Process for the preparation of carbon-supported platinum ternary alloy catalysts

Abstract

The application provides a preparation method of a carbon-supported platinum ternary alloy catalyst, and the catalyst takes carbon black as a carrier; first, Pt-Ni nanoparticles are uniformly dispersed on the surface of the carbon black carrier through microwave reduction; then, Cu is deposited on the surface of the Pt-Ni alloy phase to obtain the carbon-supported platinum ternary alloy catalyst, and the structural formula of the catalyst is Cu-Pt-Ni / C; wherein the mass percentage of platinum is 20%-50%, and the atomic ratio of the metal Pt, the metal Ni and the metal Cu is 2-6:1:2-6. The preparation method of the carbon-supported platinum ternary alloy catalyst can make the alloy phase after reduction more uniformly distributed on the surface of the carbon carrier through microwave reduction; and the catalyst forms a ternary alloy phase, which can improve the catalytic activity and stability of the catalyst under the premise of reducing the cost.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a method for preparing a carbon-supported platinum ternary alloy catalyst. Background Technology

[0002] Pt / C catalysts have attracted widespread attention due to their excellent ORR activity at low temperatures. However, the limited reserves and high price of platinum, as well as the need to improve the utilization efficiency and electrochemical stability of Pt / C catalysts, have seriously affected the commercialization of Pt / C catalysts in fuel cells. Summary of the Invention

[0003] The purpose of this invention is to overcome and supplement the shortcomings of existing technologies by providing a method for preparing a carbon-supported platinum ternary alloy catalyst. This method uses a Cu-Pt-Ni alloy catalyst to replace the traditional single platinum catalyst. The introduction of copper and nickel not only significantly reduces the cost of the catalyst, but also, through the formation of the Cu-Pt-Ni ternary alloy, achieves a synergistic catalytic effect, thereby enhancing catalytic activity. The technical solution adopted in this invention is as follows:

[0004] A method for preparing a carbon-supported platinum ternary alloy catalyst, wherein: the catalyst uses carbon black as a support, firstly, microwave-reduced Pt-Ni nanoparticles are uniformly dispersed on the surface of the carbon black support, and then Cu is deposited on the surface of the Pt-Ni alloy phase to obtain a carbon-supported platinum ternary alloy catalyst with the structural formula Cu-Pt-Ni / C; wherein the mass percentage of platinum is 20%-50%, and the atomic ratio of metallic Pt, metallic Ni and metallic Cu is 2-6:1:2-6.

[0005] Preferably, the preparation method of the carbon-supported platinum ternary alloy catalyst is as follows:

[0006] S1. Add carbon powder to a solvent at a mass ratio of 1:60 to 100, sonicate at 10 to 30°C for 1 to 5 hours, then shear for 1 to 2 hours and stir at room temperature to obtain a carbon carrier solution.

[0007] S2. Add the Pt and Ni precursor solutions to the reducing agent, stir thoroughly, then add the complexing agent and stabilizer and stir for 3-5 hours. Adjust the pH value to 9-12 with an alkaline solution to obtain a mixed solution. Add the mixed solution to the carbon support solution, introduce an inert gas, and stir at 60-90℃ for 1-2 hours to uniformly disperse the active material on the surface of the carbon support to obtain a slurry.

[0008] S3. Under inert gas protection, microwave heat the slurry to 120~180℃ and react for 3~10 minutes to fully reduce Pt and Ni;

[0009] S4. The solution after reduction in step S3 is filtered and washed until the conductivity of the filtrate is lower than 50 μs / m. The filter cake is vacuum dried at 60~100℃ for 2~24h. The obtained powder is reduced at 400~700℃ for 2~4h under hydrogen atmosphere to obtain Pt-Ni / C catalyst precursor.

[0010] S5. Dissolve 0.001~0.005 mol of Pt-Ni / C catalyst precursor in 30~80 ml of deionized water, add 1~10 ml of 3M triethanolamine and 1~10 ml of 14.4M ammonia, stir continuously for 3 h, and gradually add 1~10 ml of 1M thiourea, then add 0.2~3.0 ml of 0.005M cuprous chloride to control copper doping. Finally, transfer the above mixed solution to a hydrothermal reactor and react at 150~200℃ for 6~10 h to obtain Cu-Pt-Ni / C catalyst.

[0011] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the solvent in step S1 is a mixed solvent of ethylene glycol and ultrapure water, with a volume ratio of ethylene glycol to ultrapure water of 1:2~6.

[0012] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the platinum-containing solution in step S1 is one or both of chloroplatinic acid and chloroplatinate.

[0013] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the nickel-containing solution in step S1 is one or both of nickel acetylacetonate and nickel nitrate.

[0014] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the alkaline solution in step S2 is one or both of sodium hydroxide and sodium carbonate solutions.

[0015] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the reducing agent in step S2 is one or more of ethylene glycol, isopropanol, and ethanol.

[0016] Preferably, in the method for preparing the carbon-supported platinum ternary alloy catalyst, the complexing agent in step S2 is one or more of ethylenediamine, sodium citrate, and sodium chloride; and the stabilizer is one or more of sodium acetate, sodium carbonate, and sodium formate.

[0017] Advantages of this invention:

[0018] (1) The preparation method of the carbon-supported platinum ternary alloy catalyst of the present invention uses microwave reduction to make the alloy phase distributed more uniformly on the surface of the carbon support after reduction; the formation of the ternary alloy phase of the catalyst improves the catalytic activity and stability of the catalyst while reducing the cost.

[0019] (2) The preparation method of the carbon-supported platinum ternary alloy catalyst of the present invention introduces a Cu layer on the surface of the Pt-Ni alloy phase, which effectively reduces carbon loss and the migration and agglomeration of the Pt-Ni alloy phase. Moreover, the catalyst preparation process is simple and easy to industrialize. Attached Figure Description

[0020] Figure 1 This is an oxygen reduction polarization curve diagram of Embodiment 1 and the comparative example of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] Example 1

[0023] S1. Add 0.5g of carbon powder to 30ml of ethylene glycol solution, sonicate at room temperature for 60min, shear for 1h and stir continuously to obtain carbon support solution;

[0024] S2. Add 0.68g of chloroplatinic acid and 0.24g of nickel nitrate to 70ml of ethylene glycol solution and stir thoroughly. Add 4g of sodium citrate and stir continuously for 3 hours. Add 4g of sodium chloride and 0.56g of sodium carbonate and continue stirring at room temperature for 2 hours. Add an appropriate amount of 1mol / L sodium hydroxide solution to adjust the pH to 10. Add the mixed solution of Pt and Ni and the carbon support solution to the reactor, purge with argon gas, and stir at 80℃ for 1 hour to obtain the slurry.

[0025] S3. Under argon protection, microwave heat the slurry to 120°C for 5 minutes to allow Pt and Ni to be fully reduced;

[0026] S4. Filter the solution after the reaction, wash it several times with distilled water until the conductivity of the filtrate is less than 50 μS / m and no chloride ion residue is detected in the filtrate. Then dry it in a vacuum drying oven at 80℃ for 12h. The resulting powder is reduced at 600℃ under hydrogen conditions for 2h to obtain the Pt-Ni / C catalyst precursor.

[0027] S5. Dissolve 0.002 mol of Pt-Ni / C catalyst precursor in 50 ml of deionized water, gradually add 5 ml of 3M triethanolamine and 5 ml of 14.4M ammonia, stir continuously for 3 h, slowly add 4 ml of 1M thiourea by peristaltic pump, then add 0.5 ml of 0.005M cuprous chloride aqueous solution, and finally transfer the mixture to a hydrothermal reactor and react at 180 °C for 6 h to obtain Cu-Pt-Ni / C ternary alloy catalyst.

[0028] The obtained Cu-Pt-Ni / C ternary alloy catalyst nanoparticles have a particle size of ~4 nm and a metal dispersion of 34.8%.

[0029] Example 2

[0030] S1. Add 2g of carbon powder to 80ml of ethylene glycol solution, sonicate at room temperature for 1h, shear for 1.5h, and then stir continuously at room temperature to obtain a carbon support solution;

[0031] S2. Take 3.2g of chloroplatinic acid and 1.34g of nickel nitrate and add them to 220ml of ethylene glycol solution. Stir continuously for 3h. Add 16g of sodium citrate and 2.05g of sodium acetate and continue stirring at room temperature for 3h. Add an appropriate amount of 1mol / L sodium hydroxide solution to adjust the pH value to 12. Add the mixed solution of Pt and Ni and the carbon support solution to the reactor, purge with argon gas and stir at 80℃ for 1h to obtain the slurry.

[0032] S3. Under argon protection, microwave heat the slurry to 130°C for 4 minutes to allow Pt and Ni to be fully reduced;

[0033] S4. After the reaction, the solution is thoroughly filtered and washed until the conductivity of the filtrate is less than 50 μs / m. The filter cake is vacuum dried at 120°C for 12 h. The resulting powder is reduced at 700°C for 1 h under a hydrogen atmosphere to obtain a carbon-supported catalyst precursor with a Pt-Ni alloy phase.

[0034] S5. Dissolve 0.005 mol of Pt-Ni / C catalyst precursor in 100 ml of deionized water, add 10 ml of 3M triethanolamine and 10 ml of 14.4M ammonia, and stir continuously for 3 h. Gradually add 10 ml of 1M thiourea, then add 1.2 ml of 0.005M cuprous chloride solution. Finally, transfer the mixed solution to a hydrothermal reactor and react at 200℃ for 6 h to obtain Cu-Pt-Ni / C with good Cu coverage.

[0035] Example 3

[0036] S1. Add 1g of carbon powder to 80ml of ethylene glycol aqueous solution, with a volume ratio of ethylene glycol to ultrapure water of 1:3. Sonicate at room temperature for 1h, shear for 1h, and then stir continuously at room temperature to obtain a carbon support solution.

[0037] S2. Take 1.4g of chloroplatinic acid and 0.48g of nickel nitrate and add them to 120ml of ethylene glycol solution. Stir continuously for 3h. Add 6g of sodium citrate and 1.14g of sodium formate. Continue stirring at room temperature for 3h. Add an appropriate amount of 1mol / L sodium hydroxide solution to adjust the pH value to 12. Add the mixed solution of Pt and Ni and the carbon support solution to the reactor. Purge with argon gas and stir at 80℃ for 2h to obtain the slurry.

[0038] S3. Under argon protection, microwave heat the slurry to 120°C for 4 minutes to allow Pt and Ni to be fully reduced;

[0039] S4. After the reaction, the solution is thoroughly filtered and washed until the conductivity of the filtrate is lower than 50 μs / m. The filter cake is vacuum dried at 100°C for 12 h. The resulting powder is reduced at 700°C for 1 h under a hydrogen atmosphere to obtain a carbon-supported catalyst precursor with a Pt-Ni alloy phase.

[0040] S5. Dissolve 0.003 mol of Pt-Ni / C catalyst precursor in 80 ml of deionized water, add 6 ml of 3M triethanolamine and 6 ml of 14.4M ammonia, and stir continuously for 3 h. Gradually add 6 ml of 1M thiourea, then add 0.75 ml of 0.005M cuprous chloride solution. Finally, transfer the mixed solution to a hydrothermal reactor and react at 190℃ for 6 h to obtain Cu-Pt-Ni / C with good Cu coverage.

[0041] The obtained Cu-Pt-Ni / C ternary alloy catalyst nanoparticles have a particle size of approximately 5 nm and a metal dispersion of 32.4%.

[0042] The catalyst prepared in Example 1 was compared with a commercial JM Pt / C catalyst (comparative example) for half-cell ORR testing. The testing method was as follows: 1. Accurately weigh 5 mg ± 0.05 mg of catalyst; 2. Add 50 μL of ultrapure water, 1.8 ml of isopropanol, and 40 μL of 5% Nafion solution to the weighed catalyst in sequence; 3. The catalyst loading on the electrode surface was 100 μg / cm³. 2 1. Take an appropriate amount of evenly dispersed slurry and drop it three times onto the smooth and clean surface of the disc electrode, and let it air dry naturally to serve as the working electrode; 2. Place the electrode in the electrolytic cell to form a three-electrode system, with the electrolyte being a 0.1M HClO4 solution; 3. Rotate the disc electrode at 1600 rpm and scan forward at a scanning speed of 20 mV / s to test the linear voltammetric curve.

[0043] Test results are as follows Figure 1 As shown, the formation of the Cu-Pt-Ni ternary alloy effectively improves the electrochemical performance, and the catalyst prepared in Example 1 has significantly better performance than the commercial JM Pt / C catalyst.

[0044] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a carbon-supported platinum ternary alloy catalyst, characterized in that: The catalyst uses carbon black as a support. First, microwave-reduced Pt-Ni nanoparticles are uniformly dispersed on the surface of the carbon black support. Then, Cu is deposited on the surface of the Pt-Ni alloy phase to obtain a carbon-supported platinum ternary alloy catalyst with the structural formula Cu-Pt-Ni / C. The mass percentage of platinum is 20%-50%, and the atomic ratio of metallic Pt, metallic Ni and metallic Cu is 2-6:1:2-6. The specific preparation method is as follows: S1. Add carbon powder to a solvent at a mass ratio of 1:60 to 100, sonicate at 10 to 30°C for 1 to 5 hours, then shear for 1 to 2 hours and stir at room temperature to obtain a carbon carrier solution. S2. Add the Pt and Ni precursor solutions to the reducing agent, stir thoroughly, then add the complexing agent and stabilizer and stir for 3-5 hours. Adjust the pH value to 9-12 with an alkaline solution to obtain a mixed solution. Add the mixed solution to the carbon support solution, introduce an inert gas, and stir at 60-90℃ for 1-2 hours to uniformly disperse the active material on the surface of the carbon support to obtain a slurry. S3. Under inert gas protection, microwave heat the slurry to 120~180℃ and react for 3~10 minutes to fully reduce Pt and Ni; S4. The slurry after reduction in step S3 is filtered and washed until the conductivity of the filtrate is lower than 50 μs / m. The filter cake is vacuum dried at 60~100℃ for 2~24h. The powder obtained is reduced at 400~700℃ for 2~4h under hydrogen atmosphere to obtain Pt-Ni / C catalyst precursor. S5. Dissolve 0.001~0.005 mol of Pt-Ni / C catalyst precursor in 30~80 ml of deionized water, add 1~10 ml of 3M triethanolamine and 1~10 ml of 14.4M ammonia, stir continuously for 3 h, and gradually add 1~10 ml of 1M thiourea, then add 0.2~3.0 ml of 0.005M cuprous chloride to control copper doping and form a mixed solution. Finally, transfer the above mixed solution to a hydrothermal reactor and react at 150~200℃ for 6~10 h to obtain Cu-Pt-Ni / C catalyst.

2. The preparation method of the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: The solvent in step S1 is a mixture of ethylene glycol and ultrapure water, with a volume ratio of ethylene glycol to ultrapure water of 1:2~6.

3. The preparation method of the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: In step S2, the precursor solution of Pt is one or both of chloroplatinic acid and chloroplatinate.

4. The preparation method of the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: In step S2, the precursor solution of Ni is one or both of nickel acetylacetonate and nickel nitrate.

5. The method for preparing the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: In step S2, the alkaline solution is one or both of sodium hydroxide and sodium carbonate solutions.

6. The method for preparing the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: The reducing agent in step S2 is one or more of ethylene glycol, isopropanol, and ethanol.

7. The method for preparing the carbon-supported platinum ternary alloy catalyst as described in claim 1, characterized in that: In step S2, the complexing agent is one or more of ethylenediamine and sodium citrate; the stabilizer is one or more of sodium acetate, sodium carbonate, and sodium formate.

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