Durable catalyst for fuel cell and preparation method thereof
By compositeing polypyrrole and TiO2 and modifying the carrier with dopamine, the corrosion and deterioration of fuel cell catalyst support is solved, and a catalyst with high activity and high durability is achieved, extending the service life of the fuel cell and improving its performance.
Patent Information
- Application Number
- CN202411758232.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-03
- Publication Date
- 2025-03-25
AI Technical Summary
The existing fuel cell catalyst carrier fails during corrosion and deterioration, resulting in a decrease in the durability and effectiveness of the catalyst, affecting the long-lasting operation of the fuel cell.
The carrier precursor is obtained by compositeing polypyrrole (PPy) and TiO2, and surface modification is used to form a catalyst support with high activity and high durability, enhancing the interaction force between the support and the platinum catalyst.
It improves the durability and activity of the catalyst, enhances the binding force between the support and the platinum catalyst, extends the service life of the fuel cell, and improves its overall efficiency.
Abstract
Description
Technical Field
[0003] The invention belongs to the technical field of fuel cells, and in particular relates to a durable catalyst for fuel cells and a preparation method thereof. Background Art
[0005] Proton exchange membrane fuel cells (PEMFCs), as an efficient and environmentally friendly energy conversion device, have the core function of directly converting chemical energy into electrical energy. Among them, Pt / C catalysts occupy the core position of PEMFCs. Its key components are precious metals such as efficient catalytic elements Pt and supporting carriers. It can be seen that the performance of the catalyst directly affects the overall performance of PEMFC. Among them, if the catalyst carrier deteriorates significantly, such as suffering from severe corrosion, it will directly cause a series of negative effects. Corrosion not only erodes the supporting sites originally used to anchor platinum-based nanoparticles, but also weakens the binding force between the carrier and these active nanoparticles, thereby leading to the aggregation and even shedding of catalytic metal nanoparticles. This series of chain reactions significantly accelerates the failure process of the electrocatalyst and poses a serious threat to the long-term operation of PEMFC. Therefore, selecting and designing catalyst carrier materials with excellent corrosion resistance and efficient transmission characteristics, and improving the binding force between the carrier and Pt nanocatalyst particles, is one of the key strategies to improve the performance and life of PEMFC. Summary of the invention
[0007] In view of the above problems existing in the prior art, the present invention provides a durable catalyst for a fuel cell and a preparation method thereof, which can provide a fuel cell catalyst with high activity and high durability.
[0008] To achieve the above object, the technical solution provided by the present invention is as follows:
[0009] In a first aspect, the present application provides a method for preparing a durable catalyst for a fuel cell, comprising the following steps:
[0010] S1: Mix polypyrrole, Ti(NO3)4 and uric acid and dissolve them in water, react at 70-90°C for 3-4h, wash and dry them, and then put them into a tube furnace for carbonization under an oxygen atmosphere to obtain a carrier precursor;
[0011] S2: mixing dopamine with tris(hydroxymethylaminomethane) buffer to obtain a mixed solution; adding a carrier precursor to the mixed solution, polymerizing dopamine and drying to obtain a composite carrier;
[0012] S3: adding the composite carrier into a solution containing the platinum complex, adding a reducing agent for reduction, washing and drying to obtain the durable catalyst.
[0013] Optionally, the mass molar ratio of the polypyrrole to Ti(NO3)4 is (3-5): 1 g / mol.
[0014] Optionally, the carbonization condition in S1 is 300-500° C. for 3-5 h.
[0015] Optionally, the ratio of uric acid to water in S1 is 0.1-0.25 mol / L, and the ratio of Ti(NO3)4 to water is 0.4-0.6 mol / L.
[0016] Optionally, the mass ratio of the carrier precursor to dopamine in S2 is 1:(0.1-0.8).
[0017] Optionally, the dopamine polymerization reaction is carried out at room temperature for 18-24 hours.
[0018] Optionally, the reduction reaction condition is reflux at 60-120° C. for 15-48 h under nitrogen atmosphere.
[0019] Optionally, the concentration of the platinum complex in the platinum complex solution is 2-8%; the platinum complex is hexachloroplatinic acid, platinum nitrate or dichlorotetraamineplatinum, and the solvent in the platinum complex solution is water, ethanol or ammonia solution.
[0020] Optionally, the reducing agent is ascorbic acid, formic acid, sodium borohydride or potassium borohydride.
[0021] On the other hand, the present application also provides a method for preparing a durable catalyst for a fuel cell, which is obtained by the preparation method described in the first aspect.
[0022] Compared with the prior art, this application has at least the following beneficial effects:
[0023] The present invention obtains a carrier precursor by compounding polypyrrole (PPy) and TiO2; then uses an aqueous dopamine solution with excellent adhesion as an interface modifier to perform surface modification on the carrier precursor, thereby obtaining a fuel cell catalyst with high activity and high durability. The fuel cell catalyst obtained in the present application has a strong interaction force between the composite carrier and the platinum catalyst, thereby improving the durability of the catalyst. DETAILED DESCRIPTION
[0025] The present invention is described in further detail below:
[0026] The experimental methods used in the embodiments of the present invention are conventional methods unless otherwise specified.
[0027] The reagents and materials used in this example can all be purchased conventionally. The quantitative experiments involved in the examples were repeated at least three times, and the results were averaged.
[0028] Source of raw materials:
[0029] Polypyrrole: degree of polymerization is n=200-800.
[0030] Example 1
[0031] A method for preparing a catalyst for a proton exchange membrane fuel cell, comprising the following steps:
[0032] 200 mg of polypyrrole PPy, 0.05 mol Ti(NO3)4, and 0.02 mol uric acid were dissolved in 100 mL of deionized water and ultrasonicated for 30 min to fully dissolve. The dispersed solution was then placed in an oil bath pot and stirred continuously at 80°C for 4 h. After the obtained solution was filtered, rinsed and dried, the sample was placed in a tube furnace (air) at 350°C for 4 h to obtain a carrier precursor.
[0033] Weigh 2 g of dopamine (DA) and dissolve it in a Tris-HCl buffer solution with a concentration of 0.01 mol / L. Stir evenly to obtain a mixed solution. Weigh 10 g of the carrier precursor and immerse it in the mixed solution. React at 25°C for 24 h. After the reaction is completed, wash the composite carrier and dry it at 60°C for 24 h to obtain a composite carrier.
[0034] 4.01 g of hexachloroplatinic acid was dissolved in 150 g of pure water, stirred evenly, and then treated with 500 W, 50 KHz ultrasound in an ice water bath for 60 minutes to obtain a platinum complex solution.
[0035] 2.86 g of the composite carrier was evenly dispersed in 286 g of methanol. At 10 °C and 2500 rpm, the previously prepared platinum complex solution was added dropwise to the composite carrier methanol dispersion, and stirred for 240 min to mix evenly. Then, an ascorbic acid aqueous solution (28.65 g of ascorbic acid was dissolved in 250 mL of water) was added. After stirring for 60 min, it was refluxed at 60 °C for 24 h under nitrogen protection, filtered, washed, and dried to obtain a durable catalyst.
[0036] Embodiment 2:
[0037] A method for preparing a catalyst for a proton exchange membrane fuel cell, comprising the following steps:
[0038] 200 mg PPy, 0.05 mol Ti(NO3)4, and 0.02 mol uric acid were dissolved in 100 mL of deionized water and ultrasonicated for 30 min to fully dissolve. The dispersed solution was then placed in an oil bath at 80 ° C and stirred for 4 h. After the obtained solution was filtered, rinsed and dried, the sample was placed in a tube furnace (air) at 350 ° C for 4 h to obtain a carrier precursor.
[0039] Weigh 5g of DA and dissolve it in a 0.01mol / L Tris-HCl buffer solution, stir evenly to obtain a mixed solution, weigh 10g of the carrier precursor, immerse it in the mixed solution, and react at 25℃ for 24 hours. After the reaction, wash the composite carrier and dry it in a 60℃ oven for 24 hours to obtain a composite carrier.
[0040] 4.24 g of platinum nitrate was dissolved in 90.45 g of ethanol, stirred evenly, and then treated with 500 W, 50 KHz ultrasound in an ice water bath for 60 minutes to obtain a platinum complex solution.
[0041] 2.59 g of the composite carrier was evenly dispersed in 259 g of methanol. At 10 °C and 2500 rpm, the previously prepared platinum complex solution was added dropwise to the composite carrier methanol dispersion, and stirred for 240 min to mix evenly. Then, an aqueous formic acid solution (38.85 g of formic acid was dissolved in 500 mL of water) was added, and after stirring for 60 min, it was refluxed at 80 °C for 48 h under nitrogen protection, filtered, washed, and dried to obtain a durable catalyst.
[0042] Embodiment 3:
[0043] This embodiment provides a catalyst for a proton exchange membrane fuel cell, including a composite carrier and metal platinum supported on the composite carrier.
[0044] 200 mg PPy, 0.05 mol Ti(NO3)4, and 0.02 mol uric acid were dissolved in 100 mL of deionized water and ultrasonicated for 30 min to fully dissolve. The dispersed solution was then placed in an oil bath at 80 ° C and stirred for 4 h. After the obtained solution was filtered, rinsed and dried, the sample was placed in a tube furnace (air) at 350 ° C for 4 h to obtain a carrier precursor.
[0045] Weigh 7g of DA and dissolve it in a 0.01mol / L Tris-HCl buffer solution, stir evenly to obtain a mixed solution, weigh 10g of the carrier precursor, immerse it in the mixed solution, and react for 24 hours at 25°C. After the reaction, wash the composite carrier and dry it in a 60°C oven for 24 hours to obtain a composite carrier.
[0046] 6.78 g of hexachloroplatinic acid was dissolved in 135.65 g of 30% by mass ethanol aqueous solution, stirred evenly, and then treated with 500 W, 50 KHz ultrasound in an ice water bath for 60 minutes to obtain a platinum complex solution.
[0047] 1.7 g of the composite carrier was evenly dispersed in 170 g of methanol. At 10 °C and 2500 rpm, the previously prepared platinum complex solution was added dropwise to the composite carrier dispersion, stirred for 240 min to mix evenly, and then a sodium borohydride aqueous solution (46.8 g of sodium borohydride was dissolved in 500 mL of water) was added and stirred for 120 min. Then, under a nitrogen protection environment, the mixture was refluxed at 100 °C for 48 h, filtered, washed, and dried to obtain a durable catalyst.
[0048] Comparative Example 1:
[0049] This comparative example is compared with Example 1, in which the difference is that a carbon black carrier is used and dopamine modification is not performed. The specific steps are as follows:
[0050] 4.01 g of hexachloroplatinic acid was dissolved in 150 g of pure water, stirred evenly, and then treated with 500 W, 50 KHz ultrasound in an ice water bath for 60 minutes to obtain a platinum complex solution.
[0051] 2.86 g of carbon black was evenly dispersed in 286 g of methanol. At 10°C and 2500 rpm, the previously prepared platinum complex solution was added dropwise to the carbon black dispersion and stirred for 240 min to obtain a mixed solution. 28.65 g of ascorbic acid was dissolved in 250 mL of water and then added to the mixed solution and mixed. The mixture was stirred for 60 min and then refluxed at 60°C for 24 h under nitrogen protection, filtered, washed and dried to obtain a catalyst Pt / C.
[0052] Comparative Example 2
[0053] The difference between this comparative example and Example 1 is that no polypyrrole is added.
[0054] Comparative Example 3
[0055] The difference between this comparative example and Example 1 is that 200 mg of polypyrrole PPy is mixed with 0.5 mol of TiO2 with a particle size of 100-150 nm, and ultrasonicated for 30 minutes to fully dissolve it. Then the dispersed solution is placed in an oil bath pot at 80°C and stirred for 4 hours. After the obtained solution is filtered, rinsed and dried, the sample is placed in a tube furnace (air) at 350°C for 4 hours to obtain a carrier precursor.
[0056] The performance of the catalysts obtained in Examples 1-3 and Comparative Examples 1-3 was tested by performing square wave cycles at a voltage of 0.6 V (3 s) for 30k cycles. The specific results are shown in the table below.
[0057] Table 1 Performance comparison of catalysts before and after square wave circulation
[0058] catalyst <![CDATA[Initial ECSA (m 2 / gpt)]]> <![CDATA[Cycling 30K times of ECSA (m 2 / gpt)]]> Initial MA (mA / mgpt) 30K cycles MA (mA / mgpt) Comparative Example 1 45.66 35.78 152.14 110.76 Comparative Example 2 22.54 13.21 100.76 64.32 Comparative Example 3 50.22 40.16 178.87 127.75 Example 1 66.54 61.29 234.51 220.11 Example 2 68.32 62.82 250.22 231.32 Example 3 65.78 60.44 277.43 254.23
[0059] According to Table 1, the catalyst for proton exchange membrane fuel cell prepared by the method of the present invention has a mass specific activity of more than 200 mA / mg and an electrochemical active area of 60 m 2 / g or more, which is significantly higher than the comparative example. In addition, the stability of the catalyst prepared by the method of the present invention is significantly higher than that of the comparative example after 30k cycles, and the attenuation rate of the electrochemical active area of the platinum-carbon catalyst after 30k cycles is within 10%, which is higher than the existing technology. This shows that the platinum-carbon catalyst prepared by the present invention has good catalytic activity and durability, and can be used in proton exchange membrane fuel cells.
Claims
1. A method for preparing a durable catalyst for a fuel cell, characterized in that: The steps include: S1: Mix polypyrrole, Ti(NO3)4 and uric acid and dissolve them in water, react at 70-90°C for 3-4h, wash and dry them, and then put them into a tube furnace for carbonization under an oxygen atmosphere to obtain a carrier precursor; S2: mixing dopamine with tris(hydroxymethylaminomethane) buffer to obtain a mixed solution; adding a carrier precursor to the mixed solution, polymerizing dopamine and drying to obtain a composite carrier; S3: mixing the composite carrier with the platinum complex solution, adding a reducing agent for reduction, washing and drying to obtain the durable catalyst.
2. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The mass molar ratio of the polypyrrole to Ti(NO3)4 is (3-5): 1 g / mol.
3. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The carbonization conditions described in S1 are 300-500° C. for 3-5 h.
4. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The ratio of uric acid to water in S1 is 0.1-0.25 mol / L, and the ratio of Ti(NO3)4 to water is 0.4-0.6 mol / L.
5. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The mass ratio of carrier precursor to dopamine in S2 is 1:(0.1-0.8).
6. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The dopamine polymerization reaction is carried out at room temperature for 18-24 hours.
7. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The reduction reaction condition is to reflux at 60-120° C. for 15-48 h under a nitrogen atmosphere.
8. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The concentration of platinum complex in the platinum complex solution is 2-8%; the platinum complex is hexachloroplatinic acid, platinum nitrate or dichlorotetraamineplatinum, and the solvent in the platinum complex solution is water, ethanol or ammonia solution.
9. The method for preparing a durable catalyst for a fuel cell according to claim 1, characterized in that: The reducing agent is ascorbic acid, formic acid, sodium borohydride or potassium borohydride.
10. A method for preparing a durable catalyst for a fuel cell, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 9.