Preparation method of carbon-supported platinum-copper alloy catalyst for proton exchange membrane fuel cells

Abstract

A method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell belongs to the field of fuel cells. The method involves fully impregnating a carbon support in a copper-containing solution, adding sodium hydroxide to adjust the solution pH, aging the solution, and then adding a reducing agent for full reduction to obtain carbon-supported cuprous oxide particles. The carbon-supported cuprous oxide particles are then fully impregnated in a platinum solution and the solution pH is adjusted, then transferred to a reactor, heated to 80-110°C, and hydrogen is introduced for pressurized hydrogen reduction to obtain a carbon-supported platinum-copper alloy catalyst. The carbon-supported platinum-copper alloy catalyst synthesized in two steps in an aqueous system has a mass activity greater than 0.6 A·mgPt ‑1 , which is superior to the quality activity of the mainstream platinum-carbon catalysts on the current market.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell. Background Art

[0002] The use of traditional fossil fuels results in significant CO2 emissions. The greenhouse effect caused by these CO2 emissions has led to a series of problems, including global warming, melting polar glaciers, and rising sea levels. Hydrogen, as a renewable energy source, produces environmentally friendly water as a reaction product and boasts a high mass energy density of 33,600 watt-hours per kilogram (W·h / kg), offering enormous potential to replace traditional fossil fuels. Fuel cells are devices that directly convert the chemical energy of a fuel and an oxidant into electricity through electrode reactions. Because they are not constrained by the Carnot cycle, they achieve energy conversion efficiencies of approximately 60% to 80%, two to three times higher than those of conventional internal combustion engines. They also offer low noise levels and minimal environmental impact, holding significant potential for applications in transportation, power generation, and energy storage. Furthermore, because the HOR reaction in fuel cells is much faster than the ORR reaction, and the voltage in the low current density region is largely determined by the catalytic activity of the oxygen reduction reaction (ORR) at the cathode, the ORR performance of the cathode catalyst has a crucial influence on fuel cell performance.

[0003] At present, the commonly used catalyst is platinum-carbon catalyst. Compared with other metal elements, platinum has the best catalytic performance. However, based on the relationship between metal ORR activity and O binding energy, the catalytic performance of platinum still has room for improvement. Around the 1980s, researchers found that when platinum forms an alloy with transition metals, it can not only reduce the amount of platinum, but also improve the ORR performance of the catalyst. The methods commonly used to prepare platinum-based alloy catalysts are: electrochemical method, template method, and solvent thermal method. The electrochemical method of preparing nanocrystals is to apply an external current to the catalyst precursor salt to deposit the catalyst ions at the cathode. This method is simple, convenient, fast, has a large output, and has good reproducibility, but requires electrochemical equipment and corresponding conditions (Lv Xiaomeng, Zhao Mengyuan, Hua Shaochun, et al. Preparation of dual precious metal catalysts by pulse electrodeposition and research on their electrochemical performance [J]. Surface Technology, 2024, 53(06): 206-213.). The template method is an effective method for preparing nanomaterials with different morphologies. Some nanomaterials with special morphologies, such as nanowires, nanobelts, and nanotubes, can be synthesized using the template method. However, there are also problems such as difficult template removal and complex process flows (Guo Yueling. Preparation and performance study of Pt3Cu catalyst supported on polypyrrole-modified carbon support [D]. Beijing University of Chemical Technology, 2023.). The solvothermal method involves simultaneously reducing and combining the precursor salts of two or more materials in an organic solvent to form a nanocatalyst material. This method has a simple process flow, the particle size and morphology of the product are easy to control, the product has good dispersibility, and the catalyst has high ORR activity. However, the production cost is high, making it inconvenient for industrial production (Lu BA, Sheng T., Tian N., etc. Octahedral PtCu alloy nanocrystals with high performance for oxygen reduction reaction and their enhanced stability by trace Au [J]. Nano Energy, 2017, 33: 65-71.). Summary of the Invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing a carbon-supported platinum-copper alloy catalyst for proton exchange membrane fuel cells with excellent electrochemical performance.

[0005] The preparation method of carbon-supported platinum-copper alloy catalyst for proton exchange membrane fuel cells has the following specific process:

[0006] A. Preparation of Carbon-Supported Cuprous Oxide

[0007] The copper salt is completely dissolved in pure water, and the copper concentration in the solution is controlled to be 0.35-2 g / L. A carbon support is then added to the solution, and the mass ratio of the carbon support to the copper is controlled to be 2-4.5:1. After stirring and impregnating for 4-6 hours, ultrasonic stirring is continued for 30-120 minutes to obtain a copper-containing precursor mixed solution.

[0008] A sodium hydroxide solution with a concentration of 5 to 20 g / L was added dropwise to a mixed solution containing a copper precursor, and the pH of the mixed solution was adjusted to 10 to 13. After aging for 20 to 60 minutes, a reducing agent was added according to a mass ratio of reducing agent to copper in the mixed solution of 0.4 to 2.5:1. The temperature was raised to 70 to 90°C, and the mixture was reacted for 15 to 60 minutes. The mixture was filtered and dried to obtain carbon-supported cuprous oxide particles. B. Preparation of carbon-supported platinum-copper alloy catalyst

[0009] A platinum solution with a platinum concentration of 0.50 to 1.5 g / L is prepared, and a sodium hydroxide solution with a concentration of 20 to 40 g / L is used to adjust the pH of the platinum solution to 1.5 to 5.0. Then, carbon-supported cuprous oxide particles are added to the platinum solution to obtain a platinum-containing mixed solution, wherein the molar ratio of Cu to Pt in the platinum-containing mixed solution needs to be controlled to be 1 to 3:1, and the solution is stirred and impregnated for 4 to 10 hours and ultrasonicated for 30 to 120 minutes. After the ultrasonication is completed, the pH of the platinum-containing mixed solution is adjusted to 5.5 to 8.0 using a sodium hydroxide solution with a concentration of 20 to 40 g / L, and the adjusted solution is then added to the solution. The platinum-containing mixed liquid is placed in a reactor, argon is introduced into the reactor, and after the oxygen in the reactor is completely driven out, the temperature is raised to 80-110° C., hydrogen is started to be introduced into the reactor, and the hydrogen partial pressure in the reactor is controlled to be 0.5-1 MPa. The solution is stirred at a rate of 200-350 rpm for 90-120 minutes, and then heating and stirring are stopped. When the temperature in the reactor drops below 50° C., the introduction of hydrogen is stopped and argon is introduced into the reactor to replace the hydrogen. When the hydrogen is completely replaced, the solid-liquid separation is carried out, the reaction mixture is washed with alcohol, and the reaction mixture is dried to obtain a carbon-supported platinum-copper alloy catalyst.

[0010] The platinum salt is platinum nitrate; the copper salt is at least one of copper nitrate trihydrate, copper chloride dihydrate, and copper sulfate pentahydrate; the carbon carrier is at least one of ECP600JD, EC600JD, and XC-72; the reducing agent is at least one of ascorbic acid and glucose; the sodium hydroxide, ascorbic acid, and glucose are analytical grade reagents. The hydrogen purity is not less than 99.99%; and the argon purity is not less than 99.99%.

[0011] Compared with the prior art, the present invention has the following beneficial effects: the carbon-supported platinum-copper alloy catalyst prepared by the present invention has a higher platinum utilization rate than the popular platinum-carbon catalyst on the market, and can replace part of the platinum in the popular platinum-carbon catalyst on the market, thereby reducing the catalyst preparation cost; the present invention uses cuprous oxide as a sacrificial template, and the prepared platinum-copper nanoalloy has good dispersibility. By controlling the morphology of the cuprous oxide template, the exposure of the highly catalytically active crystal face of the platinum-copper alloy can be achieved, and the electrochemical performance is significantly better than the popular platinum-carbon catalyst on the market, and its mass activity can reach 0.6A·mgPt -1 and above, which is more than 2.7 times that of the popular platinum-carbon catalyst currently on the market; by loading platinum on carbon-supported cuprous oxide particles, platinum coating on copper can be achieved, increasing the stability and durability of the catalyst; the reduction process of the present invention does not introduce impurity elements, avoiding the shielding of the catalyst active sites by impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a flow chart of the preparation process of the Pt-Cu / C catalyst according to an embodiment of the present invention.

[0013] Figure 2 This is the CV graph of the Pt-Cu / C catalyst prepared in Example 1 of the present invention under a nitrogen atmosphere.

[0014] Figure 3 This is the LSV diagram of the Pt-Cu / C catalyst prepared in Example 1 of the present invention under an oxygen atmosphere.

[0015] Figure 4 This is a transmission electron micrograph of the Pt-Cu / C catalyst prepared in Example 1 of the present invention.

[0016] Figure 5 This is the XRD pattern of the Pt-Cu / C catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict.

[0018] The process flow chart of the embodiment of the present invention is as follows Figure 1 shown.

[0019] Example 1

[0020] First, weigh 50 mg of ECP600JD and 93.19 mg of Cu(NO₃)₂·3H₂O into a 100 ml beaker. Then, add 30 ml of deionized water to the beaker, stir at 400 rpm for 4 hours, and continue sonicating for 30 minutes. Adjust the pH of the mixed solution to 11 by adding a 10 g / L aqueous solution of NaOH. After aging for 25 minutes, add 41 mg of glucose. Set the water bath to 70°C and hold for 20 minutes. Then, filter, wash with hot water at 80°C, and dry.

[0021] Weigh 252.5mg of a 10% platinum nitrate solution into a 100ml beaker, then add 30ml of deionized water and adjust the pH of the platinum solution to 1.5 with 40g / l sodium hydroxide solution. Add 75mg of carbon-supported cuprous oxide particles, stir at 400rpm for 4h, and continue ultrasonication for 30min; then use 40g / l sodium hydroxide solution to adjust the pH of the platinum-containing mixture to 6.00. After using argon to completely expel oxygen from the autoclave, set the autoclave temperature to 90°C, stir at 250rpm, and hold for 90min. Then, introduce H2 to control the hydrogen partial pressure in the autoclave to approximately 0.5MPa. After the reaction is completed, use argon to completely expel hydrogen from the autoclave, filter and separate, wash with alcohol, and dry to obtain a carbon-supported PtCu3 alloy catalyst.

[0022] The carbon-supported platinum-copper alloy catalyst prepared in this example was subjected to redox testing using a three-electrode system: + / H2 was used as the reference electrode, platinum wire was used as the counter electrode, and the electrolyte was 0.1M HClO4 solution. The purity of nitrogen and oxygen used in the test was not less than 99.99%. The CV pattern of the PtCu3 / C catalyst prepared in this Example 1 under nitrogen atmosphere, the LSV pattern under oxygen atmosphere, the transmission electron microscope pattern and the XRD pattern are shown in Figure 1. Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 shown.

[0023] Example 2

[0024] Weigh 0.5g EC600JD and 0.526g CuCl2·2H2O into a 500ml beaker. Then, add 300ml of deionized water to the beaker. After stirring at 400rpm for 4 hours, continue sonicating for 30 minutes. Adjust the pH of the mixed solution to 12 by adding a 10g / L aqueous solution of NaOH. After aging for 35 minutes, add 0.41g of glucose. Set the water bath to 75°C and hold at 75°C for 25 minutes. Filter, wash with hot water at 80°C, and dry.

[0025] 3.019g of platinum nitrate solution with a platinum mass concentration of 10% was weighed and added to a 500ml beaker, followed by the addition of 300ml of deionized water and the adjustment of the pH of the platinum solution to 4.5 using 40g / l sodium hydroxide solution. 0.71g of carbon-supported cuprous oxide particles was added, and after stirring at 400rpm for 4h, ultrasonication was continued for 30min; the pH was then adjusted to 6.50 using 40g / l sodium hydroxide solution. After using argon to completely expel oxygen from the autoclave, the autoclave temperature was set to 95°C, the stirring speed was 220rpm, the holding time was 100min, and then H2 was introduced to control the hydrogen partial pressure in the autoclave to about 0.75MPa. After the reaction was completed, the hydrogen in the autoclave was completely expelled using argon, the autoclave was filtered, washed with alcohol, and dried to obtain a carbon-supported PtCu2 alloy catalyst.

[0026] The electrochemical test method is the same as that in Example 1. The specific electrochemical test results are shown in Table 1.

[0027] Example 3

[0028] Weigh 1g of XC-72 and 0.946g of Cu(SO4)2·5H2O into a 1000ml beaker. Then, add 600mL of deionized water to the beaker. Stir at 400rpm for 4 hours, then sonicate for 30 minutes. Adjust the pH of the mixture to 10 by adding a 10g / L aqueous solution of NaOH. After aging for 25 minutes, add 0.5g of ascorbic acid. Set the water bath to 85°C and hold at 85°C for 30 minutes. Filter, wash with hot water at 80°C, and dry.

[0029] 7.52g of platinum nitrate solution with a platinum mass concentration of 10% was weighed and added to a 1000ml beaker. 600ml of deionized water and 40g / l sodium hydroxide solution were then added to adjust the pH of the platinum solution to 4.5. 1.26g of carbon-supported cuprous oxide particles were added, and after stirring at 400rpm for 4h, ultrasonication was continued for 30min; then the pH was adjusted to 7.00 using 40g / l sodium hydroxide solution. After using argon to completely remove oxygen from the autoclave, the autoclave temperature was set to 100°C, the stirring speed was 250rpm, and the holding time was 110min. Then, H2 was introduced to control the hydrogen partial pressure in the autoclave to about 1.0MPa. After the reaction was completed, the hydrogen in the autoclave was completely removed with argon, filtered, separated, washed with alcohol, and dried to obtain a carbon-supported PtCu alloy catalyst.

[0030] The electrochemical test method is the same as that in Example 1. The specific electrochemical test results are shown in Table 1.

[0031] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

[0032] Table 1

[0033]

Claims

1. A method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell, characterized in that: The following steps are involved: A. Preparation of Carbon-Supported Cuprous Oxide The copper salt is completely dissolved in pure water, and the concentration of copper in the solution is controlled to be 0.35-2 g / L. A carbon support is then added to the solution, and the mass ratio of the carbon support to the copper is controlled to be 2-4.5:

1. After stirring and impregnating for 4-6 hours, ultrasonic stirring is continued for 30-120 minutes to obtain a copper-containing precursor mixed solution. A sodium hydroxide solution with a concentration of 5 to 20 g / L is added dropwise to a mixed solution containing a copper precursor, and the pH of the mixed solution is adjusted to 10 to 13. After aging for 20 to 60 minutes, a reducing agent is added according to a mass ratio of reducing agent to copper in the mixed solution of 0.4 to 2.5:

1. The temperature is increased to 70 to 90° C., the mixture is reacted for 15 to 60 minutes, and the mixture is filtered and dried to obtain carbon-supported cuprous oxide particles. B. Preparation of Carbon-Supported Platinum-Copper Alloy Catalyst A platinum solution with a platinum concentration of 0.50 to 1.5 g / L is prepared, and a sodium hydroxide solution with a concentration of 20 to 40 g / L is used to adjust the pH of the platinum solution to 1.5 to 5.

0. Then, carbon-supported cuprous oxide particles are added to the platinum solution to obtain a platinum-containing mixed solution. The molar ratio of Cu and Pt in the platinum-containing mixed solution is controlled to be 1 to 3:

1. The solution is stirred and impregnated for a second time for 4 to 10 hours, and ultrasonicated for 30 to 120 minutes. After the ultrasonication is completed, the pH of the platinum-containing mixed solution is adjusted to 5.5 to 8.0 using a sodium hydroxide solution with a concentration of 20 to 40 g / L. The adjusted platinum-containing mixed solution is then added to the solution. The platinum mixed liquid is placed in a reactor, argon is introduced into the reactor, and after the oxygen in the reactor is completely driven out, the temperature is raised to 80-110° C., hydrogen is started to be introduced into the reactor, and the hydrogen partial pressure in the reactor is controlled to be 0.5-1 MPa. The solution is stirred at a rate of 200-350 rpm for 90-120 minutes, and then heating and stirring are stopped. When the temperature in the reactor drops below 50° C., the introduction of hydrogen is stopped and argon is introduced into the reactor to replace the hydrogen. When the hydrogen is completely replaced, solid-liquid separation is performed, and the catalyst is washed with alcohol and dried to obtain a carbon-supported platinum-copper alloy catalyst.

2. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that: The copper salt is at least one of copper nitrate trihydrate, copper chloride dihydrate and copper sulfate pentahydrate.

3. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that: The platinum salt is platinum nitrate.

4. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that: The carbon support is at least one of ECP600JD, EC600JD, and XC-72.

5. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1 is characterized in that: The reducing agent is at least one of ascorbic acid and glucose.

6. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: The sodium hydroxide is an analytical grade reagent.

7. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: The ascorbic acid and glucose are analytically pure reagents.

8. The method for preparing a carbon-supported platinum-copper alloy catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: The purity of the hydrogen is not less than 99.99%; the purity of the argon is not less than 99.99%.

Images