Rare earth monatomic modified pyrolysis ZIF-8 derived porous carbon carrier loaded Pt-based alloy oxygen reduction catalyst as well as preparation method and application thereof

Abstract

The invention discloses a rare earth monatomic modified pyrolysis ZIF-8 derived porous carbon carrier loaded Pt-based alloy oxygen reduction catalyst and a preparation method and application thereof, and aims to solve the sintering phenomenon existing in the high-temperature pyrolysis step in the preparation process of a Pt-based alloy ORR catalyst in the prior art. The rare earth monatomic modified ZIF-8 carbonized derived porous carbon loaded Pt-based alloy ORR catalyst prepared by the invention solves the problems of loss of an electrochemical active surface area caused by migration, aggregation and falling of particles in a catalytic reaction process, reduction of intrinsic activity of the catalyst caused by precipitation of transition metal under a severe condition and the like in the prior art. The catalyst shows excellent ORR catalytic activity and stability in three-electrode and membrane electrode tests, and can effectively inhibit excessive growth of metal particles in a pyrolysis process, migration, aggregation and falling of the metal particles in a catalytic process, and dissolution of transition metal in an acidic medium.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and application technology, specifically relating to a rare earth single-atom modified pyrolysis ZIF-8 derived porous carbon support supported Pt-based alloy oxygen reduction catalyst, its preparation method and application. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) fueled by hydrogen are considered one of the most promising technologies for replacing traditional fossil fuels and achieving carbon neutrality due to their excellent energy density and energy utilization efficiency, green and pollution-free emissions, and advantages such as fast start-up and low noise. Combining hydrogen production technology with water electrolysis and renewable energy power generation technology is a crucial strategy for effectively storing and utilizing seasonally fluctuating renewable energy sources across time and space, and for building a future green, environmentally friendly, and efficient energy system. The efficient utilization of hydrogen energy is a vital link in the hydrogen production-storage-use industrial chain.

[0003] In hydrogen-oxygen fuel cells, oxygen reduction (ORR) and hydrogen oxidation (HOR) half-reactions occur at the anode and cathode, respectively. Because the former has a complex reaction pathway and numerous steps involving multiple proton-coupled electron transfer steps, its reaction rate is about six orders of magnitude lower than the latter, severely limiting the overall reaction rate of the hydrogen-oxygen fuel cell. Therefore, there is a strong demand for highly efficient ORR catalysts to drive the cathode ORR reaction. Currently, non-precious metal catalysts, represented by Fe-NC, still have a performance gap compared to Pt-based catalysts. Therefore, commercially available ORR catalysts are still mainly based on carbon-supported platinum (Pt / C) and its alloys. To improve the catalytic activity and long-term stability of carbon-supported Pt-based catalysts, many researchers have conducted extensive studies and proposed a series of methods to enhance catalytic activity or stability, such as alloying Pt with Group VIII metals of the fourth period, forming intermetallic compounds based on the alloying, and constructing a core-shell structure with the intermetallic compound as the core and pure Pt as the shell. However, problems still exist, such as excessive particle growth caused by the high-temperature pyrolysis process of preparing intermetallic compounds, weak interaction between metal particles and the support, and dissolution of transition metal atoms with low standard reduction potential in acidic media. These problems lead to reduced Pt atom utilization, metal particle migration, aggregation and shedding during catalysis, and reduced catalytic activity due to loss of ligands and strain effects, which seriously affect the long-term stability of the catalyst.

[0004] To address the issues of sintering during the high-temperature pyrolysis step in the preparation of existing Pt-based alloy ORR catalysts, loss of electrochemical active surface area due to particle migration, aggregation, and shedding during the catalytic reaction, and reduction of intrinsic catalyst activity due to transition metal precipitation under harsh conditions, it is imperative to propose a rare-earth single-atom modified ZIF-8 carbonized porous carbon-supported Pt-based alloy ORR catalyst. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a rare earth single-atom modified pyrolysis ZIF-8 derived porous carbon support supported Pt-based alloy oxygen reduction catalyst, its preparation method and application.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a rare-earth single-atom modified pyrolysis ZIF-8 derived porous carbon support-supported Pt-based alloy oxygen reduction catalyst, comprising, Zinc nitrate hexahydrate and dimethylimidazole were dissolved in methanol and stirred to form a ZIF-8 precursor. After centrifugation, washing and drying, the precursor was pyrolyzed and carbonized under a reducing atmosphere. The product was acid washed, separated and washed by vacuum filtration until the filtrate was neutral, and dried to obtain a porous nitrogen-doped carbon support derived from pyrolyzed ZIF-8. The above-mentioned porous nitrogen-doped carbon support was dispersed in ethanol, urea and rare earth salts were added, and after stirring and mixing evenly, the mixture was evaporated by rotary evaporation. The product was collected and pyrolyzed in an inert atmosphere. The product was acid-washed, filtered and separated, and washed until the filtrate was neutral. After drying, rare earth single-atom modified ZIF-8 carbonized derivatized porous carbon was obtained. The rare earth single-atom modified ZIF-8 carbonized derivatized porous carbon was dispersed in ethanol, and platinum-containing compounds and transition metal compounds were added. After stirring evenly, the mixture was rotary evaporated. The product was collected and pyrolyzed in a reducing atmosphere. The product was acid-washed, filtered and separated, and washed until the filtrate was neutral. After drying, a black powder was obtained. The black powder was pyrolyzed in a reducing atmosphere to obtain a rare earth single-atom modified pyrolysis ZIF-8 derived porous carbon support supported Pt-based alloy oxygen reduction catalyst.

[0009] In a preferred embodiment of the preparation method described in this invention, the mass ratio of zinc nitrate hexahydrate to dimethylimidazole is 1:1-10.

[0010] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the porous nitrogen-doped carbon support, urea, and rare earth salt is 1:10:0.2-1.

[0011] As a preferred embodiment of the preparation method described in this invention, the rare earth salt is an anhydrous or water-containing rare earth compound soluble in ethanol, including erbium nitrate, gadolinium chloride, terbium chloride, lanthanum nitrate, cerium nitrate, and dysprosium chloride.

[0012] As a preferred embodiment of the preparation method described in this invention, the mass ratio of the rare earth single-atom modified ZIF-8 carbide-derived porous carbon, the platinum-containing compound, and the transition metal compound is 4:1-4:0.5-2.

[0013] In a preferred embodiment of the preparation method described in this invention, the platinum-containing compound includes chloroplatinic acid hexahydrate, platinum acetylacetonate, or a solution thereof.

[0014] In a preferred embodiment of the preparation method described in this invention, the transition metal compound is a chloride or nitrate soluble in ethanol, including iron, cobalt, or nickel.

[0015] In a preferred embodiment of the preparation method described in this invention, the ratio of platinum atoms to transition metal atoms in the amount of platinum-containing compound and transition metal compound is 3-1:1-3.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a rare earth single-atom modified pyrolysis ZIF-8 derived porous carbon support supported Pt-based alloy oxygen reduction catalyst prepared by a preparation method.

[0017] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of a rare earth single-atom modified pyrolysis ZIF-8 derived porous carbon support for Pt-based alloy oxygen reduction catalyst in hydrogen-oxygen fuel cells, methanol fuel cells, and zinc-air batteries.

[0018] Beneficial effects of this invention: This invention provides a method for preparing a rare-earth single-atom modified ZIF-8 carbonized derivatized porous carbon-supported Pt-based alloy ORR catalyst. The prepared catalyst has uniform particle size and dispersion, resulting in high Pt atom utilization. The metal particles are loaded within the pores, and the physical confinement effect of the pores and the anchoring effect caused by the electronic interaction between the rare-earth single-atom sites and the Pt-based alloy particles effectively suppress the sintering phenomenon of metal particles during pyrolysis and the migration, aggregation, and shedding phenomenon during the catalytic reaction. The electron-enriched Pt shell inhibits the oxidative dissolution of Pt and the dissolution of internal transition metals, effectively improving the stability of the catalyst. The regulation of the electronic structure of Pt by the rare-earth single-atom sites also optimizes the intrinsic catalytic activity of Pt sites, improving the ORR catalytic activity. The above-mentioned effects on the catalyst's activity and stability have been verified by a combination of three-electrode and membrane electrode systems, fully demonstrating the practical application potential of this catalyst. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 The nitrogen adsorption-desorption curves and specific surface areas of the support and finished catalyst prepared in Example 1 of this invention were obtained by BET testing. Figure 2 This is a TEM image of the rare earth single-atom modified ZIF-8 carbonized porous carbon-supported Pt-based alloy ORR catalyst prepared in Example 1 of this invention. Figure 3 XRD image of the rare earth single-atom modified ZIF-8 carbonized porous carbon-supported Pt-based alloy ORR catalyst prepared in Example 1 of this invention; Figure 4 Linear sweep voltammetry curves and stability tests of the rare earth single-atom modified ZIF-8 carbonized porous carbon-supported Pt-based alloy ORR catalyst prepared in Example 1 of the present invention for three-electrode testing. Figure 5 The polarization and power density curves and stability tests of the rare earth single-atom modified ZIF-8 carbonized porous carbon-supported Pt-based alloy ORR catalyst prepared in Example 1 of the present invention were used for membrane electrode testing. Figure 6 Linear sweep voltammetry curves and stability tests of the ZIF-8 carbonized derivatized porous carbon directly supported Pt-based alloy ORR catalyst prepared in Comparative Example 1 of this invention were performed using a three-electrode method. Figure 7The polarization and power density curves and stability tests of the ZIF-8 carbonized derived porous carbon directly supported Pt-based alloy ORR catalyst prepared for Comparative Example 1 of this invention were used for membrane electrode testing. Detailed Implementation

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0023] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0024] Table 1

[0025] Example 1 This embodiment provides a method for preparing a rare-earth single-atom modified pyrolysis ZIF-8 derived porous carbon support for Pt-based alloy oxygen reduction catalyst: (1) Dissolve 3 g of zinc nitrate hexahydrate in 60 mL of methanol to prepare solution A; dissolve 6.5 g of dimethylimidazole in 60 mL of methanol to prepare solution B; while stirring, add solution B to solution A and continue stirring at room temperature for 24 h. Centrifuge the suspension produced by the reaction at 10,000 rpm and wash with ethanol at least 3 times. Dry the obtained white solid in an oven at 60 °C overnight. Then grind the obtained white solid powder evenly and put it into a quartz boat, place it in a tube furnace, and pyrolyze it at 950 °C for 1 h in an atmosphere containing 10% hydrogen and 90% argon to obtain black solid powder. Grind the black solid powder evenly and acid wash it with 1 M H2SO4 at 80 °C for 12 h. Then vacuum filter to separate the solid and wash it with ultrapure water until the filtrate is neutral. Dry the obtained solid in an oven at 60 °C overnight to obtain the porous nitrogen-doped carbon support (NC) derived from pyrolysis ZIF-8.

[0026] (2) Dissolve 500 mg of urea and 15 mg of erbium nitrate hexahydrate in 50 mL of ethanol. After stirring until homogeneous, add 100 mg of NC and stir magnetically for 12 h. Remove the solvent from the resulting suspension by rotary evaporation. Then, load the product into a quartz boat and place it in a tube furnace. Pyrolyze the product at 950 °C for 1 h in an argon atmosphere. Wash the resulting black powder with 0.1 M HClO4 at 80 °C for 12 h. Then, separate the solid by vacuum filtration and wash with ultrapure water until the filtrate is neutral. Dry the solid in an oven at 60 °C overnight. The product is the rare earth Er single-atom doped porous carbon support (Er SA -NC).

[0027] (3) Mix 14 mg of ferric chloride hexahydrate with 1.35 mL of 7.4 mg ferric chloride solution. Pt Add 20 mL of ethanol to a chloroplatinic acid hexahydrate solution (e.g., Fe:Pt atomic ratio 1:1), stir well, and then add 50 mg of Er. SA -NC, magnetically stirred for 12 h. The resulting suspension was solvent-removed by rotary evaporation, and the product was then loaded into a quartz boat and placed in a tube furnace. Pyrolysis was performed at 850 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by cooling to 300 °C at a rate of 10 °C / min, and then allowed to cool naturally to room temperature. The pyrolysis product was acid-washed with 0.1 M HClO4 at room temperature for 12 h, then the solid was separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The obtained solid was dried overnight in a 60 °C oven, and the black solid powder was then placed back into the tube furnace and pyrolyzed at 400 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by natural cooling to room temperature. The resulting product is the rare earth Er single-atom modified ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst (PtFe / Er). SA -NC).

[0028] Regarding NC and Er in Example 1 SA -NC and PtFe / Er SA -NC was used to perform N2 adsorption-desorption tests and analysis, and the results are as follows: Figure 1 As shown, the prepared pyrolytic ZIF-8 derived porous nitrogen-doped carbon support has a specific surface area as high as 1543 m². 2 / g, with abundant micropores and mesopores, is beneficial for the subsequent dispersion of single-atom Er sites and the physical confinement of metal particles, thereby suppressing sintering during pyrolysis and migration, aggregation, and detachment of metal particles during catalytic reactions. In contrast, Er SA The specific surface area of ​​-NC did not change significantly, remaining at 1434 m². 2 / g; while PtFe / Er SA The specific surface area of ​​-NC is significantly lower than that of NC, proving that the metal particles are mainly loaded inside the pores, which leads to the decrease in specific surface area and fully utilizes the confinement effect of porous carbon support.

[0029] For PtFe / Er in Example 1 SA -NC was used for TEM characterization, and the results are as follows Figure 2 As shown, the PtFe intermetallic compound particles in the prepared catalyst are densely but uniformly dispersed on the Er single-atom doped porous carbon support. The particle size is uniform and the distribution is relatively concentrated, with an average particle size of only 2.97 nm. The small particle size proves that the sintering phenomenon during the pyrolysis process is significantly suppressed, effectively improving the utilization rate of noble metal Pt atoms.

[0030] For PtFe / Er in Example 1 SA -NC was used for XRD characterization, and the results are as follows Figure 3 As shown, the appearance of superlattice diffraction peaks that can be attributed to crystal planes (001) and (110) fully demonstrates the formation of PtFe intermetallic compounds. The diffraction peaks as a whole shift to higher angles to varying degrees, proving that there is a certain degree of lattice compression.

[0031] For PtFe / Er in Example 1 SA - NC was used to perform linear sweep voltammetry on the three-electrode system, and this test was repeated after accelerated aging tests with different numbers of potential cycles to characterize the catalyst stability. The results are as follows: Figure 4 As shown, the catalyst's initial half-wave potential is as high as 0.930 V, exceeding that of Comparative Example 1 and the commercial Pt / C catalyst. More notably, after 50,000 cycles of accelerated aging testing, the PtFe / Er catalyst... SA -NC's half-wave potential only showed a decrease of 11 mV, demonstrating a significant improvement in stability compared to Comparative Example 1 and the commercial Pt / C catalyst.

[0032] For PtFe / Er in Example 1 SA -NC conducted polarization curve and power density tests in fuel cells, and repeated the tests after different numbers of potential cycling accelerated aging tests to characterize the stability of the catalyst in practical applications. The results are as follows: Figure 5 As shown. Under hydrogen-air conditions, the peak power density can reach 1.09 W / cm². 2 Rated power density reaches 953.5 mW / cm³ 2 Furthermore, after 50,000 cycles of accelerated aging test, the peak power density retention rate reached 89.6%, and the catalytic activity and stability were significantly improved compared with Comparative Example 1 and commercial Pt / C catalyst, fully demonstrating its potential for practical application.

[0033] Example 2 The difference from Example 1 is that in step (2), the amount of erbium nitrate hexahydrate is 30 mg; and in step (3), the amount of ferric chloride hexahydrate is 7 mg with a concentration of 7.4 mg. Pt The chloroplatinic acid hexahydrate solution was 0.675 mL, and the rest was the same as in Example 1.

[0034] The rare earth Er single-atom modified ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst of Example 2 was tested in three electrodes and fuel cells, and its stability was also verified. The results showed that it also achieved a considerable degree of improvement in activity and stability.

[0035] Example 3 The difference from Example 1 is that step (3) is 15 mg of cobalt chloride hexahydrate, the atomic ratio of Co and Pt is 1:1, and the rest is the same as Example 1. The resulting Example 3 is a rare earth Er single atom modified ZIF-8 carbonized derivatized porous carbon supported PtCo intermetallic compound ORR catalyst.

[0036] The rare earth Er single-atom modified ZIF-8 carbonized porous carbon-supported PtCo intermetallic compound ORR catalyst of Example 3 was tested in three electrodes and fuel cells, and its stability was also verified. The results showed that it also achieved a considerable degree of improvement in activity and stability.

[0037] Example 4 The difference from Example 1 is that step (2) uses 15 mg of gadolinium chloride hexahydrate; otherwise, it is the same as Example 1. The resulting Example 4 is a rare earth Gd single-atom modified ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst (PtFe / Gd). SA -NC).

[0038] The rare earth Gd single-atom modified ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst of Example 4 was tested in three electrodes and fuel cells, and its stability was also verified. The results showed that it also achieved a considerable degree of improvement in activity and stability.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that, instead of introducing rare earth Er single-atom sites, NC was directly used as a support to load PtFe intermetallic compound particles. Specifically: 3 g of zinc nitrate hexahydrate was dissolved in 60 mL of methanol to prepare solution A; 6.5 g of dimethylimidazole was dissolved in 60 mL of methanol to prepare solution B; while stirring, solution B was added to solution A, and stirring was continued at room temperature for 24 h. The resulting suspension was centrifuged at 10,000 rpm and washed with ethanol at least three times. The resulting white solid was dried overnight in an oven at 60 °C. The resulting white solid powder was then ground evenly and placed in a quartz boat, which was then placed in a tube furnace and pyrolyzed at 950 °C for 1 h in an atmosphere containing 10% hydrogen and 90% argon to obtain a black solid powder. The black solid powder was ground evenly and then acid-washed with 1 M H₂SO₄ at 80 °C for 12 h. The solid was then separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The resulting solid was dried overnight in an oven at 60 °C, which is the porous nitrogen-doped carbon support (NC) derived from pyrolytic ZIF-8.

[0040] 14 mg of ferric chloride hexahydrate and 1.35 mL of a 7.4 mg solution were mixed. Pt 20 mL of ethanol was added to a chloroplatinic acid hexahydrate solution (Fe:Pt atomic ratio approximately 1:1), and the mixture was stirred until homogeneous. Then, 50 mg of NC was added, and the mixture was magnetically stirred for 12 h. The solvent in the resulting suspension was removed by rotary evaporation. The product was then loaded into a quartz boat and placed in a tube furnace. The furnace was pyrolyzed at 850 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon. The temperature was then reduced to 300 °C at a rate of 10 °C / min, and subsequently allowed to cool naturally to room temperature. The pyrolysis product was acid-washed with 0.1 M HClO4 at room temperature for 12 h, and then the solid was separated by vacuum filtration. The solid was washed with ultrapure water until the filtrate was neutral. The obtained solid was dried in an oven at 60 °C overnight. Then the black solid powder was put back into a tube furnace and pyrolyzed at 400 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon. After that, it was naturally cooled to room temperature. The product obtained is the ZIF-8 carbonized derivatized porous carbon supported PtFe intermetallic compound ORR catalyst (PtFe / NC).

[0041] Linear sweep voltammetry of the ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst of Comparative Example 1 was performed using a three-electrode system. This test was repeated after accelerated aging tests with different numbers of potential cycles to characterize the catalyst stability. Figure 6 As shown, its initial half-wave potential is 0.906 V, and after 50,000 cycles of accelerated aging test, the half-wave potential decays by 36 mV.

[0042] The polarization curves and power density of the ZIF-8 carbonized porous carbon-supported PtFe intermetallic compound ORR catalyst (Comparative Example 1) in a fuel cell were tested. This test was repeated after accelerated aging tests with different numbers of potential cycles to characterize the catalyst stability. Figure 7 As shown, compared to Example 1, its initial peak power density is only 982.65 mW / cm². 2 And after 50,000 cycles of accelerated aging testing, it decayed to 714.6 mW / cm². 2 The attenuation rate was as high as 27.3%.

[0043] Comparative Example 2 This comparative example differs from Example 1 in that it does not use a porous nitrogen-doped carbon support derived from pyrolytic ZIF-8, but instead uses commercial Vulcan XC-72 carbon black. Specifically: 500 mg of urea and 15 mg of erbium nitrate hexahydrate were dissolved in 50 mL of ethanol and stirred until homogeneous. Then, 100 mg of Vulcan XC-72 was added, and the mixture was magnetically stirred for 12 h. The solvent was removed from the resulting suspension by rotary evaporation. The product was then loaded into a quartz boat and placed in a tube furnace for pyrolysis at 950 °C for 1 h under an argon atmosphere. The resulting black powder was acid-washed with 0.1 M HClO4 at 80 °C for 12 h. The solid was then separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The solid was dried overnight in an oven at 60 °C. The product is the rare earth Er single-atom doped Vulcan XC-72 carbon support (Er...). SA -XC-72).

[0044] 14 mg of ferric chloride hexahydrate and 1.35 mL of a 7.4 mg solution were mixed. Pt Add 20 mL of ethanol to a chloroplatinic acid hexahydrate solution (e.g., Fe:Pt) and stir until homogeneous. The atomic ratio of Fe to Pt is approximately 1:1. Then add 50 mg of Er... SA-XC-72, magnetically stirred for 12 h. The resulting suspension was solvent-removed by rotary evaporation, and the product was then loaded into a quartz boat and placed in a tube furnace. Pyrolysis was performed at 850 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by cooling to 300 °C at a rate of 10 °C / min, and then allowed to cool naturally to room temperature. The pyrolysis product was acid-washed with 0.1 M HClO4 at room temperature for 12 h, then the solid was separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The obtained solid was dried overnight in a 60 °C oven, and the black solid powder was then placed back into the tube furnace and pyrolyzed at 400 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by natural cooling to room temperature. The resulting product is the rare earth Er single-atom modified Vulcan XC-72 carbon support-supported PtFe intermetallic compound ORR catalyst (PtFe / Er). SA -XC-72).

[0045] The rare earth Er single-atom modified Vulcan XC-72 carbon support-supported PtFe intermetallic compound ORR catalyst of Comparative Example 2 was tested in three electrodes and fuel cells, and its stability was also verified. Compared with Example 1, its activity and stability were significantly reduced.

[0046] Comparative Example 3 This comparative example differs from Example 1 in that it does not contain a fourth-period Group VIII metal. Specifically: 3 g of zinc nitrate hexahydrate was dissolved in 60 mL of methanol to prepare solution A; 6.5 g of dimethylimidazole was dissolved in 60 mL of methanol to prepare solution B; while stirring, solution B was added to solution A, and stirring was continued at room temperature for 24 h. The resulting suspension was centrifuged at 10,000 rpm and washed with ethanol at least three times. The resulting white solid was dried overnight in an oven at 60 °C. The resulting white solid powder was then ground evenly and placed in a quartz boat, which was then placed in a tube furnace and pyrolyzed at 950 °C for 1 h in an atmosphere containing 10% hydrogen and 90% argon to obtain a black solid powder. The black solid powder was ground evenly and then acid-washed with 1 M H₂SO₄ at 80 °C for 12 h. The solid was then separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The resulting solid was dried overnight in an oven at 60 °C, which is the porous nitrogen-doped carbon support (NC) derived from pyrolytic ZIF-8.

[0047] 500 mg of urea and 15 mg of erbium nitrate hexahydrate were dissolved in 50 mL of ethanol and stirred until homogeneous. Then, 100 mg of NC was added, and the mixture was magnetically stirred for 12 h. The solvent was removed from the resulting suspension by rotary evaporation. The product was then loaded into a quartz boat and placed in a tube furnace for pyrolysis at 950 °C for 1 h under an argon atmosphere. The resulting black powder was acid-washed with 0.1 M HClO4 at 80 °C for 12 h. The solid was then separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The solid was dried overnight in an oven at 60 °C. The product is the rare earth Er single-atom doped porous carbon support (Er). SA -NC).

[0048] 1.35 mL of solution containing 7.4 mg was used. Pt Add 20 mL of ethanol to a chloroplatinic acid hexahydrate solution ( / mL), stir well, and then add 50 mg of Er. SA -NC, magnetically stirred for 12 h. The resulting suspension was solvent-removed by rotary evaporation, and the product was then loaded into a quartz boat and placed in a tube furnace. Pyrolysis was performed at 850 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by cooling to 300 °C at a rate of 10 °C / min, and then allowed to cool naturally to room temperature. The pyrolysis product was acid-washed with 0.1 MHClO4 at room temperature for 12 h, then the solid was separated by vacuum filtration and washed with ultrapure water until the filtrate was neutral. The obtained solid was dried overnight in a 60 °C oven, and the black solid powder was then placed back into the tube furnace and pyrolyzed at 400 °C for 2 h in an atmosphere containing 5% hydrogen and 95% argon, followed by natural cooling to room temperature. The resulting product is the rare earth Er single-atom modified ZIF-8 carbonized derived porous carbon-supported Pt particle ORR catalyst (Pt / Er). SA -NC).

[0049] The rare earth Er single-atom modified ZIF-8 carbonized porous carbon-supported Pt particle ORR catalyst of Comparative Example 3 was tested in three electrodes and fuel cells, and its stability was also verified. Compared with Example 1, its activity was significantly reduced.

[0050] Comparative Example 4 Commercial Pt / C catalysts produced by Johnson Matthey in the UK.

[0051] The commercial Pt / C catalyst produced by Johnson Matthey (UK) in Comparative Example 4 was tested in both three-electrode and fuel cell environments to verify its stability. The commercial Pt / C catalyst showed an initial half-wave potential of only 0.878 V in the three-electrode test, which decreased by 37 mV after 50,000 accelerated aging cycles. The initial peak power density of the commercial Pt / C catalyst in the fuel cell test was only 922.4 mW / cm³. 2Furthermore, after 50,000 cycles of accelerated aging testing, its performance degraded to 717.2 mW / cm². 2 The attenuation rate reached 22.2%. Its activity and stability were significantly lower than those of Example 1.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a rare earth single atom decorated pyrolyzed ZIF-8 derived porous carbon supported Pt-based alloy oxygen reduction reaction catalyst, characterized in that: comprising, Zinc nitrate hexahydrate and dimethylimidazole are dissolved in methanol and stirred to form a ZIF-8 precursor, which is centrifuged, washed, dried, pyrolyzed in a reducing atmosphere, and then acid-washed, filtered, and washed until the filtrate is neutral, and dried to obtain a pyrolyzed ZIF-8-derived porous nitrogen-doped carbon support; The porous nitrogen-doped carbon support is dispersed in ethanol, and urea and a rare earth salt are added and stirred to form a mixture, which is rotary evaporated, pyrolyzed in an inert atmosphere, and then acid-washed, filtered, and washed until the filtrate is neutral, and dried to obtain a rare earth single-atom-modified ZIF-8 carbon-derived porous carbon; The rare earth single-atom-modified ZIF-8 carbon-derived porous carbon is dispersed in ethanol, and a platinum-containing compound and a transition metal compound are added and stirred to form a mixture, which is rotary evaporated, pyrolyzed in a reducing atmosphere, and then acid-washed, filtered, and washed until the filtrate is neutral, and dried to obtain a black powder; The black powder is pyrolyzed in a reducing atmosphere to obtain a rare earth single-atom-modified pyrolyzed ZIF-8-derived porous carbon support loaded with a Pt-based alloy oxygen reduction catalyst.

2. The production method according to claim 1, characterized by: The mass ratio of the zinc nitrate hexahydrate and the dimethylimidazole is 1:1-10.

3. The production method according to claim 1, wherein: The mass ratio of the porous nitrogen-doped carbon support, the urea, and the rare earth salt is 1:10:0.2-1.

4. The production method according to claim 3, characterized by: The rare earth salt is a rare earth compound that is anhydrous or contains crystal water and is soluble in ethanol, and includes erbium nitrate, gadolinium chloride, terbium chloride, lanthanum nitrate, cerium nitrate, and dysprosium chloride.

5. The production method according to claim 1, wherein: The mass ratio of the rare earth single-atom-modified ZIF-8 carbon-derived porous carbon, the platinum-containing compound, and the transition metal compound is 4:1-4:0.5-2.

6. The production method according to claim 5, characterized by: The platinum-containing compound includes chloroplatinic acid hexahydrate, platinum acetylacetonate, or a solution thereof.

7. The production method according to claim 5, wherein: The transition metal compound is a chloride or a nitrate that is soluble in ethanol and includes iron, cobalt, or nickel.

8. The production method according to claim 6, characterized by: The ratio of platinum to transition metal atoms in the amount of the platinum-containing compound and the transition metal compound is 3-1:1-3.

9. A rare earth single-atom-modified pyrolyzed ZIF-8-derived porous carbon support loaded with a Pt-based alloy oxygen reduction catalyst prepared by the method of any one of claims 1-8.

10. Use of the rare earth single-atom-modified pyrolyzed ZIF-8-derived porous carbon support loaded with a Pt-based alloy oxygen reduction catalyst of claim 9 in a hydrogen-oxygen fuel cell, a methanol fuel cell, or a zinc-air battery.

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