Carbon matrix composite material and method for producing and using same

Abstract

The application belongs to the technical field of electrocatalytic oxygen reduction, and particularly relates to a carbon-based composite material and a preparation method and application thereof. In the application, since the transition metal oxide serves as an intermediate structure, direct contact of platinum-based intermetallic compounds and the carbon-based matrix is avoided, and corrosion and damage effects of the platinum-based intermetallic compounds on the carbon-based matrix in an electrocatalytic process (such as a fuel cell) are fundamentally eliminated, thereby significantly improving long-term stability of the catalyst in an electrocatalytic reaction. In addition, based on interaction between the intermetallic compounds and the matrix, the activity and selectivity of the platinum-based intermetallic compounds can be simply regulated by changing the type of the oxide. Finally, construction of the intermetallic compounds can greatly reduce the platinum usage and optimize the cost. In view of the platinum-based intermetallic compound / transition metal oxide / carbon-based matrix series structure features obtained by the application, more excellent performance and effects will be exhibited in the fields of hydrogen-oxygen fuel cells or zinc-air batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic oxygen reduction technology, specifically relating to a carbon-based composite material, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are power generation devices that directly convert chemical energy into electrical energy. They feature low-temperature start-up, high power density, high energy conversion efficiency, and environmental friendliness, making them promising for widespread application in transportation, aerospace, portable or stationary power generation. However, high cost and short lifespan are the two major bottlenecks hindering their commercialization. Compared to cost, the short lifespan of PEMFCs is a more critical issue that urgently needs to be addressed, directly impacting whether this technology can achieve large-scale industrial application. As the core component of fuel cells, the catalyst's performance directly determines the overall efficiency of the fuel cell. Current research generally indicates that catalyst nanoparticle growth and carbon support structure destruction are the two main causes of catalyst deactivation, and these two failure mechanisms are coupled and synergistic during actual battery operation, accelerating the degradation of battery performance.

[0003] Among numerous catalyst systems, Pt / C catalysts have become the most widely used materials in commercial applications due to their excellent catalytic activity. However, due to the harsh working environment within PEMFCs (strong acidity, high potential, high humidity, and high temperature, etc.), Pt / C catalysts experience Pt particle dissolution, migration, and aggregation over time, or the interaction between Pt and the support weakens, resulting in a decrease in the electrochemical active surface area (ECSA) and catalyst performance degradation, leading to unsatisfactory PEMFC battery life. The main reasons for the reduction in ECSA of Pt / C catalysts can be summarized as follows: ① migration and aggregation of nano-sized Pt particles on the carbon support; ② dissolution and redeposition of Pt nanoparticles due to electrochemical Ostwald ripening; ③ Pt poisoning; ④ corrosion of the carbon support, leading to Pt detachment and aggregation.

[0004] Due to the weak interaction between Pt and the carbon support, nanoscale Pt particles are prone to growth, migration, and dissolution during battery operation, resulting in the loss of catalyst active sites and membrane poisoning. Furthermore, the presence of Pt nanoparticles accelerates carbon oxidation and corrosion due to the "backflow" of adsorbed oxygen-containing functional groups to the metal particle surface, causing Pt to detach from or aggregate on the electrode, and in severe cases, even catalyst collapse. It is noteworthy that while the carbon support used in PEMFCs needs to possess characteristics such as high specific surface area, good thermal stability, excellent electrochemical stability, high conductivity, and strong corrosion resistance, the large number of surface defects and unsaturated bonds resulting from the high specific surface area can trigger carbon oxidation reactions in the cathode environment. In the PEMFC cathode, thermodynamically, carbon oxidation reactions generate oxygen-containing functional groups such as -OH, -COOH, and -C=O. CO and CO-like products stably adsorb onto the surface of the Pt catalyst, causing Pt poisoning. Therefore, it is essential to improve the stability of the Pt / C system. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon-based composite material, its preparation method, and its application. The carbon-based composite material provided by this invention has high catalytic stability as a catalyst for electrocatalytic oxygen reduction.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a carbon matrix composite material, comprising a carbon matrix and a modified transition metal oxide supported on the carbon matrix; The modified transition metal oxide includes a transition metal oxide and a platinum-based intermetallic compound supported on the transition metal oxide.

[0007] Preferably, the transition metal oxide includes at least one of tantalum oxide, zirconium oxide, hafnium oxide, and niobium oxide; The carbon matrix includes at least one of conductive carbon black, graphene, and carbon nanotubes. The mass percentage of transition metal oxidation in the carbon matrix composite material is 10-30%.

[0008] Preferably, the platinum-based intermetallic compound comprises platinum and an auxiliary metal; the auxiliary metal comprises at least one selected from iron, cobalt, and nickel. The molar ratio of platinum to auxiliary metal in the platinum-based intermetallic compound is 1:1 or 3:1; The platinum-based intermetallic compound has a loading percentage of 30-60% in the carbon matrix composite material.

[0009] The present invention also provides a method for preparing the carbon matrix composite material described in the above technical solution, comprising the following steps: A first mixture is obtained by first mixing a transition metal source, a carbon matrix, and an organic solvent, and then removing the organic solvent. The first mixture was sulfided in a sulfur-containing atmosphere to obtain a sulfided product; The sulfide product, platinum source, and organic solvent are mixed in a second mixture, and after removing the organic solvent, a second mixture is obtained. The second mixture was subjected to a first reduction and oxidation in sequence to obtain an oxidation product; The oxidation product, auxiliary metal source, and water are mixed in a third step. After removing the water, the resulting product is subjected to a second reduction to obtain the carbon matrix composite material.

[0010] Preferably, the transition metal source includes at least one of tantalum source, zirconium source, hafnium source and niobium source; The tantalum source includes at least one of tantalum ethoxide, tantalum n-butoxide, and tantalum chloride. The zirconium source includes at least one of zirconium ethoxide, zirconium n-butoxide, and zirconium chloride; The hafnium source includes at least one of ethanol hafnium, n-butanol hafnium, and hafnium chloride; The niobium source includes at least one of niobium ethanol, niobium n-butoxide, and niobium chloride.

[0011] Preferably, the sulfur-containing atmosphere includes a mixed atmosphere of hydrogen sulfide and argon or carbon disulfide with argon as the carrier gas. The volume ratio of argon to hydrogen sulfide in the mixed atmosphere is 95:5 to 75:25. The flow rate of carbon disulfide using argon as the carrier gas is 0.1~0.3 L / min; The vulcanization temperature is 300~400℃, the heating rate is 3~10℃ / min, and the holding time is 2~5h.

[0012] Preferably, the platinum source includes chloroplatinic acid hexahydrate; The mass ratio of the sulfide product to the platinum source is 0.5~1:1; The first reduction is carried out in a hydrogen-containing atmosphere, which includes a mixture of argon and hydrogen, wherein the volume ratio of argon to hydrogen in the mixture is 95:5; and the flow rate of the hydrogen-containing atmosphere is 0.2~0.3 L / min. The temperature of the first reduction is 250~300℃, the heating rate is 5~10℃ / min, and the holding time is 1~3h.

[0013] Preferably, the oxidation is carried out in an air atmosphere, the oxidation temperature is 280~300℃, the heating rate is 5~10℃ / min, and the holding time is 2~6h.

[0014] Preferably, the auxiliary metal source includes at least one of an iron source, a cobalt source, and a nickel source; The iron source includes at least one of ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric acetate, ferric acetylacetone, and ferric citrate; the cobalt source includes at least one of cobalt chloride hexahydrate, anhydrous cobalt chloride, cobalt nitrate hexahydrate, cobalt acetylacetone, cobalt sulfate, dicobalt ethylenediaminetetraacetate, and hexaamminecobalt trichloride; the nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel hydroxide, and nickel acetylacetone. The second reduction is carried out in a hydrogen-containing atmosphere, which includes a mixture of argon and hydrogen, wherein the volume ratio of argon to hydrogen in the mixture is 95:5; and the flow rate of the hydrogen-containing atmosphere is 0.3~0.8 L / min. The second reduction temperature is 900~1000℃, the heating rate is 5~20℃ / min, and the holding time is 1~4h; After the second reduction, the product is further cooled to room temperature; the cooling rate is 5~10℃ / min.

[0015] The present invention also provides the application of the carbon-based composite material described in the above technical solution or the composite material prepared by the preparation method described in the above technical solution as a catalyst in electrocatalytic oxygen reduction.

[0016] Compared with the prior art, the beneficial effects of the present invention include: In this invention, the transition metal oxide serves as an intermediate structure, avoiding direct contact between the platinum-based intermetallic compound and the carbon matrix. This fundamentally eliminates the corrosive and destructive effects of the platinum-based intermetallic compound on the carbon matrix during electrocatalysis (such as in fuel cells), thereby significantly improving the long-term stability of the catalyst in electrocatalytic reactions. Furthermore, based on the interaction between the intermetallic compound and the matrix, the activity and selectivity of the platinum-based intermetallic compound can be easily controlled by changing the type of oxide. Finally, the construction of the intermetallic compound can greatly reduce the amount of platinum used, optimizing costs. Given the tandem structure of the platinum-based intermetallic compound / transition metal oxide / carbon matrix obtained in this invention, it will exhibit superior performance and effects in fields such as hydrogen-oxygen fuel cells or zinc-air batteries.

[0017] The present invention also provides a method for preparing the carbon matrix composite material described in the above technical solution.

[0018] In this invention, transition metal oxide nanoparticles are first deposited on a carbon matrix via hydrolysis, and then transformed into a transition metal sulfide@oxide core-shell structure through sulfidation. Subsequently, platinum components are introduced by calcination under a reducing atmosphere using an impregnation method. The key steps are low-temperature air oxidation and subsequent high-temperature hydrogen reduction of the resulting material. This process utilizes the strong interaction between platinum and sulfur to selectively anchor platinum and corresponding metal ions on the sulfide surface, ultimately forming a tandem structure. This unique "sulfidation-oxidation-reduction" process not only achieves site-specific loading of platinum-based intermetallic compounds on the sulfide but also effectively suppresses particle sintering during the high-temperature reduction process, thereby successfully obtaining small-sized, highly dispersed platinum-based intermetallic compound nanoparticles. This invention, through a unique metal oxide "sulfidation-oxidation-reduction" process, successfully constructs a platinum-based intermetallic compound / transition metal oxide / carbon matrix tandem structure, further improving the stability of the catalyst. Attached Figure Description

[0019] Figure 1 Transmission electron microscopy (TEM) image of the carbon matrix composite material prepared in Example 1; Figure 2 Transmission electron microscopy (TEM) image of the carbon matrix composite material prepared in Example 2; Figure 3 Transmission electron microscopy (TEM) image of the carbon matrix composite material prepared in Example 3; Figure 4 The image shown is a transmission electron microscope (TEM) image of the carbon matrix composite material prepared in Example 4. Detailed Implementation

[0020] This invention provides a carbon matrix composite material, comprising a carbon matrix and a modified transition metal oxide supported on the carbon matrix; The modified transition metal oxide includes a transition metal oxide and a platinum-based intermetallic compound supported on the transition metal oxide.

[0021] In this invention, the transition metal oxide preferably includes at least one selected from tantalum oxide, zirconium oxide, hafnium oxide, and niobium oxide. In this invention, the carbon matrix preferably includes at least one selected from conductive carbon black, graphene, and carbon nanotubes; the conductive carbon black is preferably of the following types: Ketjenblack EC-600JD, Ketjenblack EC-300J, Blackpearls 2000, or Vulcan XC-72R. In this invention, the mass percentage of transition metal oxide in the carbon matrix composite material is preferably 10-30%, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%.

[0022] In this invention, the platinum-based intermetallic compound preferably includes platinum and an auxiliary metal; the auxiliary metal preferably includes at least one of iron, cobalt, and nickel; the molar ratio of platinum to the auxiliary metal in the platinum-based intermetallic compound is preferably 1:1 or 3:1; the loading mass percentage of the platinum-based intermetallic compound in the carbon matrix composite material is preferably 30-60%, specifically 30%, 35%, 40%, 45%, 50%, 55%, or 60%.

[0023] The present invention also provides a method for preparing the carbon matrix composite material described in the above technical solution, comprising the following steps: A first mixture is obtained by first mixing a transition metal source, a carbon matrix, and an organic solvent, and then removing the organic solvent. The first mixture was sulfided in a sulfur-containing atmosphere to obtain a sulfided product; The sulfide product, platinum source, and organic solvent are mixed in a second mixture, and after removing the organic solvent, a second mixture is obtained. The second mixture was subjected to a first reduction and oxidation in sequence to obtain an oxidation product; The oxidation product, auxiliary metal source, and water are mixed in a third step. After removing the water, the resulting product is subjected to a second reduction to obtain the carbon matrix composite material.

[0024] In this invention, a transition metal source, a carbon matrix, and an organic solvent are first mixed, and after removing the organic solvent, a first mixture is obtained.

[0025] In this invention, the transition metal source preferably includes at least one selected from tantalum, zirconium, hafnium, and niobium; the tantalum source preferably includes at least one selected from tantalum ethoxide, tantalum n-butoxide, and tantalum chloride; the zirconium source preferably includes at least one selected from zirconium ethoxide, zirconium n-butoxide, and zirconium chloride; the hafnium source preferably includes at least one selected from hafnium ethoxide, hafnium n-butoxide, and hafnium chloride; and the niobium source preferably includes at least one selected from niobium ethoxide, niobium n-butoxide, and niobium chloride. In this invention, the organic solvent preferably includes ethanol. This invention does not impose a special limitation on the amount of the organic solvent used, as long as the components are uniformly dispersed.

[0026] In this invention, the first mixing process preferably includes: ultrasonically dispersing a carbon matrix in an organic solvent, and adding a transition metal source and stirring until homogeneous. In this invention, the removal of the organic solvent is preferably achieved by rotary evaporation. In this invention, the first mixture is preferably a carbon matrix and a transition metal oxide supported on the carbon matrix.

[0027] After obtaining the first mixture, the present invention sulfides the first mixture in a sulfur-containing atmosphere to obtain a sulfide product.

[0028] In this invention, the sulfur-containing atmosphere preferably includes a mixed atmosphere of hydrogen sulfide and argon or carbon disulfide with argon as the carrier gas; the volume ratio of argon to hydrogen sulfide in the mixed atmosphere is preferably 95:5 to 75:25; the flow rate of carbon disulfide with argon as the carrier gas is preferably 0.1 to 0.3 L / min, specifically 0.1 L / min, 0.2 L / min, or 0.3 L / min. In this invention, the vulcanization temperature is preferably 300~400℃, specifically 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃; the heating rate is preferably 3~10℃ / min, specifically 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min; and the holding time is preferably 2~5h, specifically 2h, 3h, 4h, or 5h. In this invention, the vulcanization product is preferably a carbon matrix and a transition metal sulfide / transition metal oxide composite product supported on the carbon matrix.

[0029] After obtaining the sulfidation product, the present invention mixes the sulfidation product, platinum source and organic solvent in a second mixture, and removes the organic solvent to obtain a second mixture.

[0030] In this invention, the platinum source preferably includes chloroplatinic acid hexahydrate; the mass ratio of the sulfide product to the platinum source is preferably 0.5~1:1; the organic solvent preferably includes ethanol. This invention does not have a specific limitation on the amount of the organic solvent used, as long as it ensures uniform dispersion of all raw materials. In this invention, the second mixing process is preferably: dispersing the sulfide product in an organic solvent, and then adding the platinum source and mixing evenly. In this invention, the organic solvent is preferably removed by rotary evaporation. In this invention, the second mixture is preferably a carbon matrix and a platinum oxide / transition metal sulfide / transition metal oxide composite product supported on the carbon matrix.

[0031] After obtaining the second mixture, the present invention performs a first reduction and oxidation on the second mixture in sequence to obtain an oxidation product.

[0032] In this invention, the first reduction is preferably carried out in a hydrogen-containing atmosphere, which preferably includes a mixture of argon and hydrogen, with a volume ratio of argon to hydrogen of 95:5; the flow rate of the hydrogen-containing atmosphere is preferably 0.2~0.3 L / min. In this invention, the temperature of the first reduction is preferably 250~300℃, specifically 250℃, 260℃, 270℃, 280℃, 290℃, or 300℃; the heating rate is preferably 5~10℃ / min, specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min; the holding time is preferably 1~3h, specifically 1h, 2h, or 3h. In this invention, the reduction product obtained after reduction is preferably a carbon matrix and a platinum / transition metal sulfide / transition metal oxide composite product supported on the carbon matrix.

[0033] In this invention, the oxidation is preferably carried out in an air atmosphere, and the oxidation temperature is preferably 280~300℃, specifically 280℃, 290℃, or 300℃; the heating rate is preferably 5~10℃ / min, specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min; the holding time is preferably 2~6h, specifically 2h, 3h, 4h, 5h, or 6h. In this invention, the oxidation product is preferably a carbon matrix and a platinum oxide / transition metal oxide composite product supported on the carbon matrix.

[0034] After obtaining the oxidation product, the present invention mixes the oxidation product, auxiliary metal source and water in a third mixture, removes the water, and then performs a second reduction on the obtained product to obtain the carbon matrix composite material.

[0035] In this invention, the auxiliary metal source preferably includes at least one of an iron source, a cobalt source, and a nickel source; the iron source preferably includes at least one of ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric acetate, ferric acetylacetonate, and ferric citrate; the cobalt source preferably includes at least one of cobalt chloride hexahydrate, anhydrous cobalt chloride, cobalt nitrate hexahydrate, cobalt acetylacetonate, cobalt sulfate, dicobalt ethylenediaminetetraacetate, and hexaamminecobalt trichloride; the nickel source preferably includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel hydroxide, and nickel acetylacetonate. In this invention, the water is preferably deionized water. This invention does not have a specific limitation on the amount of water used, as long as it ensures uniform dispersion of the raw materials. In this invention, the third mixing process is preferably: dispersing the oxidation product in water, and then adding the cobalt source and mixing evenly. In this invention, the method of removing water is preferably rotary evaporation.

[0036] In this invention, the second reduction is preferably carried out in a hydrogen-containing atmosphere, which preferably includes a mixture of argon and hydrogen, wherein the volume ratio of argon to hydrogen in the mixture is preferably 95:5; the flow rate of the hydrogen-containing atmosphere is preferably 0.3~0.8 L / min, specifically 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, or 0.8 L / min; the temperature of the second reduction is preferably 900~1000℃, specifically 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃, or 1000℃; and the heating rate is preferably 5~20℃ / min. Specifically, the temperature / min can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min, 16℃ / min, 17℃ / min, 18℃ / min, 19℃ / min, or 20℃ / min; the holding time is preferably 1~4h, specifically 1h, 2h, 3h, or 4h; after the second reduction, it is also preferable to cool the obtained product to room temperature; the cooling rate is preferably 5~10℃ / min, specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min.

[0037] The present invention also provides the application of the carbon-based composite material described in the above technical solution or the composite material prepared by the preparation method described in the above technical solution as a catalyst in electrocatalytic oxygen reduction.

[0038] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 100 mg of Ketjenblack EC-600JD was uniformly ultrasonically dispersed in 50 mL of ethanol, and then 46 mg of tantalum ethoxide was added and stirred until homogeneous. The ethanol was removed by rotary evaporation to obtain the first mixture (tantalum oxide / carbon matrix). The first mixture obtained above was placed in a crucible, and then a mixture of argon and hydrogen sulfide (volume ratio of 95:5) was introduced at a flow rate of 0.1 L / min and sulfided at 300 °C for 2 h with a heating rate of 3 °C / min to obtain the sulfided product (tantalum sulfide@tantalum oxide / carbon matrix). The sulfide product obtained above was dispersed in ethanol, 102 mg of chloroplatinic acid hexahydrate was added, and after rotary evaporation to dryness, a second mixture (platinum oxide / tantalum sulfide@tantalum oxide / carbon matrix) was obtained. The second mixture obtained above was reduced for 1 h at 250 °C under a mixed atmosphere of argon and hydrogen (volume ratio of 95:5, flow rate of 0.2 L / min) and a heating rate of 5 °C / min to obtain the reduction product (platinum / tantalum sulfide@tantalum oxide / carbon matrix). Next, air was introduced, and oxidation was carried out at 300℃ for 4 hours with a heating rate of 5℃ / min to obtain the oxidation product (platinum oxide@tantalum oxide / carbon matrix). The oxidation product obtained above was dispersed in deionized water, and 47 mg of cobalt chloride hexahydrate was added. After rotary evaporation to dryness, the resulting powder was heated to 900 °C at a heating rate of 5 °C / min and held at that temperature for 2 h. Then, it was cooled to room temperature at a rate of 5 °C / min to finally obtain a composite material with a tandem structure (platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to cobalt in the platinum-cobalt intermetallic compound is 1:1, the mass percentage of tantalum oxide is 14%, and the mass percentage of the platinum-cobalt intermetallic compound is 30%).

[0041] Example 2 100 mg of Ketjenblack EC-600JD was uniformly ultrasonically dispersed in 50 mL of ethanol, and then 46 mg of tantalum ethoxide was added and stirred until homogeneous. The ethanol was removed by rotary evaporation to obtain the first mixture (tantalum oxide / carbon matrix). The first mixture obtained above was placed in a crucible, and then a mixture of argon and hydrogen sulfide gas (volume ratio of 95:5) was introduced at a flow rate of 0.2 L / min and sulfided at 400 °C for 2 h with a heating rate of 5 °C / min to obtain the sulfided product (tantalum sulfide@tantalum oxide / carbon matrix). The sulfide product obtained above was dispersed in ethanol, and 120.6 mg of chloroplatinic acid hexahydrate was added. After rotary evaporation to dryness, a second mixture (platinum oxide / tantalum sulfide@tantalum oxide / carbon matrix) was obtained. The second mixture obtained above was reduced for 2 hours at 300°C under a mixed atmosphere of argon and hydrogen (volume ratio of 95:5, flow rate of 0.2 L / min) and a heating rate of 5°C / min to obtain the reduction product (platinum / tantalum sulfide@tantalum oxide / carbon matrix). Next, air was introduced, and oxidation was carried out at 290℃ for 5 hours with a heating rate of 10℃ / min to obtain the oxidation product (platinum oxide@tantalum oxide / carbon matrix). The oxidation product obtained above was dispersed in deionized water, and 18.5 mg of cobalt chloride hexahydrate was added. After rotary evaporation to dryness, the resulting powder was heated to 900 °C at a heating rate of 5 °C / min and held at that temperature for 2 h. Then, it was cooled to room temperature at a rate of 5 °C / min to finally obtain a composite material with a tandem structure (platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to cobalt in the platinum-cobalt intermetallic compound is 3:1, the mass percentage of tantalum oxide is 14%, and the mass percentage of the platinum-cobalt intermetallic compound is 30%).

[0042] Example 3 100 mg of Ketjenblack EC-600JD was uniformly ultrasonically dispersed in 50 mL of ethanol, and then 78.7 mg of tantalum ethoxide was added and stirred until homogeneous. The ethanol was removed by rotary evaporation to obtain the first mixture (tantalum oxide / carbon matrix). The first mixture obtained above was placed in a crucible, and then a mixture of argon and hydrogen sulfide (volume ratio of 95:5) was introduced at a flow rate of 0.2 L / min and sulfided at 350 °C for 2 h with a heating rate of 5 °C / min to obtain the sulfided product (tantalum sulfide@tantalum oxide / carbon matrix). The sulfide product obtained above was dispersed in ethanol, and 436.5 mg of chloroplatinic acid hexahydrate was added. After rotary evaporation to dryness, a second mixture (platinum oxide / tantalum sulfide@tantalum oxide / carbon matrix) was obtained. The second mixture obtained above was reduced for 2 hours at 300°C under a mixed atmosphere of argon and hydrogen (volume ratio of 95:5, flow rate of 0.2 L / min) and a heating rate of 5°C / min to obtain the reduction product (platinum / tantalum sulfide@tantalum oxide / carbon matrix). Next, air was introduced, and oxidation was carried out at 280℃ for 6 hours with a heating rate of 8℃ / min to obtain the oxidation product (platinum oxide@tantalum oxide / carbon matrix). After dispersing the above-obtained oxidation product in deionized water, 200.5 mg of cobalt chloride hexahydrate was added, and the mixture was evaporated to dryness. The resulting powder was then heated to 1000 °C at a heating rate of 20 °C / min and held at that temperature for 1 h. Finally, it was cooled to room temperature at a rate of 5 °C / min to obtain a composite material with a tandem structure (platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to cobalt in the platinum-cobalt intermetallic compound is 1:1, the mass percentage of tantalum oxide is 12%, and the mass percentage of the platinum-cobalt intermetallic compound is 60%).

[0043] Example 4 100 mg of Ketjenblack EC-600JD was uniformly ultrasonically dispersed in 50 mL of ethanol, and then 78.7 mg of tantalum ethoxide was added and stirred until homogeneous. The ethanol was removed by rotary evaporation to obtain the first mixture (tantalum oxide / carbon matrix). The first mixture obtained above was placed in a crucible, and then a mixture of argon and hydrogen sulfide gas (volume ratio of 95:5) was introduced at a flow rate of 0.3 L / min and sulfided at 400 °C for 2 h with a heating rate of 10 °C / min to obtain the sulfided product (tantalum sulfide@tantalum oxide / carbon matrix). The sulfide product obtained above was dispersed in ethanol, and 516.1 mg of chloroplatinic acid hexahydrate was added. After rotary evaporation to dryness, a second mixture (platinum oxide / tantalum sulfide@tantalum oxide / carbon matrix) was obtained. The second mixture obtained above was reduced for 2 hours at 400°C under a mixed atmosphere of argon and hydrogen (volume ratio of 95:5, flow rate of 0.3 L / min) with a heating rate of 10°C / min to obtain the reduction product (platinum / tantalum sulfide@tantalum oxide / carbon matrix). Next, air was introduced, and oxidation was carried out at 300℃ for 4 hours with a heating rate of 5℃ / min to obtain the oxidation product (platinum oxide@tantalum oxide / carbon matrix). The oxidation product obtained above was dispersed in deionized water, and 79 mg of cobalt chloride hexahydrate was added. After rotary evaporation to dryness, the resulting powder was heated to 900 °C at a heating rate of 10 °C / min and held at that temperature for 2 h. Then, it was cooled to room temperature at a rate of 10 °C / min to finally obtain a composite material with a tandem structure (platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to cobalt in the platinum-cobalt intermetallic compound is 3:1, the mass percentage of tantalum oxide is 12%, and the mass percentage of the platinum-cobalt intermetallic compound is 60%).

[0044] Example 5 A carbon-based composite material was prepared according to Example 1, wherein cobalt chloride hexahydrate was replaced with ferric chloride hexahydrate, and the composition included 46 mg tantalum ethoxide, 103.2 mg chloroplatinic acid hexahydrate, and 53.8 mg ferric chloride hexahydrate. The final composite material with a tandem structure (platinum-iron intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to iron in the platinum-iron intermetallic compound is 1:1, the mass percentage of tantalum oxide is 14%, and the mass percentage of the platinum-iron intermetallic compound is 30%).

[0045] Example 6 A carbon-based composite material was prepared according to Example 1, wherein cobalt chloride hexahydrate was replaced with nickel chloride hexahydrate, and the composition was 46 mg tantalum ethoxide, 102 mg chloroplatinic acid hexahydrate, and 46.8 mg nickel chloride hexahydrate. The final composite material with a tandem structure (platinum-nickel intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to nickel in the platinum-nickel intermetallic compound is 1:1, the mass percentage of tantalum oxide is 14%, and the mass percentage of the platinum-nickel intermetallic compound is 30%).

[0046] Performance testing Test Example 1 Figures 1-4 Transmission electron microscopy (TEM) images of the composite materials obtained in Examples 1-4, respectively. Figures 1-4 It can be seen that most of the nanoparticles have a particle size in the range of 5~20nm and are uniformly dispersed.

[0047] The experiment used a glassy carbon rotating disk electrode from Pine Instruments as the working electrode, with a geometric area of ​​0.196 cm². 2 The counter electrode was a platinum sheet electrode, and the reference electrode was a mercurous sulfate electrode (Hg / Hg₂SO₄). Oxygen reduction polarization curves were measured using linear sweep voltammetry (LSV) in an oxygen-saturated 0.1M HClO₄ solution, with a scan potential range of 0.05V to 1.05V (vs. RHE), a scan rate of 10mV / s, and a working electrode rotation speed of 1600 rpm. Accelerated aging tests (ADT) were performed in an oxygen-saturated 0.1M HClO₄ solution, with 5000 cyclic voltammetric (CV) scans continuously performed at a scan rate of 100mV / s within a potential range of 0.6V to 1.0V (vs. RHE).

[0048] The electrochemically active area (ECSA) of all samples was obtained by calculating the charge in the hydrogen adsorption region of the CV curves. The ECSA of the composite materials obtained in Examples 1-6 were 69m. 2 / g Pt 70.8m 2 / g Pt 69.9m 2 / gPt 73.5m 2 / g Pt 65.3m 2 / g Pt 64.8m 2 / g Pt After 30,000 cycles of ADT testing, ECSA decreased by 26%, 25%, 23%, 21%, 26%, and 23%, respectively.

[0049] Comparative Example 1 100 mg of Ketjenblack EC-600JD was uniformly ultrasonically dispersed in 50 mL of ethanol, then 46 mg of tantalum ethoxide was added and the mixture was stirred until homogeneous. The ethanol was removed by rotary evaporation to obtain a first mixture (tantalum oxide / carbon matrix). 102 mg of chloroplatinic acid hexahydrate and 47 mg of cobalt chloride hexahydrate were added to the first mixture, and after rotary evaporation to dryness, the resulting powder was heated to 900 °C at a rate of 10 °C / min and held at that temperature for 2 h. Then, it was cooled to room temperature at a rate of 10 °C / min to obtain a tandem composite material (platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, platinum-cobalt intermetallic compound / tantalum oxide@carbon matrix, wherein the molar ratio of platinum to cobalt in the platinum-cobalt intermetallic compound is 1:1, the mass percentage of tantalum oxide is 14%, and the mass percentage of the platinum-cobalt intermetallic compound is 30%). The ECSA of the composite material obtained in the comparative example was 69.5 m. 2 / g Pt After 30,000 cycles of ADT testing, ECSA decreased by 48%.

[0050] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A carbon-based composite material, characterized in that, Includes a carbon matrix and modified transition metal oxides supported on the carbon matrix; The modified transition metal oxide includes a transition metal oxide and a platinum-based intermetallic compound supported on the transition metal oxide.

2. The carbon matrix composite material according to claim 1, characterized in that, The transition metal oxide includes at least one of tantalum oxide, zirconium oxide, hafnium oxide, and niobium oxide. The carbon matrix includes at least one of conductive carbon black, graphene, and carbon nanotubes. The mass percentage of transition metal oxidation in the carbon matrix composite material is 10-30%.

3. The carbon matrix composite material according to claim 1, characterized in that, The platinum-based intermetallic compound comprises platinum and an auxiliary metal; the auxiliary metal comprises at least one of iron, cobalt, and nickel; The molar ratio of platinum to auxiliary metal in the platinum-based intermetallic compound is 1:1 or 3:1; The platinum-based intermetallic compound has a loading percentage of 30-60% in the carbon matrix composite material.

4. The method for preparing the carbon matrix composite material according to any one of claims 1 to 3, characterized in that, Includes the following steps: A first mixture is obtained by first mixing a transition metal source, a carbon matrix, and an organic solvent, and then removing the organic solvent. The first mixture was sulfided in a sulfur-containing atmosphere to obtain a sulfided product; The sulfide product, platinum source, and organic solvent are mixed in a second mixture, and after removing the organic solvent, a second mixture is obtained. The second mixture was subjected to a first reduction and oxidation in sequence to obtain an oxidation product; The oxidation product, auxiliary metal source, and water are mixed in a third step. After removing the water, the resulting product is subjected to a second reduction to obtain the carbon matrix composite material.

5. The preparation method according to claim 4, characterized in that, The transition metal source includes at least one of tantalum source, zirconium source, hafnium source and niobium source; The tantalum source includes at least one of tantalum ethoxide, tantalum n-butoxide, and tantalum chloride. The zirconium source includes at least one of zirconium ethoxide, zirconium n-butoxide, and zirconium chloride; The hafnium source includes at least one of ethanol hafnium, n-butanol hafnium, and hafnium chloride; The niobium source includes at least one of niobium ethanol, niobium n-butoxide, and niobium chloride.

6. The preparation method according to claim 4, characterized in that, The sulfur-containing atmosphere includes a mixed atmosphere of hydrogen sulfide and argon or carbon disulfide with argon as the carrier gas. The volume ratio of argon to hydrogen sulfide in the mixed atmosphere is 95:5 to 75:

25. The flow rate of carbon disulfide using argon as the carrier gas is 0.1~0.3 L / min; The vulcanization temperature is 300~400℃, the heating rate is 3~10℃ / min, and the holding time is 2~5h.

7. The preparation method according to claim 4, characterized in that, The platinum source includes chloroplatinic acid hexahydrate; The mass ratio of the sulfide product to the platinum source is 0.5~1:1; The first reduction is carried out in a hydrogen-containing atmosphere, which includes a mixture of argon and hydrogen, wherein the volume ratio of argon to hydrogen in the mixture is 95:5; and the flow rate of the hydrogen-containing atmosphere is 0.2~0.3 L / min. The temperature of the first reduction is 250~300℃, the heating rate is 5~10℃ / min, and the holding time is 1~3h.

8. The preparation method according to claim 4, characterized in that, The oxidation is carried out in an air atmosphere, the oxidation temperature is 280~300℃, the heating rate is 5~10℃ / min, and the holding time is 2~6h.

9. The preparation method according to claim 4, characterized in that, The auxiliary metal source includes at least one of iron source, cobalt source and nickel source; The iron source includes at least one of ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric acetate, ferric acetylacetone, and ferric citrate; the cobalt source includes at least one of cobalt chloride hexahydrate, anhydrous cobalt chloride, cobalt nitrate hexahydrate, cobalt acetylacetone, cobalt sulfate, dicobalt ethylenediaminetetraacetate, and hexaamminecobalt trichloride; the nickel source includes at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel hydroxide, and nickel acetylacetone. The second reduction is carried out in a hydrogen-containing atmosphere, which includes a mixture of argon and hydrogen, wherein the volume ratio of argon to hydrogen in the mixture is 95:5; and the flow rate of the hydrogen-containing atmosphere is 0.3~0.8 L / min. The second reduction temperature is 900~1000℃, the heating rate is 5~20℃ / min, and the holding time is 1~4h; After the second reduction, the product is further cooled to room temperature; the cooling rate is 5~10℃ / min.

10. The application of the carbon-based composite material according to any one of claims 1 to 3 or the composite material prepared by the preparation method according to any one of claims 4 to 9 as a catalyst in electrocatalytic oxygen reduction.

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