General preparation method and application of ultra-small-size platinum-based low-medium-high-entropy alloy catalyst

Abstract

The invention discloses a general preparation method and application of an ultra-small and ultra-low loading platinum-based low-medium-high entropy alloy catalyst, and belongs to the technical field of catalyst preparation and electro-catalysis. The catalyst prepared by the method is uniform in size and uniform in dispersion, the process is simple and efficient, and various ultra-small platinum-based low-medium-high entropy alloy catalysts with different components, uniform size and adjustable crystallinity can be synthesized by simply changing reaction conditions. The catalyst shows excellent ORR catalytic performance on the rotating disc electrode and in the whole pH range.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and electrocatalysis technology, and particularly relates to a general preparation method and application of ultra-small and ultra-low loading platinum-based low-medium-high entropy alloy catalysts. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are promising sustainable energy systems that can efficiently convert chemical energy into electrical energy. The oxygen reduction reaction (ORR) at the cathode in a PEMFC is a process involving multiple electrons and protons, and its slow reaction kinetics limit its practical application. Currently, Pt-based catalysts remain the most promising catalysts for the ORR reaction under all pH conditions. However, the scarcity and high cost of Pt limit the large-scale application of fuel cells. Therefore, developing reasonable preparation methods, designing ultra-stable structures, and reducing Pt loading to improve the activity of Pt-based catalysts are of great significance for the practical application of fuel cells.

[0003] In recent years, research on platinum-based high-entropy alloys as efficient ORR catalysts has only just begun. Currently, many problems and challenges remain: Synthesis methods for high-entropy alloys, such as solvothermal methods, generally require the use of organic solvents, making the preparation process complex and cumbersome; while novel transient heating methods offer a simple and efficient process, they are typically carried out at temperatures above 1500℃, requiring specialized equipment and easily causing nanoparticles to fuse together, leading to uncontrollable aggregation, migration, and growth of the alloy, severely reducing its active surface area and resulting in unsatisfactory catalytic activity. Furthermore, the catalytic performance of high-entropy alloy catalysts needs improvement, especially its performance across the entire pH range. Therefore, designing a simple and efficient preparation process capable of mass-producing ultra-small platinum-based high-entropy alloy catalysts and achieving a highly efficient and stable ORR electrocatalytic process across the entire pH range is of great value and significance.

[0004] In view of this, the inventors developed a simple and efficient solvent-free ball milling method to successfully prepare a series of ultra-small, ultra-low loading platinum-based low-to-medium-to-high entropy alloy high-efficiency ORR catalysts across the entire pH range. This method primarily utilizes the interlayer confinement effect of inexpensive, acid- and alkali-resistant commercially available flake graphite carbon to encapsulate ultra-small high-entropy alloy clusters. The catalysts prepared by this method are uniform in size and dispersion, and the process is simple and efficient. By simply changing the reaction conditions, various ultra-small platinum-based low-to-medium-to-high entropy alloy catalysts with different compositions, uniform size, and tunable crystallinity can be synthesized. The catalysts exhibit excellent ORR catalytic performance on a rotating disk electrode and across the entire pH range. Summary of the Invention

[0005] To address the challenges of preparing Pt-based high-entropy alloy catalysts, including their large size and poor catalytic performance across the entire pH range, this invention leverages the interlayer confinement effect of inexpensive, acid- and alkali-resistant commercially available flake graphite carbon to effectively encapsulate ultra-small, low-platinum-loading high-entropy alloy nanoclusters. This invention cleverly selects oxygen-containing acetylacetone metal salts with relatively weak intermolecular bonding and first simply mixes them with commercially available flake graphite, then thoroughly grinds them. Finally, low-temperature heat treatment is used to in-situ pyrolyze the metal salt ions encapsulated within the carbon layers, forming uniformly sized and evenly distributed ultra-small platinum-based low-, medium-, and high-entropy alloy catalysts. Furthermore, the morphology and structure of the prepared materials were comprehensively characterized using XRD, TEM, and other analytical methods. In addition, the catalyst exhibits excellent electrocatalytic ORR activity and stability across the entire pH range in performance testing.

[0006] The first objective of this invention is to provide a low-to-medium-to-high entropy platinum-based alloy catalyst with ultra-small size and ultra-low platinum loading. This catalyst has good structural stability and activity, is resistant to strong oxidation, strong acids and strong bases, and has good catalytic performance for the reduction of oxygen to water across the entire pH range.

[0007] The second objective of this invention is to provide a general, batch preparation method for platinum-based low-to-medium-to-high entropy alloy catalysts with ultra-small size and ultra-low platinum loading.

[0008] The third objective of this invention is to provide an application of a platinum-based low-to-medium-to-high entropy alloy catalyst with ultra-small size and ultra-low platinum loading.

[0009] Technical solution

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] The preparation method of the ultra-small size, ultra-low loading platinum-based low-medium-high entropy alloy catalyst specifically includes the following steps:

[0012] S1. Simply mix the acetylacetonate precursors of various metals and the graphite precursor;

[0013] S2. Transfer the solid mixture of various metal acetylacetonate precursors and graphite precursors from step S1 into a ball mill jar.

[0014] S3. Start the ball mill equipment and set the working time;

[0015] S4. After thorough grinding, the solid mixture of various metal acetylacetone salt precursors and graphite precursors from step S3 is subjected to thermal annealing under a hydrogen / argon mixed atmosphere, and then cooled to room temperature to obtain the final catalyst product.

[0016] S5, electrochemical performance testing, and assembly into membrane electrode for application in fuel cells;

[0017] In addition, the method for preparing the platinum-based alloy catalyst according to the above-described embodiments of the present invention may also have the following additional technical features:

[0018] In step S1 of this invention, all metal salts used are platinum acetylacetonate precursors, such as iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, molybdenum acetylacetonate, and platinum acetylacetonate. The graphite precursors used are all commercially available flake graphite. It should be noted that the mass of the graphite precursor added is 2 to 10 times the total mass of the metal salts. Furthermore, the mixing method can be any of the following combinations: single platinum metal salt and flake graphite; binary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, molybdenum platinum and flake graphite; ternary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, nickel platinum and flake graphite (low-entropy alloy catalysts); quaternary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, molybdenum platinum and flake graphite (medium-entropy alloy catalysts); pentagonal metal salt, such as iron platinum, cobalt platinum, nickel platinum (high-entropy alloy catalysts) and flake graphite.

[0019] In step S2 of this invention, the ball milling equipment used is a high-speed vibrating ball mill.

[0020] In step S3 of the present invention, the mechanical grinding process can be carried out for 1-8 hours;

[0021] In step S4 of this invention, the specific gas used is a 5% hydrogen / argon mixture; the heating rate can be 1 to 10 °C / min, the holding temperature can be 300 to 800 °C, and the holding time can be 0.5 to 5 hours.

[0022] In step S5 of this invention, electrochemical performance testing is performed using a glassy carbon electrode further prepared with the catalyst obtained in step S5 as the working electrode and a carbon rod as the counter electrode. Electrolyte solutions are prepared sequentially in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, using 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range is 0–1.2 V (relative to the standard hydrogen electrode), the scan rate is 10 mV / s, and the rotation speed is 1600 rpm.

[0023] Furthermore, the present invention also provides the application of the catalyst in electrocatalytic oxygen reduction reactions across the entire pH range.

[0024] Beneficial effects

[0025] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0026] 1. From a preparation process perspective: This method utilizes high-energy mechanical grinding to break the intermolecular bonds of the metal precursor, allowing the metal salt to be effectively encapsulated and confined within the two-dimensional carbon support layer. This innovative dispersion method effectively solves the problems of metal precipitation and elemental segregation in traditional preparation processes. Subsequent low-temperature solid-state thermal annealing yields platinum alloy catalysts with uniform gram-scale distribution and ultra-small size. This process features low metal loss, high yield, high dispersion, high metal loading, and low precious metal loading. Furthermore, the synthesis process is simple, stable, environmentally friendly, and safe (requiring no solvents), with few steps (only two steps), making it highly versatile and suitable for large-scale production, with significant application potential.

[0027] 2. From a design innovation perspective: During the mechanical grinding and dispersion process, the weak bonding interactions between acetylacetone metal salts effectively confine metal ions within the two-dimensional carbon layer structure of the support, ensuring uniform dispersion on the support. This effectively solves the problems of metal sedimentation and elemental segregation, and avoids nanocrystal aggregation during high-temperature processing, achieving a high dispersion effect. Furthermore, due to the strong interactions between metals, the introduced metal is more easily incorporated into the Pt crystal lattice structure, preventing the metal from forming a separate phase. During sintering, controlling the heating / cooling rate allows reduction within a narrow, lower temperature range, improving metal dispersibility. The rapid cooling process generates lattice mismatch stress within the catalyst, exposing more active sites and enhancing catalyst activity. The high metal dispersibility maximizes metal loading, reducing potential application costs in fuel cells. This can be achieved by reducing catalyst layer thickness, improving mass transfer efficiency, further reducing metal usage, and lowering catalyst costs.

[0028] 3. From the perspective of catalytic innovation: This method designs and prepares an ultra-small high-entropy alloy catalyst. Due to its variable composition space and unique multi-element mixed structure, it can simultaneously achieve the design goals of high activity (composition design), high stability (high-entropy stability) and low cost (non-precious metal substitute). It achieves high ORR catalytic performance in a complex full pH range and has broad prospects for commercial application. Attached Figure Description

[0029] Figure 1 These are transmission electron microscope (TEM) images (scale bar: 20 nm) and particle size distribution diagrams (internal insets) of the catalysts obtained in Examples 1, 2, 3, 4, 5, and 6 of this invention.

[0030] Figure 2 These are X-ray diffraction patterns of the catalysts obtained in Examples 1, 2, 3, 4, 5, and 6 of this invention.

[0031] Figure 3 These are X-ray diffraction patterns of the catalysts obtained in Examples 6, 7, 8, 9, 10, and 11 of this invention.

[0032] Figure 4 These are electrochemical performance test graphs of the catalysts obtained in Examples 6, 7, 8, 9, 10, and 11 of this invention (a: cyclic voltammetry curves under oxygen and argon saturation; b: polarization curves; c: Tafel slope; d: main ORR performance parameters).

[0033] Figure 5 These are electrochemical performance test diagrams of the catalysts obtained in Examples 1, 2, 3, 4, 5, and 6 of this invention in different media (a, b: acidic media; c, d: neutral media; e, f: alkaline media). Figure 6 These are important performance parameters of the catalysts obtained in embodiments 1, 2, 3, 4, 5, and 6 of this invention in different media, along with corresponding cycle stability test diagrams (a, b: acidic media; c, d: neutral media; e, f: alkaline media). Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Example 1:

[0036] Example 1 of this invention provides a method for preparing a monocomponent ultrasmall platinum-based catalyst, comprising the following steps:

[0037] The specific experimental steps are as follows:

[0038] S1. Accurately weigh 589.0 mg of platinum acetylacetone;

[0039] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0040] S3. Simply mix the two reactants weighed in steps S1 and S2 above.

[0041] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0042] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: OP@C-600;

[0043] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0044] Example 2:

[0045] Example 2 of this invention provides a method for preparing a binary ultrasmall platinum-based catalyst. Based on Example 1, the metal salts are changed to corresponding platinum and iron salts; the experimental case implemented is referred to as Example 2.

[0046] The specific experimental steps are as follows:

[0047] S1. Accurately weigh 294.8 mg of platinum acetylacetone and 264.8 mg of iron acetylacetone;

[0048] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0049] S3. Weigh the two reactants from steps S1 and S2 and mix them simply.

[0050] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0051] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PF@C-600;

[0052] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0053] Example 3:

[0054] Example 3 of this invention provides a method for preparing a binary ultrasmall platinum-based catalyst. Based on Example 1, the metal salts are changed to corresponding platinum and cobalt salts; the experimental case implemented is referred to as Example 3.

[0055] The specific experimental steps are as follows:

[0056] S1. Accurately weigh 294.8 mg of platinum acetylacetone and 264.8 mg of cobalt acetylacetone;

[0057] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0058] S3. Simply mix the two reactants weighed in steps S1 and S2 above.

[0059] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0060] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PC@C-600;

[0061] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0062] Example 4:

[0063] Example 4 of this invention provides a method for preparing a binary ultrasmall platinum-based catalyst. Based on Example 1, the metal salts are changed to corresponding platinum and nickel salts; the experimental case implemented is referred to as Example 4.

[0064] The specific experimental steps are as follows:

[0065] S1. Accurately weigh 294.8 mg of platinum acetylacetone and 192.8 mg of nickel acetylacetone;

[0066] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0067] S3. Simply mix the two reactants weighed in steps S1 and S2 above.

[0068] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0069] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PN@C-600;

[0070] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0071] Example 5:

[0072] Example 5 of this invention provides a method for preparing a binary ultrasmall platinum-based catalyst. Based on Example 1, the metal salts are changed to corresponding platinum and molybdenum salts; the experimental case implemented is referred to as Example 5.

[0073] The specific experimental steps are as follows:

[0074] S1. Accurately weigh 294.8 mg of platinum acetylacetone and 244.7 mg of molybdenum acetylacetone;

[0075] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0076] S3. Simply mix the two reactants weighed in steps S1 and S2 above.

[0077] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0078] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PM@C-600;

[0079] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0080] Example 6:

[0081] Example 6 of this invention provides a method for preparing a pentagonal ultra-small platinum-based high-entropy alloy catalyst. Based on Example 1, the metal salts are changed to corresponding platinum, iron, cobalt, nickel, and molybdenum salts. The experimental case implemented is referred to as Example 6. The specific experimental steps are as follows:

[0082] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0083] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0084] S3. Weigh all reactants from steps S1 and S2 and mix them simply.

[0085] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 600℃, and the holding time to 3 hours.

[0086] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-600;

[0087] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0088] Example 7:

[0089] Example 7 of this invention provides a method for preparing a five-element ultra-small platinum-based catalyst. Based on Example 6, the reduction temperature is lowered to 300°C, and the resulting sample is referred to as Example 7 sample.

[0090] The specific experimental steps are as follows:

[0091] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0092] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0093] S3. Weigh all the medicines from steps S1 and S2 above and mix them simply.

[0094] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 300℃, and the holding time to 3 hours.

[0095] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-300;

[0096] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0097] Example 8:

[0098] Example 8 of this invention provides a method for preparing a five-membered ultrasmall platinum-based catalyst. Based on Example 6, the reduction temperature was lowered to 400℃, and the resulting sample is designated as Example 8 sample.

[0099] The specific experimental steps are as follows:

[0100] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0101] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0102] S3. Weigh all the medicines from steps S1 and S2 above and mix them simply.

[0103] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 400℃, and the holding time to 3 hours.

[0104] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-400;

[0105] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0106] Example 9:

[0107] Example 9 of this invention provides a method for preparing a five-membered ultrasmall platinum-based catalyst. Based on Example 6, the reduction temperature was lowered to 500℃, and the resulting sample is referred to as Example 9 sample.

[0108] The specific experimental steps are as follows:

[0109] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0110] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0111] S3. Weigh all the medicines from steps S1 and S2 above and mix them simply.

[0112] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 500℃, and the holding time to 3 hours.

[0113] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-500;

[0114] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0115] Example 10:

[0116] Example 10 of this invention provides a method for preparing a five-component ultrasmall platinum-based catalyst. Based on Example 6, the reduction temperature was increased to 700°C, and the resulting sample is designated as Example 10 sample.

[0117] The specific experimental steps are as follows:

[0118] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0119] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0120] S3. Weigh all the medicines from steps S1 and S2 above and mix them simply.

[0121] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 700℃, and the holding time to 3 hours.

[0122] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-700;

[0123] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

[0124] Example 11:

[0125] Example 11 of this invention provides a method for preparing a five-element ultrasmall platinum-based catalyst. Based on Example 6, the reduction temperature was increased to 800°C, and the resulting sample is designated as Example 11 sample.

[0126] Includes the following steps:

[0127] The specific experimental steps are as follows:

[0128] S1. Accurately weigh 118.0 mg platinum acetylacetone, 106.0 mg iron acetylacetone, 107.0 mg cobalt acetylacetone, 77.0 mg nickel acetylacetone, and 98.0 mg molybdenum acetylacetone;

[0129] S2. Accurately weigh 1.20g of commercial flake graphite (10,000 mesh);

[0130] S3. Weigh all the medicines from steps S1 and S2 above and mix them simply.

[0131] S4. Transfer the solid mixture obtained in step S3 to a ball mill jar and place it in the equipment; set the ball milling time to 6 hours; the heating rate to 3℃ / min, the holding temperature to 800℃, and the holding time to 3 hours.

[0132] S5. After heat treatment, the final product catalyst is obtained after cooling, denoted as: O-PFCNM@C-800;

[0133] S6. Electrochemical Performance Testing: Using the glassy carbon electrode prepared with the catalyst obtained in S5 above as the working electrode and the carbon rod as the counter electrode, performance tests were conducted in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, with 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range was 0–1.2 V (relative to the standard hydrogen electrode), the scan rate was 10 mV / s, and the rotation speed was 1600 rpm.

Claims

1. A general preparation method and application of ultra-small and ultra-low loading platinum-based low-medium-high entropy alloy catalysts, comprising the following steps: S1. Simply mix the acetylacetonate precursors of various metals and the graphite precursor; S2. Transfer the solid mixture of various metal acetylacetonate precursors and graphite precursors from step S1 into a ball mill jar. S3. Start the ball mill equipment and set the working time; S4. After thorough grinding, the solid mixture of various metal acetylacetone salt precursors and graphite precursors from step S3 is subjected to thermal annealing under a hydrogen / argon mixed atmosphere, and then cooled to room temperature to obtain the final catalyst product. S5, electrochemical performance testing, and assembly into membrane electrode for application in fuel cells; In addition, the method for preparing the platinum-based alloy catalyst according to the above-described embodiments of the present invention may also have the following additional technical features: In step S1 of this invention, all metal salts used are platinum acetylacetonate precursors, such as iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, molybdenum acetylacetonate, and platinum acetylacetonate. The graphite precursors used are all commercially available flake graphite. It should be noted that the mass of the graphite precursor added is 2 to 10 times the total mass of the metal salts. Furthermore, the mixing method can be any of the following combinations: single platinum metal salt and flake graphite; binary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, molybdenum platinum and flake graphite; ternary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, nickel platinum and flake graphite (low-entropy alloy catalysts); quaternary metal salt and flake graphite, such as iron platinum, cobalt platinum, nickel platinum, molybdenum platinum and flake graphite (medium-entropy alloy catalysts); pentagonal metal salt, such as iron platinum, cobalt platinum, nickel platinum (high-entropy alloy catalysts) and flake graphite. In step S2 of this invention, the ball milling equipment used is a high-speed vibrating ball mill. In step S3 of the present invention, the mechanical grinding process can be carried out for 1-8 hours; In step S4 of this invention, the specific gas used is a 5% hydrogen / argon mixture; the heating rate can be 1 to 10 °C / min, the holding temperature can be 300 to 800 °C, and the holding time can be 0.5 to 5 hours. In step S5 of this invention, electrochemical performance testing is performed using a glassy carbon electrode further prepared with the catalyst obtained in step S5 as the working electrode and a carbon rod as the counter electrode. Electrolyte solutions are prepared sequentially in acidic (silver / silver chloride electrode as reference electrode), neutral (silver / silver chloride electrode as reference electrode), and alkaline (mercury / mercury oxide electrode as reference electrode) media, using 0.1 mol / L perchloric acid (acidic), phosphate buffer (neutral), and potassium hydroxide (alkaline) aqueous solutions saturated with nitrogen and oxygen, respectively. The oxygen reduction linear scan range is 0–1.2 V (relative to the standard hydrogen electrode), the scan rate is 10 mV / s, and the rotation speed is 1600 rpm.

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