A high-loading cobalt-based single-atom catalyst for oxygen reduction and its preparation method
Cobalt single-atom catalysts were prepared by in-situ encapsulation of nitrogen-containing small metal molecules using MOF cage structures, solving the problems of high loading and cost, achieving excellent oxygen reduction catalytic performance, and promoting the development of fuel cells and metal-air batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2023-03-22
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies make it difficult to prepare cobalt-based single-atom catalysts with high loading, which limits their oxygen reduction catalytic activity and makes them costly and difficult to replace noble metal Pt/C catalysts.
A high-load cobalt single-atom catalyst was prepared by in-situ encapsulating nitrogen-containing metal molecules in a MOF cage structure, forming a ZnCo-ZIF precursor through a self-assembly reaction, and then pyrolyzing it at high temperature to avoid metal atom aggregation.
A high loading (4.03–4.08 wt%) of cobalt single-atom catalyst was achieved, with a half-wave potential of 0.88 V and a limiting diffusion current density of 6 mA·cm⁻². The catalytic activity was superior to that of commercial Pt/C catalysts, and the catalyst was low in cost and easy to operate.
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Figure CN116314867B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalysis technology, and relates to a method for preparing a high-load cobalt-based single-atom oxygen reduction catalyst using in-situ encapsulation technology, and particularly to a cobalt-based single-atom catalyst for oxygen reduction and its preparation method. Background Technology
[0002] The rapid development of modern society is largely driven by the massive combustion of fossil fuels. However, the excessive burning of fossil fuels inevitably leads to energy crises and environmental pollution. Therefore, developing clean energy sources and green energy conversion devices is extremely important. Fuel cells and metal-air batteries, with their advantages of clean fuels, high energy conversion rates, and zero pollution, are ideal solutions to these problems.
[0003] Fuel cells and metal-air batteries utilize oxygen as the cathode reactant in the oxygen reduction reaction, but the reaction kinetics are slow and the reaction is difficult to initiate, requiring a catalyst for propagation. Currently, platinum-based catalysts are commercially available oxygen reduction catalysts, but their high cost severely limits their further development and application. Therefore, developing low-cost oxygen reduction catalysts with excellent performance is a pressing technical challenge.
[0004] Transition metal carbon materials possess advantages such as high oxygen reduction catalytic activity, good stability, and low cost, making them ideal substitutes for the noble metal Pt. Studies have found that in both acidic and alkaline electrolytes, the intrinsic catalytic activity of various transition metals follows the order Fe > Co > Mn > Cu > Ni. Although Fe exhibits the best catalytic performance, its four-electron selectivity in the oxygen reduction process is poor due to the Fenton effect. Therefore, cobalt-based catalysts, with their superior overall performance, have broad development prospects.
[0005] Loading the transition metal cobalt in an atomically dispersed form onto N-doped C materials can effectively enhance their catalytic activity. This is because single-atom catalysts possess advantages such as high atom utilization, metal-support interaction, large surface free energy, and high selectivity, and their catalytic performance is expected to surpass that of commercially available Pt / C catalysts, driving the further development and application of energy devices. However, the current preparation of single-atom catalysts generally involves high-temperature pyrolysis, which easily leads to metal agglomeration, thereby reducing the loading of metal atoms and limiting the improvement of catalytic activity.
[0006] This invention utilizes the cage structure in MOF to encapsulate guest nitrogen-containing small metal molecules in situ within the cage. Thanks to the separating effect of the zinc nodes in the MOF framework and the spatial confinement effect of the MOF cage, a high-load cobalt single-atom catalyst is obtained after carbonization, exhibiting excellent catalytic activity. Summary of the Invention
[0007] The purpose of this invention is to propose a method for preparing a high-load cobalt single-atom catalyst by in-situ encapsulation of nitrogen-containing small metal molecules in a MOF cage. ICP-OES characterization shows that the catalyst has a cobalt single-atom loading of 4.03–4.08 wt%, thus exhibiting excellent oxygen reduction catalytic activity, with a half-wave potential of 0.88 V and a limiting diffusion current density of 6 mA·cm⁻¹. -2 This catalyst surpasses commercially available Pt / C catalysts. Its preparation method is simple, feasible, low-cost, and yields high efficiency, demonstrating excellent development prospects and the potential to further advance fuel cells and metal-air batteries.
[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0009] A method for preparing a high-load cobalt-based single-atom catalyst for oxygen reduction is disclosed. This invention introduces nitrogen-rich metal molecule tris(ethylenediamine)cobalt(III) chloride trihydrate during the self-assembly reaction of dimethylimidazolium with zinc nitrate and cobalt nitrate to form ZnCo-ZIF. This encapsulates the small molecule within the cage structure of the ZIF, achieving spatial confinement of the metal molecule and effectively preventing the aggregation of metal atoms during pyrolysis. After high-temperature carbonization, a cobalt-based single-atom catalyst with a loading of 4.03–4.08 wt% is obtained. The method includes the following steps:
[0010] (1) Anhydrous methanol and deionized water are mixed to obtain a mixed solvent. The volume ratio of anhydrous methanol to deionized water in the mixed solvent of step (1) is 1:1.5 to 2.
[0011] (2) Dissolve zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and tri(ethylenediamine)cobalt(III) chloride trihydrate in the mixed solvent obtained in step (1) and stir at room temperature for 8-12 min, and record as solution A; dissolve dimethylimidazole and polyvinylpyrrolidone in the mixed solvent obtained in step (1) and stir at room temperature for 8-12 min, and record as solution B; the molar ratio of cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole is 1:18:190, the amount of tri(ethylenediamine)cobalt(III) chloride trihydrate added in every 55 ml of solution A is 1 mmol, and the amount of polyvinylpyrrolidone added in every 55 ml of solution B is 7 g.
[0012] (3) Pour solution A into solution B and stir at room temperature for 20-40 min to synthesize MOFs through self-assembly with zinc and cobalt ions as central ions and dimethylimidazole as ligand. Simultaneously, during the self-assembly process, tris(ethylenediamine)cobalt(III) chloride trihydrate is encapsulated within the MOF cage, promoting cobalt dispersion. The mixed solution is placed in an oven for aging treatment to promote MOF grain growth. The product is separated by centrifugation, and then the product is washed by centrifugation using the mixed solvent obtained in step (1). The washed sample is then placed in an oven to dry overnight; the oven aging temperature is 40-80℃, and the time is 12-36 h.
[0013] (4) Place the dried sample into a tube furnace and pyrolyze it at 800-1000℃ for 2-4 hours under a nitrogen atmosphere to obtain the final product.
[0014] Furthermore, in step (1), the volume ratio of anhydrous methanol to deionized water in the mixed solvent is preferably 1:1.75.
[0015] Furthermore, the molar ratio of cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole is 1:18:190, the amount of tri(ethylenediamine)cobalt(III) chloride trihydrate added in each 55 ml solution A is 1 mmol, and the amount of polyvinylpyrrolidone added in each 55 ml solution B is 7 g.
[0016] Furthermore, after stirring solution A and solution B for 10 minutes, solution A is added to solution B, and stirring continues for 30 minutes.
[0017] Furthermore, the mixed solution was aged in a 60°C oven for 24 hours.
[0018] Furthermore, after centrifuging the sample, it was washed three more times with a mixed solvent, with the speed set at 10,000 rpm / min and the time set at 7 min.
[0019] Furthermore, after the dried sample was placed in a tube furnace, nitrogen gas was introduced for 1 hour at a flow rate of 60 mL / min, and then the temperature was increased at a rate of 2 °C / min and held at 900 °C for 3 hours.
[0020] A cobalt-based single-atom catalyst for oxygen reduction was prepared using the method described above.
[0021] Analysis of the innovative points of this invention: This invention uses zinc nitrate, cobalt nitrate, dimethylimidazole, tris(ethylenediamine)cobalt(III) chloride trihydrate, and polyvinylpyrrolidone as raw materials. At room temperature, nitrogen-containing small molecules are in-situ encapsulated using the cage structure of a MOF to obtain a ZnCo-ZIF precursor with a dodecahedral structure. Then, after high-temperature heat treatment, a Co single-atom catalyst with a particle size of approximately 100 nm is obtained. This catalyst has a high loading of 4.03 wt%, and its abundant single-atom active sites give it excellent oxygen reduction catalytic activity. Therefore, its half-wave potential reaches 0.88 V, and its limiting diffusion current density reaches 6 mA·cm⁻¹. -2 .
[0022] The beneficial effects of this invention are:
[0023] (1) This invention proposes a method for preparing Co single-atom catalysts, namely, using MOF cages to encapsulate nitrogen-containing metal molecules, effectively avoiding the aggregation of metal atoms, and obtaining Co single-atom catalysts with high loading.
[0024] (2) The ZIF precursor encapsulated with small molecules can be obtained by the self-assembly reaction of the reactants at room temperature, and then the catalyst can be obtained by one-step pyrolysis. The production process is simple and convenient, avoiding complex synthesis processes.
[0025] (3) Compared with the pure methanol solvent used in other methods, the present invention uses a mixed solvent of methanol and water, which reduces the use of organic solvents, lowers costs, and is more environmentally friendly.
[0026] (4) The catalyst prepared by this mixed dissolution has a size of less than 100 nm, which is smaller than the size of the catalyst prepared in pure methanol. It also has a rich microporous and mesoporous structure and a large specific surface area. This will accelerate the mass transfer and electron transfer of the oxygen reduction process, fully expose the active sites, and make it easier for oxygen molecules to be adsorbed and activated, thereby improving the oxygen reduction catalytic activity.
[0027] (5) Using zinc nitrate, cobalt nitrate and other raw materials, the cost is low, easy to control and scale up, and has good prospects for industrial application. Attached Figure Description
[0028] Figure 1 a is a scanning electron microscope image of the precursor in Comparative Example 2; Figure 1 b is a scanning electron microscope image of Comparative Example 2; Figure 1 c is a scanning electron microscope image of the precursor of Comparative Example 1; Figure 1 d is the scanning electron microscope image of Comparative Example 1; Figure 1 e is a scanning electron microscope image of the precursor of Example 1; Figure 1 f is a scanning electron microscope image of Example 1; Figure 1g is a transmission electron microscope image of Comparative Example 1; Figure 1 h is a transmission electron microscope image of Comparative Example 1; Figure 1 i is a transmission electron microscope image of Example 1; Figure 1 j is a transmission electron microscope image of Example 1; Figure 1 k is a spherical aberration electron microscope image of Example 1; Figure 1 l is a spherical aberration electron microscope image of Example 1;
[0029] Figure 2 The XRD patterns of the products prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown.
[0030] Figure 3 a is the XPS spectrum of the products prepared in Example 1 and Comparative Example 1; Figure 3 b is the XPS spectrum of the products prepared in Example 1 and Comparative Example 1;
[0031] Figure 4 a represents the cyclic voltammetry test curves of Example 1 under N2 and O2; Figure 4 b represents the linear sweep voltammetry curves of Example 1, Comparative Example 1, Comparative Example 2, and commercial 20% Pt / C. Figure 4 c represents the LSV curves of Example 1 at different rotational speeds; Figure 4 d is the KL fitting plot of Example 1; Figure 4 e represents the peroxide intermediate yield and electron transfer number n calculated from RRDE data. Specific implementation methods
[0032] The present invention will be further described below with reference to specific embodiments.
[0033] This invention utilizes a MOF cage structure to in-situ encapsulate nitrogen-containing small metal molecules to prepare a highly loaded and highly active oxygen reduction electrocatalyst. To further understand this invention, the electrocatalyst and its applications are described in detail below with reference to specific examples. However, this invention is not limited to these examples. Non-essential improvements and adjustments made by those skilled in the art under the core guiding principles of this invention are still within the scope of protection of this invention. Specific implementation methods are as follows:
[0034] Example 1
[0035] (1) Anhydrous methanol and deionized water are mixed in a volume ratio of 1:1.75 to obtain a mixed solvent.
[0036] (2) Dissolve 2.818 g of Zn(NO)3·6H2O, 0.153 g of Co(NO)3·6H2O, and 0.4 g of [Co(en)3]Cl3·3H2O in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 10 min to obtain solution A. Dissolve 8.21 g of 2-methylimidazole and 7 g of PVP in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 10 min to obtain solution B.
[0037] (3) Pour solution A into solution B, stir at room temperature for 30 min, and then place the mixture in a 60℃ oven for constant temperature aging for 24 h. Then centrifuge the product and wash it three times with the mixed solvent, and then dry it in a 60℃ oven overnight.
[0038] (4) The obtained precursor was placed in a nitrogen atmosphere at 2℃·min -1 The temperature was increased to 900℃ at a heating rate, held for 3 hours, and then automatically cooled to obtain the final product. ICP-OES characterization showed that the catalyst had a cobalt single-atom loading of 4.04 wt%.
[0039] Figure 1 e is a SEM image of the precursor prepared in Example 1. The precursor shows a regular dodecahedral structure, proving the successful synthesis of ZnCo-ZIF. Figure 1 f is the SEM image after carbonization. It can be seen that the product retains the initial morphology after carbonization, and the particle size is about 100 nm. It can be seen that small-sized ZIF particles can be prepared by in-situ encapsulation of nitrogen-containing metal molecules in a mixed solvent. Furthermore, the study found that the smaller the particle size, the higher the oxygen reduction catalytic activity of the catalyst. Figure 1 i and j are TEM images of the product prepared in Example 1. No cobalt nanoparticles were found in the images, and no diffraction rings or bright spots were found in the SAED images, indicating that the cobalt is highly dispersed. Figure 1 k and l are aberration-corrected electron micrographs of the product prepared in Example 1, clearly showing the dispersion of cobalt single atoms. Figure 2 In Example 1, no cobalt-related diffraction peaks were observed in the product, indicating that cobalt atoms were dispersed. This demonstrates that encapsulating nitrogen-containing metal molecules can effectively confine the metal source, thereby promoting cobalt atomic dispersion and yielding a high-load cobalt single-atom catalyst. Figure 3 In the Co 2p XPS spectrum, only Co-N appeared. x The relevant peaks indicate that Co combines with N to form Co-N. x The active site was determined, and 3.92 at% Co-N was calculated. x The content is much higher than that of the unencapsulated product, indicating that the material prepared by encapsulating nitrogen-containing metal molecules has abundant Co-N content. xThe abundance of active sites promotes the oxygen reduction reaction, thus giving the catalyst excellent oxygen reduction catalytic performance. The N1s XPS spectrum shows pyridine nitrogen, pyrrole nitrogen, and Co-N. x By comparing the peaks of graphitic nitrogen and nitrogen oxide, it can be found that the content of pyridine nitrogen increases significantly after encapsulating small molecules. This indicates that providing an external nitrogen source through encapsulation can effectively increase the content of pyridine nitrogen in the product. Studies have shown that pyridine nitrogen is also an important active site in the oxygen reduction reaction. Figure 4 a shows the cyclic voltammetry curves of the product prepared in Example 1 under N2 and O2. It can be seen that there is no oxygen reduction peak in nitrogen, but an oxygen reduction peak appears in oxygen. Figure 4 In the LSV test curve of b, the product prepared in Example 1 has a half-wave potential of 0.88V and a wavelength of 6mA·cm⁻¹. -2 The limiting diffusion current density exceeds that of the Pt / C catalyst. This was achieved through... Figure 4 Plotting the data from the LSV curves at different speeds in c yields the following results. Figure 4 The KL curve for d shows that the electron transfer number is between 3.7 and 3.79, and this is further confirmed by RRDE testing. Figure 4 The electron transfer number in e is also around 3.8, demonstrating that the material exhibits good four-electron selectivity. These results indicate that encapsulating nitrogen-containing metal molecules can yield cobalt-based single-atom catalysts with excellent oxygen reduction catalytic performance. This is mainly due to the large amount of Co-N generated during the encapsulation of nitrogen-containing metal molecules. x Active sites and high pyridine nitrogen content.
[0040] Example 2
[0041] (1) Mix anhydrous methanol and deionized water in a volume ratio of 1:1.5 to obtain a mixed solvent.
[0042] (2) Dissolve 2.818 g of Zn(NO)3·6H2O, 0.153 g of Co(NO)3·6H2O, and 0.4 g of [Co(en)3]Cl3·3H2O in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 8 min to obtain solution A. Dissolve 8.21 g of 2-methylimidazole and 7 g of PVP in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 8 min to obtain solution B.
[0043] (3) Pour solution A into solution B and stir at room temperature for 40 min. Then place the mixture in a 40℃ oven for constant temperature aging for 36 h. After centrifuging the product, wash it three times with the mixed solvent and then dry it in a 60℃ oven overnight.
[0044] (4) The obtained precursor was placed in a nitrogen atmosphere at 2℃·min -1The temperature was increased to 800℃ at a heating rate, held for 4 hours, and then automatically cooled to obtain the product. ICP-OES characterization showed that the catalyst had a cobalt single-atom loading of 4.05 wt%.
[0045] Due to the prolonged self-assembly reaction time of the reactants, followed by a prolonged aging time, the MOF particle edges are sharper in the SEM image of the precursor prepared in Example 2. While some fragmentation occurred after carbonization, a large specific surface area was still present, allowing for the full exposure of single-atom active sites. This indicates that 800℃ can effectively graphitize the product and promote Co-N... x The formation of active sites resulted in the product prepared in Example 2 having a half-wave potential of 0.87 V and a half-wave potential of 5.9 mA cm⁻¹. -2 The limiting diffusion current density.
[0046] Example 3
[0047] (1) Mix anhydrous methanol and deionized water in a volume ratio of 1:2 to obtain a mixed solvent.
[0048] (2) Dissolve 2.818 g of Zn(NO)3·6H2O, 0.153 g of Co(NO)3·6H2O, and 0.4 g of [Co(en)3]Cl3·3H2O in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 12 min to obtain solution A. Dissolve 8.21 g of 2-methylimidazole and 7 g of PVP in 55 mL of mixed solvent, disperse by ultrasonication, and stir for 12 min to obtain solution B.
[0049] (3) Pour solution A into solution B, stir at room temperature for 20 min, and then place the mixture in an 80℃ oven for constant temperature aging for 12 h. Then centrifuge the product and wash it three times with the mixed solvent, and then dry it in a 60℃ oven overnight.
[0050] (4) The obtained precursor was placed in a nitrogen atmosphere at 2℃·min -1 The temperature was increased to 1000℃ at a heating rate, held for 2 hours, and then automatically cooled to obtain the product. ICP-OES characterization showed that the catalyst had a cobalt single-atom loading of 4.08 wt%.
[0051] As the self-assembly time decreased, the aging temperature increased, and the aging time decreased, the precursor edges of the product in Example 3 became blurred in the SEM image. After carbonization, the morphology of the precursor was well maintained. No obvious cobalt nanoparticles were found in the TEM image, and no diffraction peaks related to cobalt crystal particles were detected in the XRD spectrum, indicating that cobalt exists in a highly dispersed state. High dispersion ensures sufficient exposure of cobalt active sites, which is beneficial for the ORR reaction. Therefore, the product prepared in Example 3 exhibits good electrochemical performance, with a half-wave potential of 0.87 V and a limiting diffusion current density of 5.8 mA cm⁻¹. -2 .
[0052] Comparative Example 1
[0053] [Co(en)3]Cl3·3H2O was not added, and the amount of Co(NO)3·6H2O was changed to 0.4442g. Other conditions were the same as in Example 1.
[0054] Figure 1 g and Figure 1 h is a TEM image of the product prepared in Comparative Example 1. The image clearly shows cobalt nanoparticles in... Figure 2 The presence of diffraction peaks related to the (111), (200), and (220) crystal planes of cobalt indicates the formation of cobalt nanoparticles. The Co 2p XPS spectrum of the product prepared in Comparative Example 1 also shows diffraction peaks related to Co. 0 The relevant peaks are consistent with the TEM and XRD results. These results indicate that when the cobalt source is introduced solely through the ZIF framework without encapsulation technology, severe aggregation of cobalt atoms occurs, directly leading to Co-N... x The number of active sites decreases sharply, thereby reducing the oxygen reduction catalytic performance of the catalyst. Figure 4 In the LSV test curve of b, the product prepared in Comparative Example 1 has only a half-wave potential of 0.84 V and a half-wave potential of 4.66 mA·cm⁻¹. -2 The limiting diffusion current density is lower than that of the Pt / C catalyst and the product prepared in Example 1.
[0055] Comparative Example 2
[0056] Without adding [Co(en)3]Cl3·3H2O and Co(NO)3·6H2O, the other conditions were the same as in Example 1.
[0057] Since no cobalt source was added, and the Zn added to the precursor sublimated during pyrolysis, the product prepared in Comparative Example 2 contained no metals and was a nitrogen-doped carbon material. Figure 2In the first example, only two diffraction peaks belonging to the C(002) and C(101) crystal planes appear around 24° and 44°, respectively. In the second example, there are no metal-related active sites; only carbon defects caused by nitrogen doping serve as oxygen reduction active sites, resulting in extremely poor oxygen reduction activity.
[0058] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.
Claims
1. A method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction, characterized in that, During the self-assembly reaction of dimethylimidazole with zinc nitrate and cobalt nitrate to form ZnCo-ZIF, nitrogen-rich metal molecule tris(ethylenediamine)cobalt(III) chloride trihydrate is introduced, encapsulating the small molecule into the cage structure of ZIF, effectively preventing the aggregation of metal atoms during pyrolysis. After high-temperature carbonization, a cobalt-based single-atom catalyst is obtained. Specifically, the following steps are included: (1) Mix anhydrous methanol and deionized water to obtain a mixed solvent; (2) Dissolve zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and tri(ethylenediamine)cobalt(III) chloride trihydrate in the mixed solvent obtained in step (1) and stir at room temperature. This solution is denoted as solution A. Dissolve dimethylimidazole and polyvinylpyrrolidone in the mixed solvent obtained in step (1) and stir at room temperature. This solution is denoted as solution B. (3) Pour solution A into solution B and stir at room temperature. Place it in an oven for aging treatment, then centrifuge and wash, and dry in an oven. (4) The dried sample is placed in a tube furnace and subjected to high-temperature pyrolysis under a nitrogen atmosphere to obtain the final product.
2. The method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 1, characterized in that, The cobalt-based single-atom catalyst has a cobalt single-atom loading of 4.03~4.08 wt%.
3. A method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 1 or 2, characterized in that, Includes the following steps: (1) Mix anhydrous methanol and deionized water in a volume ratio of 1:1.5~2 to obtain a mixed solvent; (2) Dissolve zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and tri(ethylenediamine)cobalt(III) chloride trihydrate in the mixed solvent obtained in step (1) and stir at room temperature for 8-12 min, and record as solution A; dissolve dimethylimidazole and polyvinylpyrrolidone in the mixed solvent obtained in step (1) and stir at room temperature for 8-12 min, and record as solution B; the molar ratio of cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole is 1:18:190, the amount of tri(ethylenediamine)cobalt(III) chloride trihydrate added in every 55 ml of solution A is 1 mmol, and the amount of polyvinylpyrrolidone added in every 55 ml of solution B is 7 g; (3) Pour solution A into solution B and stir at room temperature for 20-40 minutes. Then, put it into an oven for aging treatment, followed by centrifugal washing and drying in the oven. The aging temperature of the oven is 40-80℃ and the time is 12-36 hours. (4) Place the dried sample into a tube furnace and pyrolyze it at 800~1000℃ for 2~4h under a nitrogen atmosphere to obtain the final product.
4. The method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 3, characterized in that, In step (1), the volume ratio of anhydrous methanol to deionized water in the mixed solvent is 1:1.
75.
5. The method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 3, characterized in that, After stirring for 10 minutes, solution A is added to solution B, and stirring continues for 30 minutes.
6. The method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 3, characterized in that, The aging temperature in the oven is 60℃, and the time is 24 hours.
7. The method for preparing a high-loading cobalt-based single-atom catalyst for oxygen reduction according to claim 3, characterized in that, The pyrolysis treatment was carried out at a temperature of 900℃ for 3 hours.
8. A high-loading cobalt-based single-atom catalyst for oxygen reduction, characterized in that, It is prepared by the method described in any one of claims 1-7.