be noted that in constant current mode or constant voltage mode, the electroplating solution is mainly controlled by natural diffusion, ion diffusion and bubble removal are slow, the structure of the deposited layer is relatively loose, and the connectivity of the porous structure is poor. In pulse deposition mode, since pulse deposition can deposit metal in a short time at high current density, and promote ion diffusion and bubble removal at low current density or rest stage, the pores have better connectivity, and the distribution and size of the pores are more controllable. By adjusting the pulse frequency, duty cycle and peak current, the size and density of the holes can be effectively adjusted.
[0021] Furthermore, in step S4, the cleaning process is as follows: after the electroplating is completed, the electroplated metal gas diffusion layer is repeatedly rinsed with deionized water to remove the electroplating solution remaining on the surface, and then the rinsed metal gas diffusion layer is dried at 60-80° C. for 1-2 hours.
[0022] Furthermore, in step S4, the specific process of the heat treatment is: low temperature oxidation treatment at 200-400° C. for 0.5-2 hours in an oxidizing gas atmosphere.
[0023] The invention also provides a gas diffusion layer with a porous catalyst layer produced by the method.
[0024] The beneficial effects of the present invention are:
[0025] 1. The method of the present invention can deposit a catalyst layer with uniform thickness on the metal gas diffusion layer through electroplating technology, thereby avoiding the problem of uneven thickness that may occur during the spraying process.
[0026] 2. The porous catalyst layer formed by the present invention is firmly bonded to the gas diffusion layer substrate and is not easy to fall off after proper heat treatment, thus ensuring the long-term stability of the catalyst.
[0027] 3. The present invention combines electroplating technology with the use of pore-forming agents to form a uniform porous structure during the electroplating process, which is beneficial to improving the catalytic efficiency of water electrolysis.
[0028] 4. The present invention uses low-temperature oxidation treatment on the gas diffusion layer after electroplating, which will not destroy the porous structure of the catalyst layer, and at the same time can convert the catalyst ions into corresponding oxides to ensure the high activity of the catalyst.
[0029] 5. Compared with the high cost of PVD equipment, the electroplating equipment of the present invention is relatively simple, low cost, and suitable for large-scale production applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 This is a schematic structural diagram of the gas diffusion layer prepared in Example 2 of the present invention. DETAILED DESCRIPTION
[0031] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.
[0032] Example 1
[0033] This embodiment provides a method for growing a porous catalyst on a gas diffusion layer, and the specific process is as follows:
[0034] Pretreatment of the metal gas diffusion layer: the titanium fiber sintered felt was placed in a nitric acid solution with a mass concentration of 10% for ultrasonic cleaning for 10 minutes; the titanium fiber sintered felt was then repeatedly rinsed with deionized water until the pH value of the washing water was close to neutral; thereafter, the titanium fiber sintered felt was placed in an oven and dried at 50°C for 2 hours.
[0035] Prepare electroplating solution: Mix 100g of ruthenium trichloride and 200ml of 37% concentrated hydrochloric acid solution, add water to adjust to c(H + )=2.0mol / L, the solid-liquid ratio of catalyst ion ruthenium and concentrated hydrochloric acid solution is 1g:24mL, then the mixed solution is heated to 70℃ until ruthenium trichloride is completely dissolved, and the ruthenium concentration is 41g / L. Then 10mL of 20% nitric acid solution is added dropwise, the ORP value reaches 950mV, and the reaction is carried out at a constant temperature for 30 minutes to obtain solution A. 36g of ammonium chloride is added to solution A, crystallized, filtered, and washed to obtain ammonium hexachlororuthenate, with a direct yield of 97%. Ammonium hexachlororuthenate can improve the solubility and stability of iridium ions, maintain high activity, and avoid premature precipitation.
[0036] Add 8.2g of chelating agent aminosulfonic acid and water to ammonium hexachlororuthenate to form a slurry, heat to 80°C, introduce protective gas SO2 to prevent the oxidation and decomposition of ammonium hexachlororuthenate, and dissolve the ammonium hexachlororuthenate to obtain solution B. Add 10mL of 2% sulfuric acid solution to solution B, heat to 60°C, and perform vacuum distillation to obtain a ruthenium plating solution. The vacuum pressure of the vacuum distillation is -0.06Mpa and the temperature is 70°C. The mass concentration of ruthenium ions in the ruthenium plating solution is 30g / L, and the molar concentration is 0.29mol / L. Then, 0.5g / L of pore-forming agent polyvinyl pyrrolidone is added to obtain an electroplating solution.
[0037] Electroplating process: Use an acid and alkali corrosion resistant electroplating tank, pre-treated titanium fiber sintered felt as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode. During the electroplating process, high current density (20mA / cm 2 , lasting 10 seconds) and low current density (5 mA / cm 2 , lasting 30 seconds), until the total plating time reaches 60 minutes and the plating solution temperature is 40°C.
[0038] Post-treatment: After the electroplating is completed, the electroplated titanium fiber sintered felt is repeatedly rinsed with deionized water to remove the electroplating solution and pore-forming agent remaining on the surface; the rinsed titanium fiber sintered felt is placed in an oven at 80°C and dried for 2 hours. Then it is taken out and subjected to low-temperature oxidation treatment at 400°C in a tube furnace for 2 hours in oxygen to convert ruthenium oxide.
[0039] Example 2
[0040] This embodiment provides a method for growing a porous catalyst on a gas diffusion layer, and the specific process is as follows:
[0041] Pretreatment of the metal gas diffusion layer: The titanium mesh was placed in a nitric acid solution with a mass concentration of 10% for ultrasonic cleaning for 30 minutes; the titanium mesh was then repeatedly rinsed with deionized water until the pH value of the washing water was close to neutral; the titanium mesh was then placed in an oven and dried at 80°C for 2 hours.
[0042] Prepare electroplating solution: Mix 50g iridium trichloride and 180ml 36% concentrated hydrochloric acid solution, transfer to the reactor, add water to adjust the solution to c(H + )=4mol / L, the solid-liquid ratio of the catalyst metal ion and the concentrated hydrochloric acid solution is 1g:21mL. The solution is heated to 75°C, and after the iridium trichloride is completely dissolved, a nitric acid solution with a mass concentration of 30% is slowly added dropwise until the ORP potential value in the solution reaches above 950mV, and then cooled to room temperature to obtain solution A. Ammonium chloride is added to solution A, and the mixture is crystallized, filtered, washed, and dried to obtain ammonium hexachloroiridate.
[0043] The ammonium hexachloroiridate was cleaned 5 times with a 16% ammonium chloride solution, and the water was drained with a vacuum pump. Then, the ammonium hexachloroiridate and the complexing agent aminosulfonic acid were mixed, and the mass ratio of iridium ion to aminosulfonic acid was 1:1. Water was added to form a slurry, stirred and mixed, and heated to 85°C.
[0044] Pass protective gas SO2 until ammonium hexachloroiridate is completely dissolved to obtain solution B. Add 10mL of 2% sulfuric acid solution to solution B and perform vacuum distillation to obtain iridium plating solution. The vacuum pressure of vacuum distillation is -0.06Mpa and the temperature is 70°C. Then add 1g / L of pore-forming agent ammonium bicarbonate to the iridium plating solution.
[0045] Electroplating process: Use an acid and alkali corrosion resistant electroplating tank, pretreated titanium mesh as the working electrode, platinum mesh as the counter electrode, and standard hydrogen electrode as the reference electrode. Apply a constant current of 10mA / cm during the electroplating process. 2 , until the total plating time reaches 60 minutes and the plating solution temperature is 20°C.
[0046] Post-treatment: After the electroplating is completed, the electroplated titanium mesh is repeatedly rinsed with deionized water to remove the electroplating solution and pore-forming agent remaining on the surface; the rinsed titanium mesh is placed in a vacuum oven for drying at 60°C for 1 hour. Then it is taken out and subjected to low-temperature oxidation treatment at 200°C in a muffle furnace for 1 hour in an air atmosphere to convert iridium oxide.
[0047] Figure 1 Schematic diagram of the structure of the titanium mesh porous iridium dioxide electrode prepared in this embodiment; 1 is the titanium mesh substrate, 2 is the electroplated iridium layer, 3 is the iridium oxide layer after heat treatment, and 4 is the pore structure.
[0048] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.
Claims
1. A method for growing a porous catalyst in a gas diffusion layer, characterized in that: The following steps are involved: S1. Pretreatment of the metal gas diffusion layer: cleaning the surface of the metal gas diffusion layer in an acid solution to remove impurities and an oxide layer on the surface; S2. Preparation of electroplating solution: preparing an electroplating solution containing catalyst ions and a pore-forming agent; S3, electroplating process: using the electroplating solution prepared in step S2 to perform an electroplating reaction on the metal gas diffusion layer treated in step S1, during the electroplating process, the pore-forming agent forms tiny insoluble particles, colloids or bubbles in the electroplating solution, and these insoluble particles, colloids or bubbles adhere to the surface of the metal gas diffusion layer during the electroplating process, hindering the deposition of some catalyst ions or causing local potential changes, resulting in uneven deposition of catalyst ions and forming holes, thereby forming a porous catalyst layer; S4, post-treatment: cleaning and heat treating the metal gas diffusion layer after the porous catalyst layer is grown.
2. The method according to claim 1, characterized in that In step S1, the metal gas diffusion layer is one or more of titanium fiber sintered felt, titanium powder sintered felt, and titanium mesh.
3. The method according to claim 1, characterized in that In step S2, the catalyst ions include one or more of Pt, Ir, Ta, Mo, Ru, Au, Cr, Sn, W, Si and C elements, and the concentration of the catalyst ions in the electroplating solution is 0.05-5 mol / L; the pore-forming agent includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, methyl cellulose, carboxymethyl cellulose, ammonium bicarbonate, sodium carbonate, sodium chloride, starch and its derivatives, azobisisobutyronitrile, sodium aminosulfonate, polystyrene microspheres, silica microspheres, lignin, cellulose, and gelatin, and the concentration of the pore-forming agent in the electroplating solution is 0.1-5 g / L.
4. The method according to claim 1, characterized in that: The specific process of step S1 is as follows: Pretreatment of the metal gas diffusion layer: Place the metal gas diffusion layer in a nitric acid solution with a mass concentration of 10% for ultrasonic cleaning for 10-30 minutes; then repeatedly rinse the metal gas diffusion layer with deionized water until the pH value of the washing water is close to neutral; then place the metal gas diffusion layer in an oven and dry it at 50-80°C for 2 hours.
5. The method according to claim 1, characterized in that In step S3, the three-electrode system or the two-electrode system is placed in an electroplating tank, ensuring that all electrodes are completely immersed in the electroplating solution; When a three-electrode system is used, the metal gas diffusion layer is used as the working electrode, a platinum sheet or a platinum mesh is used as the counter electrode, and a saturated calomel electrode, silver chloride or a standard hydrogen electrode is used as the reference electrode; when a two-electrode system is used, the metal gas diffusion layer is used as the working electrode, and a platinum sheet or a platinum mesh is used as the counter electrode.
6. The method according to claim 1 or 5, characterized in that: The electroplating mode adopts one or more of a constant current mode, a constant voltage mode and a pulse potential mode; When the constant current mode or constant voltage mode is used, the constant voltage is 0.1-5V or the constant current density is 1-20mA / cm 2 , the electroplating time is 10-60 minutes, the electroplating solution temperature is 10-90°C, and uniform stirring is maintained during the electroplating process; When the pulse plating mode is used, high current density and low current density pulse current are applied alternately during the plating process; a high current density of 5-20mA / cm is applied in the high current density stage. 2 The duration is 0.1-10 seconds. The low current density stage applies a low current density of 0-5mA / cm 2 Last for 2-30 seconds; alternately apply pulse currents of high current density and low current density until the total electroplating time reaches 5-60 minutes; the temperature of the electroplating solution is 10-90°C.
7. The method according to claim 1, characterized in that In step S4, the cleaning process is as follows: after the electroplating is completed, the electroplated metal gas diffusion layer is repeatedly rinsed with deionized water to remove the electroplating solution remaining on the surface, and then the rinsed metal gas diffusion layer is dried at 60-80° C. for 1-2 hours.
8. The method according to claim 1, characterized in that: In step S4, the specific process of the heat treatment is: low-temperature oxidation treatment at 200-400° C. for 0.5-2 hours in an oxidizing gas atmosphere.
9. A gas diffusion layer having a porous catalyst layer grown thereon, prepared by the method according to any one of claims 1 to 8.