Preparation method of supported platinum-rhodium-copper alloy core-shell nanoelectrocatalyst

Abstract

The application relates to a preparation method and application of a supported platinum-rhodium-copper core-shell nanometer alloy electrocatalyst. The preparation method comprises the following steps: mixing raw materials containing a platinum source, a copper source and a rhodium source, a surfactant and an oleylamine solvent to obtain a mixed solution; the mixed solution is heated to 160-280 DEG C and reacts for 0.5-8 h, and then is cooled; the cooled reaction solution is washed with acetic acid and centrifuged at a speed of not less than 8000 r / min; a product, namely platinum-rhodium-copper alloy nanoparticles, which does not contain the surfactant on the surface, is obtained; the amount of the acetic acid is not less than the volume of the reaction solution; the obtained product and the platinum source are put into the oleylamine solvent, mixed, heated, reacted, cooled and centrifuged to obtain PtRhCu@Pt nanoparticles; the PtRhCu@Pt nanoparticles are mixed with a carbon carrier to obtain a PtRhCu@Pt catalyst. The catalyst prepared by the preparation method has high coating degree of the platinum shell layer on the surface and uniform particle size.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a supported platinum-rhodium-copper core-shell nano-alloy electrocatalyst, which can be used in fuel cells, petrochemicals, high-temperature thermocouples, automotive exhaust purification and other fields. Background Technology

[0002] Platinum, a precious metal, plays a crucial role as a catalyst in most chemical reactions and is irreplaceable in many fields such as fuel cells and automotive exhaust purification. However, its low reserves and high price limit its large-scale commercial application. Taking the cathode oxygen reduction reaction (ORR) catalyst in polymer electrolyte membrane fuel cells as an example, the reaction kinetics are extremely slow, approximately six orders of magnitude slower than the anodic reaction. Platinum is currently the preferred active component for ORR catalysts, but large quantities are still required to ensure high reaction rates and long-term catalytic stability. The excessively high battery cost limits its large-scale commercial application. Studies have shown that introducing additives to form binary or multi-component platinum-based alloys can significantly improve the catalytic activity and lifetime of catalysts while reducing the amount of platinum required. For example, *Science* (DOI: 10.1126 / science.1134569) reported that alloying gold and platinum, utilizing the chemical stability of gold and the high vacancy formation energy of highly alloyed platinum, successfully improved the activity and stability of the catalyst. Based on this, constructing a core-shell structure with PtM alloy as the core and platinum as the shell is an important strategy to further improve the utilization rate of precious metals and reduce costs. The platinum shell on the surface can also prevent the internal non-precious metals from being directly exposed to the harsh reaction environment and inhibit the dissolution of the metal components inside the core.

[0003] Numerous studies have reported that alloy catalysts exhibit the highest catalytic activity when their particle size is approximately 2-5 nm. In PtM@Pt core-shell catalysts, the difference in reduction potential between the Pt source ions and the M metal ions leads to variations in the nucleation and growth rates of Pt and M metals during the reduction preparation process. This results in uneven distribution of metal components and low catalytic activity in the prepared metal nanocatalysts. Furthermore, the construction of the platinum shell faces the challenge of incomplete coating caused by the anisotropic growth of platinum on the PtM surface. Therefore, obtaining a core-shell structure of PtM@Pt with controllable size and high coating degree is a common and major technical challenge in the preparation of highly active and stable platinum-based catalysts. Summary of the Invention:

[0004] To address the aforementioned problems, the present invention aims to provide a supported platinum-rhodium-copper core-shell nano-electrocatalyst and its preparation method. This invention uses oleylamine as the reaction solvent. First, it ensures good dispersion of Pt, Rh, and Cu sources in the reaction solvent. By selecting a long-chain surfactant to protect the crystal nuclei and prevent excessive agglomeration, the particle size of the platinum-rhodium alloy is controlled. Furthermore, the optimization of synthesis parameters such as temperature and time provides a mild reduction environment, enabling the simultaneous deposition of Pt, Rh, and Cu. In addition, thorough washing of the prepared platinum-rhodium-copper alloy with acetic acid prevents anisotropic growth of Pt sources on the surface of the platinum-rhodium-copper alloy during subsequent reduction. Subsequently, the platinum-rhodium-copper alloy particles and Pt sources are dispersed in oleylamine. Upon heating, the oleylamine uniformly reduces the Pt sources onto the surface of the platinum-rhodium-copper alloy. The final prepared metal nanoparticles have a high degree of platinum coating on their surface, with a metal loading range of 10-90 wt%. The metal nanoparticles are uniformly distributed on the carbon support and have an extremely narrow particle size distribution. The particle size of the metal nanoparticles is about 3-5 nm. They have high catalytic activity and high catalytic stability, and are expected to be applied in fields such as fuel cells, petrochemicals, high-temperature thermocouples, automotive exhaust purification, and electrochemical sensors.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing a platinum-rhodium-copper alloy@platinum core-shell catalyst, comprising at least the following steps:

[0007] (1) Mix raw materials containing platinum source, copper source, and rhodium source, surfactant and oleylamine solvent to obtain a mixed solution, heat the mixed solution to 160-280℃, react for 0.5-8h, and then cool.

[0008] (2) Wash the cooled reaction solution from step (1) with acetic acid and then centrifuge at a speed of not less than 8000 r / min to obtain platinum-rhodium-copper alloy nanoparticles with no surfactant on the surface; the amount of acetic acid used is not less than the volume of the reaction solution.

[0009] (3) The product obtained in step (2) and the platinum source were added to the oleylamine solvent, mixed and heated to react, cooled and centrifuged to obtain PtRhCu@Pt nanoparticles.

[0010] (4) PtRhCu@Pt nanoparticles were mixed with carbon support to obtain PtRhCu@Pt catalyst.

[0011] In the above technical solution, the platinum source is further selected from at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, platinum acetylacetonate, and diaminodinitroplatinum;

[0012] The copper source is selected from at least one of copper sulfate, copper acetate, copper oxide, cuprous oxide, copper chloride, cuprous chloride, copper nitrate, copper cyanide, and copper acetylacetonate.

[0013] The rhodium source is selected from at least one of rhodium chlorochloride, potassium rhodium chlorochloride, sodium rhodium chlorochloride, and rhodium acetylacetone.

[0014] The surfactant is selected from one or more of the following: hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, Briji-76, Briji-700, P-123, F-127, polyvinyl alcohol, polyethyleneimine, hexadecyltrimethylammonium chloride, didecyldimethylammonium chloride, 1-octadecene, and dodecyltrimethylammonium chloride.

[0015] The carbon support is selected from one or more of carbon black, carbon nanotubes, carbon fibers, graphene oxide reduced from graphene, and mesoporous carbon, and the specific surface area of ​​the support is 200–2500 m². 2 / g;

[0016] In the above technical solution, further, in the mixed solution of step (1), the mass concentration of platinum is 1.0-36 g / L, the mass fraction of copper is 0.5-20 g / L, the mass fraction of rhodium is 0.5-20 g / L, the molar ratio of platinum to copper is (2:1)-(6:1), the molar ratio of platinum to rhodium is (6:1)-(12:1); and the content of surfactant is 0.5-120 g / L.

[0017] In the above technical solution, the platinum source in step (3) is the same as or different from the platinum source in step (1); the amount of platinum source used in step (3) is the same as the amount of platinum source used in step (1).

[0018] In the above technical solution, further, in step (3), the temperature of the oleylamine solvent is 120-140℃, the temperature of the heating reaction is 150-280℃, the reaction time is 0.5-8h, and the centrifugal speed is not less than 8000r / min.

[0019] In the above technical solution, further, in step (4), PtRhCu@Pt nanoparticles are dispersed in an alcohol solution and then added dropwise to an alcohol solution containing a carbon support. The mixture is ultrasonicated or stirred for 1-4 hours, centrifuged at a speed greater than 8000 r / min, and the catalyst is dried and collected.

[0020] In the above technical solution, the alcohol solution is further comprising one or a mixture of methanol, ethanol, ethylene glycol, propylene glycol, glycerol, butanediol, and isopentylene glycol;

[0021] In step (4), the mass ratio of PtRhCu@Pt nanoparticles to carbon support is (2:8) to (9:1).

[0022] In the above technical solution, the PtRhCu@Pt particles obtained in step (3) are further dispersed in acetic acid and washed, centrifuged at a speed of not less than 8000 r / min, dried and ground to obtain PtRhCu@Pt nanoparticles with clean surfaces and no surfactants.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (a) The present invention obtains a platinum-rhodium-copper alloy by mixing at a suitable temperature, and then washes the platinum-rhodium-copper alloy with acetic acid and then coats it. The resulting PtRhCu@Pt core-shell nanoparticles are uniformly distributed and have an extremely narrow particle size distribution, with a particle size of about 3-5 nanometers.

[0025] (b) The present invention uses glacial acetic acid to wash before reducing the platinum source to form a platinum shell, which is simple and quick to collect the alloy product, and achieves a clean product surface without oil and amine residue. This ensures that the platinum species grow uniformly on the surface of the alloy particles, thereby achieving uniform coating of the platinum-rhodium-copper alloy by the platinum shell.

[0026] (c) The catalyst prepared by this invention has high catalytic activity and high catalytic stability, and can be used in fuel cells, electrochemical sensors, high-temperature thermocouples and other fields. Attached image description:

[0027] Figure 1 This is the particle size statistical result of PtRhCu@Pt / XC-72 obtained in Example 1 of the present invention;

[0028] Figure 2 This is a comparison of the CV curves of the catalyst PtRhCu@Pt / XC-72 and PtRhCu / XC-72 obtained in Example 1 of this invention;

[0029] Figure 3 This is the LSV curve obtained by testing PtRhCu@Pt / XC-72RDE in Example 3 of the present invention;

[0030] Figure 4 This is a graph showing the change in mass activity during the accelerated durability test of PtRhCu@Pt / XC-72RDE obtained in Example 3 of this invention.

[0031] Figure 5 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Comparative Example 1 of this invention;

[0032] Figure 6 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Comparative Example 2 of this invention;

[0033] Figure 7 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Example 1 of the present invention;

[0034] Figure 8 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Example 2 of the present invention;

[0035] Figure 9 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Example 3 of the present invention;

[0036] Figure 10 This is a TEM image of PtRhCu@Pt / XC-72 obtained in Example 4 of the present invention. Detailed Implementation

[0037] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0038] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased commercially; among them, TKK20wt% commercial platinum carbon was purchased from Tanaka Precious Metals Co., Ltd. of Japan, and its composition includes 20wt% platinum and 80wt% carbon (carbon type: XC-72).

[0039] Example 1

[0040] First, 5 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 3 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 8 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 200°C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 rpm for 10 minutes to obtain a black substrate. The black substrate was dispersed in 8 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 rpm. The obtained substrate was dried, ground, and then dispersed with 5 mg of platinum acetylacetone in 10 ml of oleylamine at 120°C. The mixture was heated to 200°C and reacted for 1 hour, then allowed to cool naturally. The resulting black solution was centrifuged at 8000 rpm for 10 minutes to obtain a black substrate. The black substrate was dispersed in 10 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 rpm to obtain a black substrate. The obtained substrate was then dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was collected by centrifugation at a speed greater than 8000 r / min and dried under vacuum at 60 °C to obtain PtRhCu@Pt catalyst with a particle size of about 4 nm.

[0041] Comparing the prepared catalyst with the uncoated platinum sample, it can be seen that the electrochemical active area of ​​the sample in Example 1 is much larger than that of the uncoated platinum sample, indicating that the sample surface is occupied by platinum atoms, and PtRhCu@Pt / C is indeed a core-shell structure with a platinum-coated surface.

[0042] Comparative Example 1

[0043] First, 5 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 3 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 8 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 200°C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The obtained substrate was dried, ground, and then dispersed with 5 mg of platinum acetylacetone in 10 ml of oleylamine at 120°C. The mixture was heated to 200°C and reacted for 1 hour, then allowed to cool naturally. The resulting black solution was centrifuged at a speed greater than 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 10 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min to obtain a black substrate. Finally, the obtained substrate was dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was collected by centrifugation at a speed greater than 8000 r / min and dried under vacuum at 60 °C to obtain the PtRhCu@Pt catalyst.

[0044] Depend on Figure 5 and Figure 7 As can be seen, in the preparation process of this invention, the platinum-rhodium-copper alloy is first washed with acetic acid before coating, resulting in PtRhCu@Pt / XC-72 particles with a diameter of 4-5 nm and a spherical shape. In contrast, PtRhCu@Pt / XC-72 particles obtained by coating the platinum-rhodium-copper alloy without acetic acid washing exhibit significant differences in particle size, ranging from 3-10 nm, and vary in shape, not being spherical. This comparison demonstrates that acetic acid treatment ensures uniform platinum coating on the surface of the platinum-rhodium-copper alloy.

[0045] Example 2

[0046] First, 10 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 6 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 20 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 200°C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min. The obtained substrate was dried, ground, and then dispersed with 10 mg of platinum acetylacetone in 10 ml of oleylamine at 120°C. After ultrasonication for 60 minutes, the temperature was raised to 200°C and reacted for 1 hour. After cooling naturally, the resulting black solution was centrifuged at a speed greater than 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min to obtain a black substrate. The obtained substrate was then dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was collected by centrifugation at a speed greater than 8000 r / min and dried under vacuum at 60 °C to obtain PtRhCu@Pt catalyst with a particle size of about 4 nm.

[0047] Comparative Example 2

[0048] First, 10 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 6 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 20 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 320 °C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min. The obtained substrate was dried, ground, and then dispersed with 10 mg of platinum acetylacetone in 10 ml of oleylamine at 120 °C. After ultrasonication for 60 minutes, the temperature was raised to 200 °C and reacted for 1 hour. After cooling naturally, the resulting black solution was centrifuged at a speed greater than 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min to obtain a black substrate. The obtained substrate was then dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was collected by centrifugation at a speed greater than 8000 r / min and dried under vacuum at 60 °C to obtain the PtRhCu@Pt catalyst.

[0049] Depend on Figure 6 and Figure 8It can be seen that the platinum source, rhodium source, and copper source react at appropriate temperatures to ensure the uniformity and small size of the final PtRhCu@Pt particles; while the PtRhCu@Pt particles obtained by reacting at excessively high temperatures are severely agglomerated, with the smallest size being about 4 nm and the largest size reaching about 50 nm. Figure 8 The sample particles prepared in this way are spherical, indicating that the platinum shell is uniformly coated on the platinum-rhodium-copper core.

[0050] Example 3:

[0051] First, 10 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 6 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 20 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 250 °C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min. The obtained substrate was dried, ground, and then dispersed with 10 mg of platinum acetylacetone in 10 ml of oleylamine at 120 °C. After ultrasonication for 60 minutes, the temperature was raised to 200 °C and reacted for 1 hour. After cooling naturally, the resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min to obtain a black substrate. The obtained substrate was then dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was then centrifuged at a speed greater than 8000 r / min, collected, and dried under vacuum at 60 °C to obtain the PtRhCu@Pt catalyst. Figure 9 It can be seen that the platinum shell is uniformly coated on the platinum-rhodium-copper core.

[0052] The obtained catalyst was evaluated for electrochemical activity using a rotating disk electrode. The specific steps were as follows: Approximately 5 mg of the PtRhCu@Pt / XC-72 catalyst prepared in Example 3 was accurately weighed and mixed with 30 μL of Nafion (5 wt%) solution and 5 mL of ethanol. The mixture was ultrasonically dissolved to obtain a uniformly dispersed catalyst slurry. Then, 10 μL of the catalyst slurry was transferred and coated onto a glassy carbon rotating disk electrode with an area of ​​0.19625 square centimeters. After drying, the working electrode was obtained. The oxygen reduction catalytic activity of the catalyst was tested by scanning from 0 V to 1.2 V at a scan rate of 10 mV / s in an oxygen-saturated 0.1 M perchloric acid aqueous solution to obtain the oxygen reduction curve. According to... Figure 3The calculated specific mass activity of the PtRhCu@Pt / XC-72 catalyst at an electrode potential of 0.9 V (vs. RHE) for the oxygen reduction reaction was 900 mA / mgPt, significantly better than that of the 20wt% TKK commercial Pt / C sample (170 mA / mgPt). The PtRhCu@Pt / XC-72 catalyst was scanned in an oxygen-saturated 0.1M perchloric acid aqueous solution at a scan rate of 100 mV / s from 0.6 V to 1.1 V and back to 0.6 V as one cycle. Every 10,000 cycles, an LSV scan was performed using the method described above to determine the specific mass activity at the current cycle number. A total of 30,000 cycles were performed. The obtained mass activities at each stage are shown below. Figure 4 As shown, after 30,000 accelerated durability cycles, the catalyst's mass activity decreased by only about 15%, indicating high stability.

[0053] Example 4

[0054] First, 10 mg of platinum acetylacetone, 1.6 mg of rhodium acetylacetone, 6 mg of copper acetylacetone, 15 mg of cetyltrimethylammonium bromide, and 20 ml of oleylamine were added to a 25 ml flask. After ultrasonic dispersion for 60 minutes, the mixture was stirred at 220 °C for 2 hours and then allowed to cool naturally. The resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min. The obtained substrate was dried, ground, and then dispersed with 10 mg of platinum acetylacetone in 10 ml of oleylamine at 120 °C. After ultrasonication for 60 minutes, the temperature was raised to 200 °C and reacted for 1 hour. After cooling naturally, the resulting black solution was centrifuged at 8000 r / min for 10 minutes to obtain a black substrate. The black substrate was dispersed in 20 ml of glacial acetic acid and centrifuged again at a speed greater than 8000 r / min to obtain a black substrate. The obtained substrate was then dispersed in 10 ml of ethanol. 35 mg of XC-72 carbon powder was dispersed in 10 ml of ethanol and stirred while the reaction product dispersed in 10 ml of ethanol was slowly added dropwise. After the addition was complete, stirring was continued for 1 hour. The product was then centrifuged at a speed greater than 8000 r / min, collected, and dried under vacuum at 60 °C to obtain the PtRhCu@Pt catalyst. Figure 10 It can be seen that the platinum shell is uniformly coated on the platinum-rhodium-copper core.

Claims

1. A method for preparing a platinum-rhodium-copper alloy@platinum core-shell catalyst, characterized in that, At least the following steps are included: (1) Mix raw materials containing platinum source, copper source, and rhodium source, surfactant and oleylamine solvent to obtain a mixed solution, heat the mixed solution to 160-280℃, react for 0.5-8h, and then cool. (2) Wash the cooled reaction solution from step (1) with acetic acid and then centrifuge at a speed of not less than 8000 r / min to obtain platinum-rhodium-copper alloy nanoparticles with no surfactant on the surface; the amount of acetic acid used is not less than the volume of the reaction solution. (3) The product obtained in step (2) and the platinum source were added to the oleylamine solvent, mixed and heated to react, cooled and centrifuged to obtain PtRhCu@Pt nanoparticles. (4) PtRhCu@Pt nanoparticles were mixed with carbon support to obtain PtRhCu@Pt catalyst.

2. The preparation method according to claim 1, characterized in that, The platinum source is selected from at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, platinum acetylacetonate, and diaminodinitroplatinum; The copper source is selected from at least one of copper sulfate, copper acetate, copper oxide, cuprous oxide, copper chloride, cuprous chloride, copper nitrate, copper cyanide, and copper acetylacetonate. The rhodium source is selected from at least one of rhodium chlorochloride, potassium rhodium chlorochloride, sodium rhodium chlorochloride, and rhodium acetylacetone. The surfactant is selected from hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, Briji-76, Briji-700, P-123, F-127, polyvinyl alcohol, polyethyleneimine, hexadecyltrimethylammonium chloride, didecyldimethylammonium chloride, and 1-octadecene. One or more of dodecyltrimethylammonium chloride; The carbon support is selected from one or more of carbon black, carbon nanotubes, carbon fibers, graphene, and reduced graphene oxide, and the specific surface area of ​​the support is 200–2500 m². 2 / g.

3. The preparation method according to claim 1, characterized in that, In the mixed solution of step (1), the mass concentration of platinum is 1.0-36 g / L, the mass fraction of copper is 0.5-20 g / L, the mass fraction of rhodium is 0.5-20 g / L, the molar ratio of platinum to copper is (2:1)-(6:1), and the molar ratio of platinum to rhodium is (6:1)-(12:1); the content of surfactant is 0.5-120 g / L.

4. The preparation method according to claim 1, characterized in that, The platinum source in step (3) is the same as or different from the platinum source in step (1); the amount of platinum source used in step (3) is the same as the amount of platinum source used in step (1).

5. The preparation method according to claim 1, characterized in that, In step (3), the temperature of the oleylamine solvent is 120-140℃, the temperature of the heating reaction is 150-280℃, the reaction time is 0.5-8h, and the centrifugal speed is not less than 8000r / min.

6. The preparation method according to claim 1, characterized in that, In step (4), PtRhCu@Pt nanoparticles are dispersed in an alcohol solution and then added dropwise to an alcohol solution containing a carbon support. The mixture is ultrasonicated or stirred for 1-4 hours, centrifuged at a speed greater than 8000 r / min, and dried to collect the catalyst.

7. The preparation method according to claim 6, characterized in that, The alcohol solution is one or a mixture of methanol, ethanol, ethylene glycol, propylene glycol, glycerol, butanediol, and isopentylene glycol; In step (4), the mass ratio of PtRhCu@Pt nanoparticles to carbon support is (2:8) to (9:1).

8. The preparation method according to claim 1, characterized in that, The PtRhCu@Pt particles obtained in step (3) are dispersed in acetic acid, washed, centrifuged at a speed of not less than 8000 r / min, dried, and ground to obtain PtRhCu@Pt nanoparticles with clean surfaces and no surfactants.

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