Pd-coated PdPtCuNiCoZn octahedral nano high-entropy alloy as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and particularly discloses a Pd-coated PdPtCuNiCoZn octahedral nano high-entropy alloy as well as a preparation method and application of the Pd-coated PdPtCuNiCoZn octahedral nano high-entropy alloy. The Pd-coated PdPtCuNiCoZn octahedral nano high-entropy alloy provided by the invention is a core-shell octahedral nano crystal which takes Pd as a core and takes Pd, Pt, Cu, Ni, Co and Zn as a shell layer. According to the Pd-coated PdPtCuNiCoZn octahedral nano high-entropy alloy provided by the invention, the dosage of noble metals Pt and Pd is greatly reduced, and meanwhile, through the synergistic effect of various transition metals and noble metals, the preparation cost of a catalyst is reduced, and the adsorption / desorption process of OER and ORR reaction intermediates is optimized by effectively regulating and controlling an electronic structure, so that the performance of the catalyst is improved. And the catalytic activity and durability of the catalyst are obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a Pd@PdPtCuNiCoZn octahedral nanometer high-entropy alloy and a preparation method and application thereof. BACKGROUND

[0002] The rechargeable zinc-air battery (Zn-O2) has a wide application prospect in the field of battery technology as a high-energy-density energy storage device. Its working principle is that in the discharge process, the zinc anode releases electrons through oxidation reaction, and oxygen is reduced to hydroxide or water on the cathode; while in the charging process, zinc ions are reduced to metallic zinc, and the cathode releases oxygen through oxygen evolution reaction (OER). Since the discharge and charge of the zinc-air battery involve the reduction and evolution of oxygen, the cathode needs to have the ability to simultaneously catalyze the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Both OER and ORR involve four-electron transfer, and the reaction kinetics is relatively slow, which greatly restricts the charge-discharge power and cycle stability of the battery. Therefore, developing a high-efficiency dual-function catalyst to improve the performance of the zinc-air battery is one of the key technologies to realize its wide application.

[0003] Currently, in the research of zinc-air battery cathode catalysts, alloyed catalysts have attracted widespread attention. By alloying noble metals (such as platinum and palladium) with transition metals (such as cobalt, nickel, copper, etc.), researchers can significantly reduce the amount of noble metal while maintaining high catalytic activity, reducing cost and improving the stability of the catalyst. For example, palladium (Pd) and platinum (Pt) based alloy catalysts exhibit good performance in ORR, but their cost is high and they may face the problem of noble metal dissolution and deactivation during long-term use. Therefore, it is of great significance to develop a dual-function catalyst that can simultaneously exhibit excellent OER and ORR activity. SUMMARY

[0004] In view of this, the present application provides a Pd@PdPtCuNiCoZn octahedral nanometer high-entropy alloy and a preparation method and application thereof.

[0005] To solve the above technical problems, the technical solution provided by the present application is: The present application provides a Pd@PdPtCuNiCoZn octahedral nanometer high-entropy alloy, which is a core-shell octahedral nanocrystal with Pd as the core and Pd, Pt, Cu, Ni, Co and Zn as the shell.

[0006] Compared to existing technologies, this invention introduces inexpensive transition metals such as copper, nickel, cobalt, and zinc, along with palladium and platinum, to prepare an octahedral high-entropy nano-alloy with a core-shell structure, significantly reducing the amount of precious metals used and the cost of the catalyst. In the Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy provided by this invention, inexpensive metals with low electronegativity, such as copper, nickel, and cobalt, undergo electron transfer to the precious metal Pd / Pt, effectively reducing the d-band center of Pd / Pt, thereby optimizing its adsorption strength for reaction intermediates and avoiding catalyst poisoning caused by excessive adsorption. Applying these metals to the catalyst significantly improves its intrinsic activity. Simultaneously, due to the small atomic radii of copper, nickel, and cobalt, their incorporation into the Pd / Pt lattice introduces compressive strain, further optimizing the electronic structure of the high-entropy nano-alloy. Furthermore, zinc volatilization creates highly active defect sites. The combined effect of these elements greatly enhances the structural stability and dissolution resistance of the Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy, further improving the catalytic performance of the catalyst.

[0007] The Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy provided by this invention significantly reduces the amount of noble metals Pt and Pd used. Through the synergistic effect of multiple transition metals and noble metals, it not only reduces the preparation cost of the catalyst, but also significantly improves the catalytic activity and durability of the catalyst by effectively controlling the electronic structure and optimizing the adsorption / desorption process of OER and ORR reaction intermediates.

[0008] Preferably, the Pd@PdPtCuNiCoZn octahedral nano-high entropy alloy comprises the following components in atomic percentage: Pd: 5%~35%, Pt: 5%~35%, Cu: 5%~35%, Ni: 5%~35%, Co: 5%~35%, and Zn: 5%~35%.

[0009] More preferably, the Pd@PdPtCuNiCoZn octahedral nano-high entropy alloy comprises the following components in atomic percentage: Pd: 12.6%, Pt: 27.5%, Cu: 8.6%, Ni: 34.6%, Co: 10.8%, and Zn: 5.9%.

[0010] This invention provides a method for preparing the above-mentioned Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy, comprising the following steps: S1. Dissolve the halide salt and polyvinylpyrrolidone in a first alcohol solvent to obtain a mixture; S2. Disperse palladium, platinum, copper, nickel, cobalt and zinc sources in the mixture, and then perform microwave treatment to obtain Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy.

[0011] Compared to existing technologies, the method for preparing Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloys provided by this invention utilizes halide salts as morphology guiding agents. These halide salts exhibit strong adsorption on the {100} crystal planes (cubic faces). When adsorbed on the {100} crystal planes, they significantly reduce the surface energy of these planes, making it difficult for metal atoms to deposit on them. Conversely, the adsorption of halide salts on the {111} crystal planes (octahedral faces) is weaker, and metal atoms preferentially decrease and deposit on the {111} crystal planes, which have higher surface energy and faster growth. This selective passivation of crystal planes allows for the reduction and deposition of {11} crystals during crystal growth. 1) The crystal planes gradually expand, ensuring the formation of an octahedral structure in the high-entropy nano-alloy. Polyvinylpyrrolidone (PVP), as a colloidal stabilizer, prevents the aggregation of Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloys. The long-chain molecules of PPVP can adsorb onto the surface of the Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy, forming an organic protective layer, thus effectively preventing the aggregation of the high-entropy nano-alloy. This invention, through the synergistic effect of halide salts and PPVP, not only ensures that the obtained high-entropy nano-alloy has an octahedral morphology but also avoids the aggregation problem.

[0012] In this invention, the reduction potential of the palladium source is relatively high. Under microwave conditions, Pd 2+ It is preferentially reduced, rapidly nucleates, and forms a core; while Pt 4+ Cu 2+ Ni 2+ Co 2+ and Zn 2+ The reduction potential of Pd is relatively low, and it will deposit on the Pd core to form an octahedral high-entropy nano-alloy with Pd as the core and Pd, Pt, Cu, Ni, Co and Zn as the shell. In addition, when Pd is preferentially reduced to form the core, polyvinylpyrrolidone is adsorbed on the core surface, inhibiting the Ostwald ripening phenomenon or mutual agglomeration of the core, which further ensures the size uniformity of the Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy and lays the foundation for the subsequent uniform shell growth.

[0013] The method for preparing Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloys provided by this invention utilizes a microwave-assisted polyol method to synthesize octahedral high-entropy nano-alloys. During the preparation process, the morphology and metal element distribution of the high-entropy nano-alloys can be effectively controlled, resulting in an octahedral structure with high catalytic activity. This structure not only increases the surface active sites of the catalyst but also improves its stability, reduces the amount of precious metals required, and enhances the bifunctional catalytic performance of ORR and OER. Furthermore, this method involves rapid solution synthesis via microwave irradiation, is simple to operate, and operates under mild experimental conditions, making it suitable for large-scale production.

[0014] Preferably, in S1, the halide is potassium bromide (KBr).

[0015] Preferably, in S1, the first alcohol solvent is tetraethylene glycol (TEG).

[0016] Preferably, in S1, the polyvinylpyrrolidone is polyvinylpyrrolidone K30.

[0017] Preferably, in S1, the ratio of polyvinylpyrrolidone to the first alcohol solvent is (200~250) mg: (25~35) mL.

[0018] More preferably, in S1, the ratio of the amount of polyvinylpyrrolidone to the first alcohol solvent is (210~230) mg: (28~32) mL.

[0019] For example, in S1, the halide salt and polyvinylpyrrolidone are added to the first alcohol solvent and stirred at a speed of 600 rpm to 650 rpm. After dissolution, the mixture is sonicated at room temperature for 30 to 120 minutes. The sonication conditions are not limited here, and conventional operating methods known to those skilled in the art can be used.

[0020] Preferably, in S2, the palladium source is palladium chloride.

[0021] Preferably, in S2, the platinum source is chloroplatinic acid.

[0022] Preferably, in S2, the copper source is copper chloride.

[0023] Preferably, in S2, the nickel source is nickel chloride.

[0024] Preferably, in S2, the cobalt source is cobalt chloride.

[0025] Preferably, in S2, the zinc source is zinc chloride.

[0026] Preferably, in S2, the mass ratio of the palladium source, platinum source, copper source, nickel source, cobalt source, zinc source, halide salt and polyvinylpyrrolidone is (17~20):(20~25):(10~15):(10~15):(10~15):(10~15):(400~500):(200~250).

[0027] By selecting the mass ratio of palladium, platinum, copper, nickel, cobalt, zinc, halide salt, and polyvinylpyrrolidone, this invention can further control the morphology of Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloys, thereby improving the catalytic activity of the catalyst.

[0028] More preferably, in S2, the mass ratio of the palladium source, platinum source, copper source, nickel source, cobalt source, zinc source, halide salt and polyvinylpyrrolidone is 17.73:20.49:13.45:12.96:12.98:13.63:476:222.

[0029] Preferably, in S2, the power of the microwave processing is 600~800W.

[0030] Preferably, in S2, the microwave treatment time is 60~240s.

[0031] More preferably, in S2, the microwave treatment time is 60~180s.

[0032] More preferably, in S2, the microwave processing time is 120~180s.

[0033] For example, in S2, the dispersion can be achieved by ultrasonic treatment, with a frequency of 32~48kHz and a duration of 30~40min.

[0034] It should be further noted that in S2, after the microwave treatment is completed, the reaction product is cooled to room temperature, the black product is collected by centrifugation, washed with a mixed solution of acetone and ethanol, and dried to constant weight.

[0035] For example, the centrifugation conditions are: a rotation speed of 9600~10000 rpm.

[0036] For example, in the mixed solution of acetone and ethanol, the volume ratio of acetone to ethanol is 1:(4~5).

[0037] For example, the number of times the washing is performed is 2 to 5.

[0038] For example, the drying conditions are: a temperature of 55~65℃ and a time of 11.5~12.5h.

[0039] This invention provides a Pd@PdPtCuNiCoZn / C catalyst, comprising carbon black and Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy supported on the carbon black.

[0040] Preferably, the mass ratio of the Pd@PdPtCuNiCoZn octahedral nano high-entropy alloy to carbon black is 2:(2.8~3.2).

[0041] This invention provides a method for preparing the above-mentioned Pd@PdPtCuNiCoZn / C catalyst, comprising the following steps: The weighed carbon black and Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy were dispersed in a second alcohol solvent, and after solid-liquid separation, they were calcined to obtain the Pd@PdPtCuNiCoZn / C catalyst.

[0042] Preferably, the second alcohol solvent is anhydrous ethanol.

[0043] Preferably, the mass-to-volume ratio of the carbon black and the second alcohol solvent is 1 mg: (1~2) mL.

[0044] More preferably, the mass-to-volume ratio of the carbon black and the second alcohol solvent is 1 mg: 1 mL.

[0045] It should be further noted that the dispersion can be achieved by ultrasonic treatment, with a frequency of 32~48kHz and a duration of 30~120min.

[0046] Preferably, the calcination temperature is 180~400℃.

[0047] More preferably, the calcination temperature is 180~200℃.

[0048] Preferably, during the calcination, the temperature is increased to 180-400°C at a heating rate of 1-10°C / min.

[0049] Further preferably, the temperature is increased to 180-400℃ at a heating rate of 2-5℃ / min.

[0050] Preferably, the calcination time is 1 to 4 hours.

[0051] More preferably, the calcination time is 1-2 hours.

[0052] For example, the solid-liquid separation is performed by centrifugation, and the centrifuged product is dried after centrifugation.

[0053] This invention provides the application of the above-mentioned Pd@PdPtCuNiCoZn / C catalyst in zinc-air batteries.

[0054] This invention provides the application of the above-mentioned Pd@PdPtCuNiCoZn / C catalyst in electrocatalytic oxygen evolution reaction and oxygen reduction reaction.

[0055] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention introduces inexpensive transition metals such as Co, Ni, Cu, and Zn with noble metals Pd and Pt to prepare an octahedral nano-high-entropy alloy, which significantly reduces the amount of noble metals used and the cost of the catalyst. There is a subtle synergistic effect among the elements in the octahedral nano-high-entropy alloy: the inexpensive metals optimize the electronic structure of Pd / Pt through electron transfer, weakening its excessive adsorption of reaction intermediates and improving intrinsic activity; simultaneously, the highly active defect sites created by lattice strain and Zn volatilization further enhance the catalytic performance; and the high-entropy environment significantly improves structural stability. This multi-synergistic mechanism ensures the excellent catalytic performance of the Pd@PdPtCuNiCoZn / C catalyst while also achieving "cost reduction and efficiency improvement". The OER overpotential of the Pd@PdPtCuNiCoZn / C catalyst prepared in this invention in 1.0M KOH solution is 354mV@10mA·cm. -2 The ORR half-wave potential in 0.1M KOH solution reaches 0.808V.

[0056] (2) The present invention has successfully achieved precise control of the morphology of multi-element high-entropy alloys through microwave-assisted polyol method. When used in catalysts, the nanoscale structure increases the specific surface area of ​​the catalyst and increases the exposed active sites, thereby further improving the catalytic activity. Moreover, the structural design effectively improves the stability and durability of the catalyst and maintains a high catalytic effect during long-term use.

[0057] (3) The preparation method provided by the present invention adopts microwave-assisted polyol method and low-temperature calcination process. These methods do not rely on high temperature and high pressure equipment, are simple to operate, have mild experimental conditions, and are suitable for large-scale production. Compared with traditional high temperature melting, carbothermal reduction and other methods, they have higher production efficiency and lower equipment cost, which meets the needs of industrial production. Attached Figure Description

[0058] Figure 1 The X-ray diffraction patterns of the nanocrystals prepared in Example 1 and Comparative Examples 1-6 of this invention are shown below. Figure 2 TEM image of Pd@PdPtCu nanocrystals provided in Comparative Example 1 of this invention; Figure 3 This is a TEM image of the Pd@PdPtCuCo nanocrystals provided in Comparative Example 2 of this invention; Figure 4 This is a TEM image of the Pd@PdPtCuNi nanocrystals provided in Comparative Example 3 of this invention; Figure 5 This is a TEM image of the Pd@PdPtCuZn nanocrystals provided in Comparative Example 4 of this invention; Figure 6This is a TEM image of the Pd@PdPtCuNiCo nanocrystals provided in Comparative Example 5 of this invention; Figure 7 This is a TEM image of the Pd@PdPtCuNiZn nanocrystals provided in Comparative Example 6 of this invention; Figure 8 This is a TEM image of the Pd@PdPtCuNiCoZn nanocrystals provided in Example 1 of the present invention; Figure 9 The elemental mapping distribution diagram of Pd@PdPtCuNiCoZn nanocrystals provided in Embodiment 1 of the present invention; Figure 10 The OER performance of the catalysts provided in Example 1 and Comparative Examples 1-6 of this invention in 1M KOH solution is shown in the graph. Figure 11 ORR performance of the catalysts provided in Example 1 and Comparative Examples 1-6 of this invention in 0.1M KOH solution; Figure 12 The performance diagram of the zinc-air battery of the catalyst provided in Example 1 of the present invention in a mixed solution of 6M KOH and 0.2M Zn(CH3COO)2. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0060] Example 1 This embodiment provides a method for preparing a Pd@PdPtCuNiCoZn / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid was added in the form of an 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution was 256 μL), 13.45 mg copper chloride, 12.96 mg nickel chloride, 12.98 mg cobalt chloride and 13.63 mg zinc chloride to the above beaker, and sonicate for 2 hours until the mixture is homogeneous; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNiCoZn nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNiCoZn nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNiCoZn nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuZnCoNi / C catalyst.

[0061] Example 2 This embodiment provides a method for preparing a Pd@PdPtCuNiCoZn / C catalyst, comprising the following steps: S1: Dissolve 495 mg KBr and 245 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 650 rpm and sonicate for 30 min. S2: Add 17mg palladium chloride, 20mg chloroplatinic acid (chloroplatinic acid is added in the form of 8wt% chloroplatinic acid solution, the chloroplatinic acid solution is 250μL), 15mg copper chloride, 14.8mg nickel chloride, 10mg cobalt chloride and 10mg zinc chloride to the above beaker, and sonicate for 2 hours until mixed evenly; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave it for 60 seconds at 700W. S4: After naturally cooling to room temperature, centrifuge at 9600 rpm for 5 min, collect the precipitate, and wash it 4 times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNiCoZn nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNiCoZn nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNiCoZn nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 180 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuZnCoNi / C catalyst.

[0062] Example 3 This embodiment provides a method for preparing a Pd@PdPtCuNiCoZn / C catalyst, comprising the following steps: S1: Dissolve 410 mg KBr and 200 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 650 rpm and sonicate for 30 min. S2: Add 20mg palladium chloride, 25mg chloroplatinic acid (chloroplatinic acid is added in the form of 8wt% chloroplatinic acid solution, the chloroplatinic acid solution is 310μL), 10mg copper chloride, 10mg nickel chloride, 15mg cobalt chloride and 15mg zinc chloride to the above beaker, and sonicate for 2 hours until mixed evenly; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave it for 100 seconds at 700W. S4: After naturally cooling to room temperature, centrifuge at 9600 rpm for 5 min, collect the precipitate, and wash it 5 times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNiCoZn nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNiCoZn nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNiCoZn nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the temperature was increased to 400℃ at a heating rate of 5℃ / min and calcined in air atmosphere for 2 h to obtain the Pd@PdPtCuZnCoNi / C catalyst.

[0063] Comparative Example 1 This comparative example provides a method for preparing a Pd@PdPtCu / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid was added in the form of an 8 wt% chloroplatinic acid solution, which was 256 μL) and 13.45 mg copper chloride to the above beaker and sonicate for 2 hours until the mixture is homogeneous. S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCu nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCu nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCu nanocrystals to Vulcan XC-72R carbon black was 2:3), centrifuged, vacuum dried, and then heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCu / C catalyst supported on carbon black.

[0064] Comparative Example 2 This comparative example provides a method for preparing a Pd@PdPtCuCo / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid is added in the form of 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution is 256 μL), 13.45 mg copper chloride and 12.98 mg cobalt chloride to the above beaker, and sonicate for 2 hours until the mixture is homogeneous; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuCo nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuCo nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuCo nanocrystals to Vulcan XC-72R carbon black was 2:3). After vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuCo / C catalyst supported on carbon black.

[0065] Comparative Example 3 This comparative example provides a method for preparing a Pd@PdPtCuNi / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid is added in the form of 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution is 256 μL), 13.45 mg copper chloride and 12.96 mg nickel chloride to the above beaker, and sonicate for 2 hours until mixed evenly; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNi nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNi nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNi nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuNi / C catalyst supported on carbon black.

[0066] Comparative Example 4 This comparative example provides a method for preparing a Pd@PdPtCuZn / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid is added in the form of 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution is 256 μL), 13.45 mg copper chloride and 13.63 mg zinc chloride to the above beaker, and sonicate for 2 hours until the mixture is homogeneous; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuZn nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuZn nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuZn nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuZn / C catalyst supported on carbon black.

[0067] Comparative Example 5 This comparative example provides a method for preparing a Pd@PdPtCuNiCo / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid was added in the form of an 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution was 256 μL), 13.45 mg copper chloride, 12.96 mg nickel chloride and 12.98 mg cobalt chloride to the above beaker, and sonicate for 2 hours until the mixture is homogeneous. S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNiCo nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNiCo nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNiCo nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuNiCo / C catalyst supported on carbon black.

[0068] Comparative Example 6 This comparative example provides a method for preparing a Pd@PdPtCuNiZn / C catalyst, comprising the following steps: S1: Dissolve 476 mg KBr and 222 mg PVP (K30) in a 50 mL beaker containing 30 mL of tetraethylene glycol at 600 rpm and sonicate for 30 min. S2: Add 17.73 mg palladium chloride, 20.49 mg chloroplatinic acid (chloroplatinic acid is added in the form of 8 wt% chloroplatinic acid solution, the chloroplatinic acid solution is 256 μL), 13.45 mg copper chloride, 12.96 mg nickel chloride and 13.63 mg zinc chloride to the above beaker, and sonicate for 2 hours until mixed evenly; S3: Transfer the beaker containing the mixed solution to a microwave oven and microwave at 700W for 3 minutes; S4: After naturally cooling to room temperature, centrifuge at 10,000 rpm for 5 min, collect the precipitate, and wash it three times with a 1:4 volume ratio acetone / ethanol mixed solution by centrifugation. Then, vacuum dry at 60℃ to obtain Pd@PdPtCuNiZn nanocrystals. S5: Using Vulcan XC-72R carbon black as a support, 10 mg of Pd@PdPtCuNiZn nanocrystals and 15 mg of Vulcan XC-72R carbon black were ultrasonically mixed in 25 mL of ethanol solvent (the mass ratio of Pd@PdPtCuNiZn nanocrystals to Vulcan XC-72R carbon black was 2:3). After centrifugation and vacuum drying, the mixture was heated to 200 °C at a heating rate of 5 °C / min and calcined in air for 2 h to obtain the Pd@PdPtCuNiZn / C catalyst supported on carbon black.

[0069] The crystallinity of the nanocrystals prepared in Example 1 and Comparative Examples 1-6 was tested using a Bruker X-ray powder diffractometer. Figure 1 The results show that the characteristic diffraction peaks of the nanocrystals prepared by Example 1 and Comparative Examples 1-6 are mainly located at 41.87°, 48.40°, 70.59° and 85.19°. Compared with the standard cards of elemental metals, the diffraction peaks of the multi-metal solid solution catalyst are mostly located between the diffraction peaks of elemental metals, which preliminarily illustrates the synthesis of alloy solid solutions and the effectiveness of the preparation method provided by the present invention. In addition, with the increase of the number of multi-element alloying elements, the characteristic diffraction peaks shift to higher angles. This lattice compression phenomenon is mainly attributed to the difference in atomic radii between noble metals (Pd and Pt) and other transition metal atoms (Co, Ni, Cu and Zn). With the introduction of transition metal atoms, the larger radius noble metal Pd and Pt atoms are replaced by smaller transition metal atoms in the lattice, resulting in a decrease in interplanar spacing.

[0070] Figure 2 Transmission electron microscopy reveals the morphological characteristics of the prepared Pd@PdPtCu nanocrystals, which are composed of...Figure 2 It can be seen that the nanocrystals exhibit an octahedral shape overall, with a size of approximately 20 nm; furthermore, with the increase of element types, from the ternary alloy Pd@PdPtCu ( Figure 2 ), quaternary alloy Pd@PdPtCuCo ( Figure 3 ), Pd@PdPtCuNi ( Figure 4 ), Pd@PdPtCuZn ( Figure 5 ), pentagonal alloy Pd@PdPtCuNiCo ( Figure 6 ), Pd@PdPtCuNiZn ( Figure 7 From hexa-element alloy Pd@PdPtCuNiCoZn ( Figure 8 The morphology of the core-shell nanocrystals remains unchanged, which also demonstrates the universality of the preparation method provided by this invention.

[0071] Depend on Figure 9 It can be seen that in the Pd@PdPtCuNiCoZn nanocrystals provided in Example 1 of the present invention, palladium is mainly distributed in the core part of the octahedron, while a small amount of palladium, as well as platinum, copper, zinc, cobalt and nickel are distributed in the shell part, proving the formation of Pd@PdPtCuNiCoZn multi-element alloy nanocrystals with Pd as the core.

[0072] Preparation method of OER test working electrode: 5 mg of the prepared catalyst was dispersed in 1 mL of mixed solution (490 μL ultrapure water, 490 μL isopropanol, 20 μL Nafion solution), and sonicated for 1 h to obtain 5 mg catalyst ·mL -1 The catalyst ink was prepared by carefully polishing the glassy carbon electrode (GCE) with Al2O3 polishing powder before dropping the catalyst ink onto the GCE (diameter: 4 mm, area: 0.1256 cm²). 2 The catalyst loading was 0.48 mg·cm³. -2 ).

[0073] Preparation method of ORR test working electrode: Take 15µL of the catalyst ink prepared by the above method and drop it onto the rotating disk electrode (RDE, diameter: 5mm, area: 0.19625cm²). 2 The catalyst loading was 0.38 mg·cm³. -2 Electrochemical tests were performed on the surface.

[0074] Figure 10 (a) and Figure 10 (b) It can be seen that the Pd@PdPtCu / C catalyst at 10 mA·cm -2The overpotential is 552 mV; with the introduction of transition metals Co, Ni and Zn, the Pd@PdPtCuCo / C catalyst (450 mV @ 10 mA·cm⁻¹) -2 ), Pd@PdPtCuNi / C(419mV@10mA·cm -2 ) and Pd@PdPtCuZn / C(479mV@10 mA·cm -2 The overpotentials of the Pd@PdPtCuNiCo / C catalyst decreased by 102 mV, 133 mV, and 73 mV, respectively; -2 ) and Pd@PdPtCuNiZn / C catalyst (374mV@10mA·cm -2 The overpotentials of the Pd@PdPtCuNiCoZn / C catalyst decreased by 140 mV and 178 mV, respectively; it is worth noting that the overpotentials of the Pd@PdPtCuNiCoZn / C catalyst (354 mV @ 10 mA·cm⁻¹) decreased by 140 mV and 178 mV, respectively. -2 The overpotential decreased by 198mV; Figure 10 (c) This demonstrates that the Pd@PdPtCuNiCoZn / C catalyst exhibits relatively fast reaction kinetics (with a minimum Tafel value of 66.44 mV·dec). -1 This greatly promotes the OER reaction; in addition, Figure 10 (d) It can be seen that the Pd@PdPtCuNiCoZn / C catalyst at 10 mA·cm -2 It operated stably for nearly 50 hours at a current density, which indicates that the catalyst prepared in Example 1 also has excellent stability.

[0075] The Zn-O2 battery employs a single electrolysis chamber design. The electrolyte is a mixed solution of 6M KOH and 0.2M Zn(CH3COO)2. The zinc sheet serves as the anode, and the carbon cloth supporting the catalyst serves as the cathode. The catalysts are the catalyst provided in Example 1 and a Pt / C+RuO2 catalyst, respectively, with a loading of 1 mg / cm³. 2 Electrochemical tests were performed on the catalyst using a CHI 760E electrochemical workstation (Shanghai Chenhua), yielding polarization and power density curves. Furthermore, the cycle stability of the Zn-O2 battery was obtained using a CT2001A (LAND) testing system, with the charge / discharge current density fixed at 10 mA·cm⁻¹. -2 Down.

[0076] Given that the cathode catalyst of a rechargeable aqueous Zn-O2 battery needs to possess dual functional properties in catalyzing both the oxygen reduction reaction and the hydrogen evolution reaction, the ORR performance of the catalysts prepared in Example 1 and Comparative Examples 1-6 in alkaline medium (0.1M KOH) was further evaluated; Figure 11 (a) and Figure 11As shown in (b), the Pd@PdPtCuNiCoZn / C catalyst exhibits excellent ORR activity, with a half-wave potential of 0.808 V, which is significantly better than that of the Pd@PdPtCu / C catalyst (0.750 V), Pd@PdPtCuCo / C catalyst (0.778 V), Pd@PdPtCuNi / C catalyst (0.790 V), and Pd@PdPtCuZn / C catalyst (0.760 V).

[0077] Figure 12 (a) The charge-discharge polarization curves and power density curves of an alkaline aqueous rechargeable Zn-O2 battery based on PdPtCuNiCoZn / C as the cathode catalyst are shown, with a peak power density of 91.64 mW·cm⁻¹. -2 It is superior to Pt / C (87.57 mW·cm⁻¹) -2 A Zn–O2 battery using Pd@PdPtCuNiCoZn / C catalyst as the cathode catalyst; in addition, a zinc-air battery using Pd@PdPtCuNiCoZn / C catalyst as the cathode at 10 mA·cm -2 Charge for 10 minutes, discharge for 10 minutes, charge again for 10 minutes, discharge for 10 minutes, and repeat this cycle continuously at a current density of 10 mA·cm⁻¹. -2 In constant current charge and discharge test ( Figure 12 (b) The battery loaded with the catalyst provided in Example 1 of this invention maintained a stable voltage plateau within 110 hours, confirming that the cathode loaded with Pd@PdPtCuNiCoZn / C catalyst has excellent cycle stability and meets the reliability requirements of practical applications.

[0078] The catalysts prepared in Examples 2 and 3 achieve similar effects to those in Example 1.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy, characterized in that, The Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy is a core-shell octahedral nanocrystal with Pd as the core and Pd, Pt, Cu, Ni, Co and Zn as the shells.

2. The Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy as described in claim 1, characterized in that, The Pd@PdPtCuNiCoZn octahedral nano-high entropy alloy comprises the following components in atomic percentage: Pd: 5%~35%, Pt: 5%~35%, Cu: 5%~35%, Ni: 5%~35%, Co: 5%~35%, and Zn: 5%~35%.

3. A method for preparing the Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy according to claim 1 or 2, characterized in that, Includes the following steps: S1. Dissolve the halide salt and polyvinylpyrrolidone in a first alcohol solvent to obtain a mixture; S2. Disperse palladium, platinum, copper, nickel, cobalt and zinc sources in the mixture, and then perform microwave treatment to obtain Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy.

4. The method for preparing Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy as described in claim 3, characterized in that, In S1, the ratio of polyvinylpyrrolidone to the first alcohol solvent is (200~250) mg: (25~35) mL; In S2, the mass ratio of the palladium source, platinum source, copper source, nickel source, cobalt source, zinc source, halide salt and polyvinylpyrrolidone is (17~20):(20~25):(10~15):(10~15):(10~15):(10~15):(400~500):(200~250).

5. The method for preparing Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy as described in claim 4, characterized in that, In S2, the mass ratio of the palladium source, platinum source, copper source, nickel source, cobalt source, zinc source, halide salt and polyvinylpyrrolidone is 17.73:20.49:13.45:12.96:12.98:13.63:476:

222.

6. The method for preparing Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy as described in claim 3, characterized in that, In S2, the power of the microwave processing is 600~800W; In S2, the microwave processing time is 60~240s.

7. A Pd@PdPtCuNiCoZn / C catalyst, characterized in that, Includes carbon black and the Pd@PdPtCuNiCoZn octahedral nano-high-entropy alloy of claim 1 or 2 supported on said carbon black.

8. The Pd@PdPtCuNiCoZn / C catalyst as described in claim 7, characterized in that, The mass ratio of the Pd@PdPtCuNiCoZn octahedral nano high-entropy alloy to carbon black is 2:(2.8~3.2).

9. A method for preparing the Pd@PdPtCuNiCoZn / C catalyst according to claim 7 or 8, characterized in that, Includes the following steps: The weighed carbon black and Pd@PdPtCuNiCoZn octahedral high-entropy nano-alloy were dispersed in a second alcohol solvent, and after solid-liquid separation, they were calcined to obtain the Pd@PdPtCuNiCoZn / C catalyst.

10. The application of the catalyst according to claim 7 or 8 in zinc-air batteries or electrocatalytic oxygen evolution reaction and oxygen reduction reaction.

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