A platinum-iron alloy catalyst containing cerium atomic layers and a method for producing the same

Abstract

The application discloses a platinum-iron alloy catalyst containing a cerium atomic layer and a preparation method thereof, and belongs to the technical field of new energy catalysis. The preparation method comprises the following steps: (1) adding a carbon carrier, a structure directing agent and a dispersion aid into a mixed solvent of ethanol and ultrapure water; (2) dropping a solution containing a cerium compound into the mixed solvent, and adding a basic precipitant solution; (3) performing heat treatment; (4) dispersing in a liquid medium, and adding a platinum precursor and a transition metal precursor; (5) evaporating and removing the solvent; and (6) performing heat treatment to obtain the platinum-iron alloy catalyst containing the cerium atomic layer. The interface cerium atomic layer of the catalyst serves as a catalyst electronic structure adjusting component, provides electrons for the platinum-iron ordered alloy, enriches the platinum surface electrons, and also destroys the platinum-iron alloy surface dipole moment, thereby reducing the catalyst work function, making the PtFe alloy surface electrons more easily escape, realizing systematic reconstruction of the platinum-iron ordered alloy surface electronic structure, and improving the intrinsic catalytic activity of the oxygen reduction reaction.

Description

Technical Field

[0001] This invention relates to the field of new energy catalytic materials technology, specifically to a platinum-iron alloy catalyst containing cerium atomic layers and its preparation method. Background Technology

[0002] Proton exchange membrane fuel cells (PtFe) are considered a core direction of clean energy conversion technology due to their advantages such as high energy density, low operating temperature, and zero emissions. However, the oxygen reduction reaction (ORR) kinetics at the cathode are slow, requiring highly active platinum-iron catalysts to reduce overpotential and improve cell efficiency. Nevertheless, the scarcity and high cost of platinum resources severely restrict the commercialization of fuel cells. To reduce platinum usage and improve its catalytic performance, the main technical approach followed by research and industry is to construct alloy structures of platinum with inexpensive transition metals (such as Fe, Co, Ni, and Cu), utilizing ligand effects and crystal stress effects to regulate the electronic structure of platinum and optimize its adsorption energy for oxygen-containing intermediates, thereby enhancing intrinsic activity. Among these candidate inexpensive transition metals, Fe stands out due to its extremely high natural abundance. As one of the most common elements, iron's crustal abundance is several orders of magnitude higher than that of cobalt and nickel, further enhancing the cost reduction potential and large-scale application prospects of platinum-iron (PtFe) catalysts.

[0003] Introducing rare earth elements (especially cerium) has the potential to enhance the intrinsic activity of catalysts. This is mainly based on: 1) the excellent oxygen storage and release capacity of cerium oxides and the reversible Ce³⁺. + / Ce 4+ Redox couples may help alleviate the poisoning of intermediate species at the reaction interface; 2) There may be strong electronic interactions between cerium oxide and platinum, stabilizing the electronic state of platinum. However, in existing technologies, the introduction of cerium is mainly through physical mixing or surface modification. In this approach, cerium species are mainly distributed on the catalyst surface or support, and their interaction with the active centers of the platinum-iron ordered alloy is weak and indirect, making it difficult to regulate the electronic structure of the platinum-based alloy, and easily introducing additional resistance at the interface. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention provides a platinum-iron alloy catalyst containing a cerium atom layer and its preparation method. The method involves uniformly coating a carbon support with a cerium dioxide nanolayer; then introducing platinum and transition metal precursors into the carbon support coated with the nano-cerium dioxide layer, followed by heat treatment in a reducing atmosphere. During this process, the platinum and iron precursors are reduced on the surface of the cerium dioxide layer, further nucleating, growing, alloying, and becoming ordered. Simultaneously, oxygen is lost from the surface of the cerium dioxide nanolayer, exposing the outermost cerium atoms, which form a strong support interaction with the platinum-iron alloy phase. The interfacial cerium atom layer, as a component regulating the electronic structure of the catalyst, not only provides electrons to the ordered platinum-iron alloy but also disrupts the surface dipole moment of the platinum-iron alloy, causing a systematic reconstruction of the electronic structure on the catalyst surface, thereby effectively reducing the work function of the catalyst.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a method for preparing a platinum-iron alloy catalyst containing a cerium atomic layer is provided, the innovation of which lies in the following steps: (1) The carbon carrier, structure directing agent and dispersing agent are placed in a mixed medium of ethanol and deionized water, and a uniformly dispersed carbon suspension system is obtained by ultrasonic treatment. (2) Under continuous stirring, the solution containing cerium compound was gradually added dropwise to the above carbon suspension system. After ultrasonic homogenization, an alkaline precipitant was injected. The resulting mixed system was subjected to ultrasonic treatment and constant temperature stirring adsorption treatment, and then transferred to a closed reaction device for heat treatment. After the reaction was completed, the carbon carrier wrapped with cerium dioxide nanolayer was obtained by cooling, filtration, washing and drying. (3) The carbon support wrapped with the obtained cerium dioxide nanolayer is dispersed in a liquid medium, and platinum precursor and transition metal precursor are added. After dispersion treatment, a homogeneous slurry is formed, and then the dry precursor mixed powder is obtained by solvent removal. (4) The precursor mixed powder was heat-treated in a reducing atmosphere protected by inert gas, and then acid-washed, filtered, washed and dried to obtain a platinum-iron alloy catalyst.

[0006] Preferably, in step (1), the volume ratio of ethanol to ultrapure water in the mixed medium is 1:1-1:9; the carbon carrier is one of Ketjen Black EC-300J, Ketjen Black EC-600JD, acetylene black, Cabot BP2000, and Vulcan XC-72, and the concentration of the carbon carrier in the carbon suspension system is 1-10 mg / mL.

[0007] Preferably, the structure directing agent in step (1) is one of anhydrous citric acid, sodium citrate, potassium citrate, calcium citrate, ammonium citrate, diammonium hydrogen citrate, stearic acid, and sodium dodecylbenzene sulfonate, and the mass ratio of the structure directing agent to the carbon support is 1:1-10:1.

[0008] Preferably, the dispersing agent in step (1) is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium hexadecyl sulfate, dihexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, sodium octadecyl sulfate, heptadecanyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecyl sulfonate, and decadecyltrimethylammonium bromide; the mass ratio of the dispersing agent to the carbon support is 1:1-10:1.

[0009] Preferably, the concentration of the cerium-containing compound solution in step (2) is 0.015~0.039 mol / L, and the volume ratio of the cerium-containing compound solution to the carbonaceous suspension system is 1:2~1:5.

[0010] Preferably, the alkaline precipitant in step (2) is one of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, or ammonia water, the concentration of the alkaline precipitant solution is 0.5-1 mol / L, and the mass ratio of alkali to carbon carrier in the alkaline precipitant is 1:1-20:1.

[0011] Preferably, the heat treatment conditions in step (2) are: temperature of 100-200℃ and time of 2-16h; the washing conditions are: washing with a mixture of ethanol and deionized water until neutral.

[0012] Preferably, in step (3), the liquid medium is one of ethanol, acetone, or deionized water; The platinum precursor is one or more of dihydroxytetramineplatinum, chloroplatinic acid, acetylacetone platinum, platinum nitrate, and ethanolamine hydroxyplatinum; The transition metal precursor is one or more of the following: iron acetylacetonate, ferric chloride, ferric nitrate, ferric sulfate, cobalt acetylacetonate, cobalt chloride, cobalt nitrate, cobalt sulfate, nickel acetylacetonate, nickel chloride, nickel nitrate, and nickel sulfate; The homogeneous slurry contains 1-3 g / L of carbon support coated with cerium dioxide nanolayers, 0.75-1.5 g / L of platinum precursor, and 0.67-4.04 g / L of transition metal precursor; wherein the molar ratio of platinum to transition metal is 1:1 to 1:3.

[0013] Preferably, the heat treatment conditions in step (4) are: the heat treatment temperature is 700-1100 ℃, the time is 1-5 h, and the heating rate is 5-50 ℃ / min.

[0014] The present invention also provides a platinum-iron alloy catalyst containing cerium atomic layers prepared by the above preparation method.

[0015] The principle of this invention is as follows: First, a uniform carbon support dispersion system is set up to avoid local thickening or vacancies in the subsequent CeO2 nanolayer, ensuring uniform distribution of the cerium source, providing a basis for the continuous formation of the subsequent interface cerium atom layer, and preventing local blockage of the electron transport path.

[0016] Secondly, setting up a carbon support wrapped with a cerium dioxide nanolayer is equivalent to constructing a "cerium source library". The CeO2 nanolayer provides a fixed and accessible cerium source for subsequent steps, confining cerium atoms to the surface of the carbon support. This ensures that after high-temperature reduction, oxygen loss of cerium atoms forms an atomic layer at the "CeO2-PtFe alloy" interface, rather than diffusing into the PtFe alloy bulk phase and causing ineffective doping. This provides a locked path for the directional transfer of electrons.

[0017] Then, platinum and transition metal precursors were introduced into a carbon support coated with a nano-cerium dioxide layer and heat-treated in a reducing atmosphere. During this process, the platinum and transition metal precursors were reduced on the surface of the cerium dioxide layer, further nucleating, growing, alloying, and becoming ordered. Simultaneously, oxygen was lost from the surface of the cerium dioxide nanolayer, exposing the outermost cerium atoms to form an interfacial cerium atom layer that interacts strongly with the platinum-iron alloy phase. This interfacial cerium atom layer, acting as a catalyst electronic structure modulator, not only provides electrons to the ordered platinum-iron alloy but also disrupts the surface dipole moment of the platinum-iron alloy, causing a systematic reconstruction of the catalyst surface electronic structure. This effectively reduces the work function of the catalyst, making it easier for electrons to escape from the PtFe alloy surface.

[0018] Furthermore, the introduction of the cerium atomic layer at the interface enhances the interaction between the PtFe alloy support and the catalyst, improves the structural stability of the catalyst, inhibits the migration and aggregation of active components during electrocatalysis, and also gives it good long-term durability in oxygen reduction catalysis.

[0019] This invention provides a platinum-iron alloy catalyst containing cerium atomic layers and its preparation method, which has the following beneficial effects: (1) The cerium atom layer at the interface of the catalyst of the present invention serves as a catalyst electronic structure regulating component, providing electrons to the platinum-iron ordered alloy, thereby enriching the electrons on the platinum surface. Furthermore, the cerium atom layer at the interface disrupts the dipole moment on the surface of the platinum-iron alloy, reduces the work function of the catalyst, and makes it easier for electrons on the surface of the PtFe alloy to escape. The regulation of the cerium atom layer at the interface significantly improves the electron transfer efficiency, realizes the systematic reconstruction of the electronic structure on the surface of the platinum-iron ordered alloy, and significantly enhances the intrinsic catalytic activity of the oxygen reduction reaction.

[0020] (2) The introduction of the cerium atom layer at the interface in this invention enhances the interaction between the PtFe alloy and the support through electronic interaction, improves the structural stability of the catalyst, and inhibits the migration and aggregation of active components during electrocatalysis, thereby enhancing the stability and durability of the catalyst in the oxygen reduction reaction process.

[0021] (3) Compared with uncontrolled PtFe alloy catalysts, the catalyst of the present invention can achieve higher current density and higher mass activity at the same overpotential, thus significantly reducing the amount of platinum used and exhibiting higher cost-effectiveness. This meets the key requirement of reducing the manufacturing cost of fuel cell stacks and is an important indicator for commercial application. Attached Figure Description

[0022] Figure 1 This is a transmission electron microscope image of the catalyst prepared in Example 1 of the present invention.

[0023] Figure 2 This is a high-resolution transmission electron microscope image of the catalyst prepared in Example 1 of the present invention.

[0024] Figure 3 The X-ray diffraction patterns are those of the catalysts prepared in Example 1 and Comparative Example 1 of this invention.

[0025] Figure 4 The above are XPS images of the catalysts Pt4f prepared in Example 1 and Comparative Example 1 of this invention.

[0026] Figure 5 This is an O1s XPS fitting image of the catalyst prepared in Example 1 of the present invention.

[0027] Figure 6 This is an O1s XPS fitting diagram of the catalyst prepared in Comparative Example 2 of this invention.

[0028] Figure 7 The above are the ultraviolet photoelectron spectroscopy (UPS) spectra of the catalysts prepared in Example 1 and Comparative Example 1 of this invention. Figure 8 UPS diagrams of the catalysts prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention. Figure 9 The CV curves are for the catalysts prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention.

[0029] Figure 10 The LSV curves are for the catalysts prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention.

[0030] Figure 11 The CV curve of the catalyst in Example 1 of this invention after 20,000 cycles (0.6-0.95V) in a N2-saturated 0.1M HClO4 solution.

[0031] Figure 12 The LSV curve of the catalyst in Example 1 of this invention after 20,000 cycles (0.6-0.95V) in a N2-saturated 0.1M HClO4 solution.

[0032] Figure 13 The CV curve of the catalyst of Comparative Example 1 of this invention after 20,000 cycles (0.6-0.95V) in a 0.1M HClO4 solution saturated with N2.

[0033] Figure 14 The LSV curve of the catalyst of Comparative Example 1 of this invention after 20,000 cycles (0.6-0.95V) in a 0.1M HClO4 solution saturated with N2.

[0034] Figure 15 The graph shows the electrochemical area loss rate test results of the catalysts of Examples 1, 2, 3, 4 and Comparative Example 1 after 20,000 cycles (0.6-0.95V) in a N2-saturated 0.1M HClO4 solution.

[0035] Figure 16 The graph shows the results of the mass activity loss rate test of Example 1, Comparative Example 1, and commercial Pt / C catalysts after 20,000 cycles (0.6-0.95V) in N2-saturated 0.1M HClO4 solution. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the content described.

[0037] The cerium-containing compound is one of the following: cerium nitrate, cerium sulfate, cerium ammonium sulfate, cerium bromide, cerium iodide, cerium acetylacetone, cerium chloride, and cerium fluoride. Example 1 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 50 mg of carbon support (Ketjen Black EC-300J), 100 mg of anhydrous citric acid, and 50 mg of hexadecyltrimethylammonium bromide were added to a mixed solution of 18 mL of water and 2 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0038] (2) Under magnetic stirring (800 rpm), 5 mL of 0.024 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0039] (3) 5 mL of 0.5 mol / L NaOH solution was added dropwise to suspension B during magnetic stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 160 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0040] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of acetone solution, 32.8 mg of platinum acetylacetonate and 29.8 mg of iron acetylacetonate were added, and after sonication for 1 h, a homogeneous slurry was formed. The slurry was stirred and adsorbed overnight in a water bath at 60 °C, and then dried at 60 °C to obtain a uniform powder.

[0041] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 850 °C (heating rate of 30 °C / min) for 5 h to obtain the powder. 60 mg of the powder was added to 20 mL of acetic acid solution with a concentration of 8.75 mol / L, and stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0042] Example 2 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 50 mg of carbon carrier (Ketjen Black EC-600JD), 100 mg of potassium citrate and 50 mg of sodium octadecyl sulfate were added to a mixed solution of 18 mL of water and 2 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0043] (2) Under magnetic stirring (800 rpm), 5 mL of 0.015 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0044] (3) 5 mL of 0.5 mol / L potassium hydroxide solution was added dropwise to suspension B during magnetic stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 160 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0045] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of acetone solution, 32.8 mg of dihydroxytetraammineplatinum and 29.8 mg of ferric chloride were added, and after sonication for 1 h, it was stirred and adsorbed overnight in a water bath at 60 °C. Then it was stirred and dried at 60 °C to obtain a uniform powder.

[0046] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 850 °C (heating rate of 35 °C / min) for 5 h, and the resulting powder was obtained. 60 mg of the powder was added to 20 mL of acetic acid solution with a concentration of 8.75 mol / L, and the mixture was stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0047] Example 3 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 50 mg of carbon carrier (Cabot BP2000), 100 mg of calcium citrate and 50 mg of sodium hexadecyl sulfate were added to a mixed solution of 18 mL of water and 2 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0048] (2) Under magnetic stirring (600 rpm), 5 mL of 0.015 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0049] (3) 5 mL of 0.5 mol / L calcium hydroxide solution was added dropwise to suspension B during magnetic stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (600 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 160 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0050] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of acetone solution, 32.8 mg of platinum nitrate and 29.8 mg of cobalt chloride were added, and after sonication for 1 h, it was stirred and adsorbed overnight in a water bath at 60 °C. Then it was stirred and dried at 60 °C to obtain a uniform powder.

[0051] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 850 °C (heating rate of 20 °C / min) for 5 h to obtain the powder. 60 mg of the powder was added to 30 mL of acetic acid solution with a concentration of 8.75 mol / L, and stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0052] Example 4 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 50 mg of carbon support (acetylene black), 100 mg of sodium citrate and 50 mg of octadecyltrimethylammonium bromide were added to a mixed solution of 18 mL of water and 2 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0053] (2) Under magnetic stirring (600 rpm), 5 mL of 0.039 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0054] (3) 10 mL of 0.5 mol / L ammonia solution was added dropwise to suspension B during magnetic stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 160 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0055] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of alcohol solution (ethanol), 24.78 mg of dihydroxytetramineplatinum and 33.45 mg of nickel chloride were added, and after sonication for 1 h, it was stirred and adsorbed overnight in a water bath at 60 °C. Then it was stirred and dried at 60 °C to obtain a uniform powder.

[0056] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 950 °C (heating rate of 30 °C / min) for 5 h to obtain the powder. 60 mg of the powder was added to 30 mL of acetic acid solution with a concentration of 8.75 mol / L, and stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0057] Example 5 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 60 mg of carbon support (Vulcan XC-72), 300 mg of ammonium citrate and 300 mg of dihexadecanyltrimethylammonium bromide were added to a mixed solution of 5 mL of water and 1 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0058] (2) Under magnetic stirring (600 rpm), 2 mL of 0.039 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0059] (3) 18.75 mL of 0.8 mol / L NaOH solution was added dropwise to suspension B during magnetic stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 100℃ for 16 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0060] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of alcohol solution, 24.78 mg of chloroplatinic acid and 33.45 mg of ferric nitrate were added, and after sonication for 1 h, it was stirred and adsorbed overnight in a water bath at 60 °C. Then it was stirred and dried at 60 °C to obtain a uniform powder.

[0061] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 700℃ (heating rate of 5℃ / min) for 5 h, and the resulting powder was obtained. 60 mg of the powder was added to 30 mL of acetic acid solution with a concentration of 8.75 mol / L, and the mixture was stirred and acid-washed at 60℃ for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0062] Example 6 This embodiment provides a method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, comprising the following steps: (1) 64 mg of carbon carrier (acetylene black), 448 mg of diammonium hydrogen citrate and 448 mg of hexadecyltrimethylammonium chloride were added to a mixed solution of 4 mL of water and 4 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0063] (2) Under magnetic stirring (600 rpm), 2.5 mL of 0.039 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0064] (3) 32 mL of 1 mol / L NaOH solution was added dropwise to suspension B while magnetically stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred at a constant temperature (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 200 °C for 10 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was separated by filtration to obtain solid material. The solid material was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain carbon support coated with cerium dioxide nanolayers.

[0065] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was dispersed in 30 mL of alcohol solution, 24.78 mg of chloroplatinic acid and 33.45 mg of ferric sulfate were added, and after sonication for 1 h, it was stirred and adsorbed overnight in a water bath at 60 °C. Then it was stirred and dried at 60 °C to obtain a uniform powder.

[0066] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined (heat-treated) at 1100℃ (heating rate of 50℃ / min) for 1 h, and the resulting powder was obtained. 60 mg of the powder was added to 30 mL of acetic acid solution with a concentration of 8.75 mol / L, and the mixture was stirred and acid-washed at 60℃ for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. The solid material was then dried under vacuum to obtain the platinum-iron ordered alloy catalyst.

[0067] Comparative Example 1 The difference between this comparative example and Example 1 is that no cerium metal precursor (a carbon support encapsulated by cerium dioxide nanolayers) was added in this comparative example; only a platinum-iron ordered alloy catalyst was prepared. The steps include: (1) Disperse 60 mg of carbon support (Ketjen Black EC-300J) in 30 mL of acetone solution, add 32.8 mg of platinum acetylacetonate and 29.8 mg of iron acetylacetonate, sonicate for 1 h, stir and adsorb overnight in a water bath at 60 °C, and then stir dry at 60 °C to obtain a uniform powder.

[0068] (2) The solid powder was packed into the reaction tube of a tubular furnace, and a mixture of argon and hydrogen gas was introduced, with the argon gas flow rate at 90 mL / min and the hydrogen gas flow rate at 10 mL / min. The mixture was calcined at 850 °C (heating rate at 30 °C / min) for 5 h, and the resulting powder was obtained. 60 mg of the powder was added to 20 mL of acetic acid solution with a concentration of 8.75 mol / L, and the mixture was stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. After vacuum drying, the platinum-iron alloy catalyst was obtained.

[0069] Comparative Example 2 The difference between this comparative example and Example 1 is that no metal precursor was added in this comparative example; only a carbon support coated with a cerium dioxide nanolayer was added. The steps include: (1) 50 mg of carbon support (Ketjen Black EC-300J), 100 mg of anhydrous citric acid, and 50 mg of hexadecyltrimethylammonium bromide were added to a mixed solution of 18 mL of water and 2 mL of alcohol and ultrasonically dispersed for 1 h to obtain suspension A.

[0070] (2) Under magnetic stirring (800 rpm), 5 mL of 0.024 mol / L cerium nitrate aqueous solution was slowly added dropwise to suspension A, and then ultrasonically dispersed for 1 h to obtain suspension B.

[0071] (3) 5 mL of 0.5 mol / L NaOH solution was added dropwise to suspension B while magnetically stirring. The mixture was then ultrasonically dispersed for 1 h and magnetically stirred (800 rpm) for 30 min to obtain suspension C. Suspension C was then poured into a high-pressure reactor and heated to 160 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction product was filtered to obtain a solid. The solid was washed with a mixture of ethanol and deionized water until neutral and then vacuum dried to obtain a carbon support coated with cerium dioxide nanolayers.

[0072] (4) The carbon support containing 60 mg of cerium dioxide nanolayer was added to 30 mL of acetone solution, sonicated for 1 h, and then stirred and adsorbed overnight in a water bath at 60 °C. After that, it was dried at 60 °C to obtain a uniform powder.

[0073] (5) The solid powder was packed into the reaction tube of a tubular furnace, and an argon-hydrogen mixture was introduced, with an argon flow rate of 90 mL / min and a hydrogen flow rate of 10 mL / min. The mixture was calcined at 850 °C for 5 h to obtain the powder. 60 mg of the powder was added to 20 mL of acetic acid solution with a concentration of 8.75 mol / L, and stirred and acid-washed at 60 °C for 6 h. After the reaction was completed, the liquid was removed by vacuum filtration, and the solid material was washed with a mixture of water and ethanol. After vacuum drying, the cerium dioxide-coated carbon support material was obtained.

[0074] Transmission electron microscopy (TEM) image of the catalyst prepared in Example 1 is shown below. Figure 1 As shown, the high-resolution transmission electron microscope image is as follows: Figure 2 As shown, through Figure 1 It was found that platinum-iron (PtFe) alloy nanoparticles with an average particle size of 4.38 ± 0.82 nm were uniformly loaded on the carbon support. Figure 2As shown, high-resolution TEM observation reveals that PtFe alloy nanoparticles grow on the surface of cerium dioxide.

[0075] The X-ray diffraction patterns of the catalysts prepared in Example 1 and Comparative Example 1 are as follows: Figure 3 As shown, the Pt4fXPS plot is as follows: Figure 4 As shown, from the XRD pattern ( Figure 3 As can be seen, diffraction peaks appear at 2θ = 24.0 °, 32.9 °, 41.8 °, 47.2 °, 49.2 °, 53.7 °, and 60.4 °, corresponding to the (001), (110), (111), (200), (002), (201), and (112) crystal plane diffraction of the PtFe ordered alloy, respectively, indicating the successful preparation of the platinum-iron ordered alloy. Compared with Comparative Example 1, the diffraction peak positions of the catalyst prepared in Example 1 systematically shift significantly towards lower angles, indicating that the introduction of cerium dioxide forms a strong support interaction with the platinum-iron ordered alloy. Figure 4 It can be seen that, compared with Comparative Example 1, the introduction of cerium significantly reduced the binding energy of Pt, and its Pt 4f peak decreased from 75.1 eV (Comparative Example 1) to 74.3 eV. This is because the support transferred electrons to platinum, resulting in Pt electron enrichment.

[0076] The O1s XPS fitting diagram of the catalyst prepared in Example 1 is shown below. Figure 5 As shown, the O1s XPS fitting plot of the catalyst prepared in Comparative Example 2 is as follows. Figure 6 As shown in Table 1, the concentrations of each atom in the catalysts prepared in Example 1 and Comparative Example 2 of this invention, as determined by XPS, are shown in Table 1.

[0077] A comparative analysis of the surface oxygen content of the materials prepared in Example 1 and Comparative Example 2 shows that the surface oxygen content of the material containing PtFe alloy and cerium dioxide-coated carbon (Example 1) is 5.96 at.%, significantly lower than the surface oxygen content of 10.7 at.% of the material containing only cerium dioxide-coated carbon (Comparative Example 2). This result indicates that the introduction of PtFe alloy into cerium dioxide-coated carbon leads to a decrease in the surface oxygen content of the system. Furthermore, by fitting the O1s XPS plot (… Figure 5 and Figure 6 It was found that, compared with the material in Comparative Example 2, the content of adsorbed oxygen (77.5%) and lattice oxygen (22.5%) was significantly reduced after the introduction of PtFe alloy in Example 1 (accounting for 47.4%), while the lattice oxygen content increased to 52.6%.

[0078] Table 1 The calculated Fermi levels and work function values ​​of the catalysts prepared in Examples 1-6 and Comparative Example 1 are shown in Table 2: Table 2 The above comparative results show that during the reduction of Pt and Fe precursors onto cerium dioxide-coated carbon to form an ordered PtFe alloy, oxygen on the cerium dioxide surface is consumed, and the surface cerium dioxide is reduced, forming a cerium atom layer at the interface between the PtFe alloy and cerium dioxide. This interfacial cerium atom layer interacts strongly with the PtFe alloy, significantly altering the electronic structure of the catalyst surface. Compared to Comparative Example 1, the Fermi level shift of the catalyst prepared in Example 1 is -0.13 eV, indicating that the interfacial cerium atom layer injects electrons into the system. Compared to the work function of the catalyst prepared in Comparative Example 1 (4.23 eV), the work functions of the catalysts in Examples 1-6 are reduced to 3.89-4.15 eV, indicating that the interfacial cerium atom layer disrupts the surface dipole moment of the PtFe alloy, leading to a decrease in the work function. This suggests that the catalyst prepared by the scheme of this invention is more likely to have its surface electrons transferred out.

[0079] Electrochemical tests were performed on Examples 1-4 and Comparative Example 1. The electrocatalytic oxygen reduction reaction of the catalyst in this invention was tested using a Chenhua CHI760E electrochemical workstation. All electrochemical tests were conducted using a standard three-electrode system. The test temperature was 25 ± 2 °C. The working electrode was a glassy carbon electrode (uniformly covered with a film solution, 5 mm in diameter), the reference electrode was a reversible hydrogen electrode (RHE) or a saturated calomel electrode (SCE), and the counter electrode was a graphite rod. The CV curves were measured in a N2-saturated 0.1 M HClO4 solution. Activation was first performed at a scan rate of 500 mV / s within the range of 0.05–1.1 V (vs. RHE) to obtain a stable CV curve. Then, the scan rate was set to 100 mV / s to obtain the final CV curve. The LSV curves were measured in an O2-saturated 0.1 M HClO4 solution with a potential range of 0.05–1.05 V (vs. RHE), a scan rate of 10 mV / s, and a rotation speed of 1600 rpm. Accelerated durability testing was conducted in a N2-saturated 0.1 M HClO4 solution, with low-potential ADT cycling within the range of 0.6–1.0 V (vs. RHE), at 100 mV / s, for 10,000 or 20,000 scans. The high-potential ADT cycling range is 1.0 - 1.5 V (vs. RHE), 100 mV / s, and 5000 scans.

[0080] The ultraviolet photoelectron spectroscopy (UPS) spectra of the catalysts prepared in Example 1 and Comparative Example 1 are shown below. Figure 7 As shown, the UPS diagrams of the catalysts prepared in Examples 1, 2, 3, 4, and Comparative Example 1 are as follows. Figure 8 As shown, by Figure 7 and Figure 8As shown in Table 2, the formed interfacial cerium atomic layer interacts strongly with the PtFe alloy, significantly altering the surface electronic structure of the catalyst. Compared to Comparative Example 1, the Fermi levels of the catalysts prepared in Examples 1–6 shifted by -0.13 eV, -0.08 eV, -0.09 eV, -0.12 eV, -0.11 eV, and -0.13 eV, respectively, indicating that the interfacial cerium atomic layer injects electrons into the catalyst system. Meanwhile, the work function of the catalyst in Comparative Example 1 was 4.23 eV, while the work functions of Examples 1–6 decreased to 3.98 eV, 4.01 eV, 4.15 eV, 3.89 eV, 4.09 eV, and 4.08 eV, respectively. This decrease is attributed to the interfacial cerium atomic layer disrupting the surface dipole moment of the PtFe alloy, thereby reducing the energy required for electron escape.

[0081] The catalysts of Examples 1-6, Comparative Example 1, and a commercial Pt / C catalyst (commercial Pt / C catalyst is currently the most commonly used cathode oxygen reduction reaction catalyst in proton exchange membrane fuel cells (PEMFC). Its basic structure consists of platinum (Pt) nanoparticles uniformly loaded on the surface of a carbon support to form a platinum / carbon composite structure) were subjected to 20,000 cycles (0.6-0.95V) in a N2-saturated 0.1M HClO4 solution. The electrochemical area values ​​and mass activity values ​​of the catalysts prepared in Examples 1-6 and Comparative Example 1 are shown in Table 3.

[0082] Table 3 Table 3 shows that Example 1 has the highest electrochemical active area (99.82 m² / g) and mass activity (589.1 mA / mg). After 20,000 cycles of durability testing, its electrochemical active area loss rate is only 34.6%, significantly better than Comparative Example 1 (48.1%). The electrochemical active area loss rates of the other examples are also lower than those of Comparative Example 1. This indicates that the present invention effectively improves the initial activity and long-term operational stability of the catalyst by introducing an interfacial cerium atom layer. Although Comparative Example 1 exhibits a high initial mass activity (713.2 mA / mg), its low electrochemical active area and the highest durability loss rate confirm its insufficient structural stability. The durability loss rates (13.3%~38.2%) of Examples 2-6 are all lower than those of Comparative Example 1, further verifying the universality of the interfacial cerium atom layer modification strategy in improving catalyst stability.

[0083] The CV and LSV curves of the catalysts prepared in Examples 1, 2, 3, 4, and Comparative Example 1 are shown in Figures 9 and 10, respectively. Figure 9 and 10Furthermore, referring to Table 3, the electrocatalytic active areas of the catalysts in Examples 1-4 modified with an interfacial cerium atomic layer were all superior to those of the unmodified Comparative Example 1. The introduction of the interfacial cerium atomic layer not only optimized the surface electronic structure of the catalyst but also significantly improved its electrocatalytic active area and noble metal utilization efficiency.

[0084] The electrochemical area loss rate test results of the catalysts prepared in Examples 1-6 and Comparative Example 1 are shown in Table 4. Table 4 shows that: Example 1 has the highest original electrochemical active area (99.82 m² / g), and after 10,000 cycles and 20,000 cycles of durability testing, it still maintains 83.32 m² / g and 65.33 m² / g, respectively, with an area retention rate significantly better than that of Comparative Example 1; the area retention rates of the catalysts in Examples 2-6 after 20,000 cycles of durability testing are also better than those of Comparative Example 1, indicating that the present invention effectively inhibits the aggregation and loss of active components and improves the structural stability of the catalyst by introducing an interfacial cerium atom layer.

[0085] The CV and LSV curves after catalyst recycling in Example 1 are shown below. Figure 11 and 12 As shown, the CV and LSV curves of the catalyst in Comparative Example 1 after cycling are respectively as follows: Figure 13 and 14 As shown, by Figure 12-15 Referring to Table 4, the catalyst of Example 1 maintained high current density and mass activity after 20,000 accelerated durability cycles, with a significantly lower decay rate than Comparative Example 1. This indicates that the present invention, by introducing an interfacial cerium atom layer to modify the PtFe alloy, effectively enhances the structural stability of the catalyst, inhibits the agglomeration and loss of active components, and significantly improves the long-term operational durability of the catalyst. In contrast, although the catalyst of Comparative Example 1 possesses certain initial activity, its durability is poor, making it difficult to meet the requirements for long catalyst life in practical applications.

[0086] Table 4 The electrochemical area loss rate test results after cycling of the catalysts in Example 1 (Ce-PtFe / C), Comparative Example 1 (PtFe-C), and the commercial Pt / C catalyst are shown in the figure below. Figure 15 As shown, Figure 15As shown, the initial electrochemical area of ​​Example 1 (99.83 mA / cm²) is significantly higher than that of Comparative Example 1 (43.12 mA / cm²) and commercial Pt / C (75 mA / cm²). After 20,000 cycles, Example 1 still maintains 65.33 mA / cm², while commercial Pt / C decays to 52 mA / cm², and Comparative Example 1 decays significantly to 22.41 mA / cm². This further confirms that the catalyst of the present invention has excellent activity retention during long-term operation, and its durability is significantly better than that of Comparative Example 1 and existing commercial catalysts.

[0087] The results of the mass activity loss rate test after cycling for Example 1 (Ce-PtFe / C), Comparative Example 1 (PtFe-C), and commercial Pt / C catalysts are shown in the figure below. Figure 16 As shown in Table 5, the mass activity loss rate test results of the catalysts prepared in Examples 1-6 and Comparative Example 1 are shown in Table 5. Table 5 shows that although Comparative Example 1 has the highest original mass activity (713.2 mA / mg), its decay is extremely significant. After 10,000 cycles, it drops to 383.63 mA / mg, and after 20,000 cycles, it further drops to 342.29 mA / mg, with an activity loss rate of 52.0%.

[0088] Table 5 In contrast, the catalysts of Examples 1-6 exhibited the best durability performance, specifically: Example 1: The original mass activity was 589.12 mA / mg, and after 10,000 cycles it remained at 582.12 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 523.26 mA / mg, with an activity loss rate of only 7.2%, which is much lower than the 52.0% of Comparative Example 1.

[0089] Example 2: The original mass activity was 356.1 mA / mg, and after 10,000 cycles it remained at 323.34 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 309.62 mA / mg, with an activity loss rate of only 13.3%, which is much lower than the 52.0% of Comparative Example 1.

[0090] Example 3: The original mass activity was 372.39 mA / mg, and after 10,000 cycles it remained at 304.56 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 295.67 mA / mg, with an activity loss rate of only 20.6%, which is much lower than the 52.0% of Comparative Example 1.

[0091] Example 4: The original mass activity was 397.9 mA / mg, and after 10,000 cycles it remained at 309.84 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 285.29 mA / mg, with an activity loss rate of only 28.3%, which is much lower than the 52.0% of Comparative Example 1.

[0092] Example 5: The original mass activity was 372.1 mA / mg, and after 10,000 cycles it remained at 316.2 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 248.9 mA / mg, with an activity loss rate of only 33.1%, which is much lower than the 52.0% of Comparative Example 1.

[0093] Example 6: The original mass activity was 387.1 mA / mg, and after 10,000 cycles it still maintained 252.1 mA / mg, with almost no activity decay; after 20,000 cycles it was still as high as 239.6 mA / mg, with an activity loss rate of only 38.2%, which is much lower than the 52.0% of Comparative Example 1.

[0094] like Figure 16 As shown, the catalyst (Ce-PtFe / C) of Example 1 maintained a mass activity of 530.0 mA / mg after 20,000 cycles, while the catalyst (PtFe-C) of Comparative Example 1 had decayed to 342.2 mA / mg, and the commercial Pt / C catalyst had also decreased to 80.0 mA / mg. This indicates that by introducing an interfacial cerium atom layer, the present invention significantly improves the long-term operational stability of the catalyst while maintaining a high initial activity, and its durability performance is comprehensively superior to that of the comparative example and existing commercial catalysts.

[0095] Electrochemical test results show that the cerium-doped platinum-iron alloy nanomaterials not only have a larger electrochemical active area and higher ORR mass activity, but also a significantly reduced loss rate in long-term durability tests, indicating that the low work function platinum alloy nanomaterials prepared in this invention have better comprehensive catalytic performance.

[0096] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a platinum-iron alloy catalyst containing cerium atomic layers, characterized in that: Includes the following steps: (1) The carbon carrier, structure directing agent and dispersing agent are placed in a mixed medium of ethanol and deionized water, and a uniformly dispersed carbon suspension system is obtained by ultrasonic treatment. (2) Under continuous stirring, the solution containing cerium compound was gradually added dropwise to the above carbon suspension system. After ultrasonic homogenization, an alkaline precipitant was injected. The resulting mixed system was subjected to ultrasonic treatment and constant temperature stirring adsorption treatment, and then transferred to a closed reaction device for heat treatment. After the reaction was completed, the carbon carrier wrapped with cerium dioxide nanolayer was obtained by cooling, filtration, washing and drying. (3) The carbon support wrapped with the obtained cerium dioxide nanolayer is dispersed in a liquid medium, and platinum precursor and transition metal precursor are added. After dispersion treatment, a homogeneous slurry is formed, and then the dry precursor mixed powder is obtained by solvent removal. (4) The precursor mixed powder was heat-treated in a reducing atmosphere protected by inert gas, and then acid-washed, filtered, washed and dried to obtain a platinum-iron alloy catalyst.

2. The method for preparing the platinum-iron alloy catalyst containing cerium atomic layers according to claim 1, characterized in that: In step (1), the volume ratio of ethanol to ultrapure water in the mixed medium is 1:1-1:9; the carbon support is one of Ketjen Black EC-300J, Ketjen Black EC-600JD, acetylene black, Cabot BP2000, and Vulcan XC-72, and the concentration of the carbon support in the carbon suspension system is 1-10 mg / mL.

3. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: The structure directing agent mentioned in step (1) is one of anhydrous citric acid, sodium citrate, potassium citrate, calcium citrate, ammonium citrate, diammonium hydrogen citrate, stearic acid, and sodium dodecylbenzene sulfonate. The mass ratio of the structure directing agent to the carbon support is 1:1 to 10:

1.

4. The method for preparing the platinum-iron alloy catalyst containing a cerium atom layer according to claim 1, characterized in that: The dispersing agent mentioned in step (1) is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium hexadecyl sulfate, dihexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, sodium octadecyl sulfate, heptadecanyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecyl sulfonate, and decadecyltrimethylammonium bromide; the mass ratio of the dispersing agent to the carbon support is 1:1-10:

1.

5. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: The concentration of the cerium-containing compound solution in step (2) is 0.015~0.039 mol / L, and the volume ratio of the cerium-containing compound solution to the carbonaceous suspension system is 1:2~1:

5.

6. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: The alkaline precipitant mentioned in step (2) is one of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, or ammonia water. The concentration of the alkaline precipitant solution is 0.5-1 mol / L, and the mass ratio of alkali to carbon carrier in the alkaline precipitant is 1:1-20:

1.

7. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: The heat treatment conditions in step (2) are: temperature 100-200℃, time 2-16h; the washing conditions are: wash with a mixture of ethanol and deionized water until neutral.

8. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: In step (3), the liquid medium is one of ethanol, acetone, or deionized water; The platinum precursor is one or more of dihydroxytetramineplatinum, chloroplatinic acid, acetylacetone platinum, platinum nitrate, and ethanolamine hydroxyplatinum; The transition metal precursor is one or more of the following: iron acetylacetonate, ferric chloride, ferric nitrate, ferric sulfate, cobalt acetylacetonate, cobalt chloride, cobalt nitrate, cobalt sulfate, nickel acetylacetonate, nickel chloride, nickel nitrate, and nickel sulfate; The homogeneous slurry contains 1-3 g / L of carbon support coated with cerium dioxide nanolayers, 0.75-1.5 g / L of platinum precursor, and 0.67-4.04 g / L of transition metal precursor; wherein the molar ratio of platinum to transition metal is 1:1 to 1:

3.

9. The method for preparing the platinum-iron alloy catalyst containing a cerium atomic layer according to claim 1, characterized in that: The conditions for heat treatment in step (4) are: the heat treatment temperature is 700-1100 ℃, the time is 1-5 h, and the heating rate is 5-50 ℃ / min.

10. A platinum-iron alloy catalyst containing cerium atomic layers prepared by the preparation method according to any one of claims 1-9.

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