Preparation method and application of cobalt-nitrogen-doped mesoporous carbon catalyst
By preparing a cobalt-nitrogen-doped mesoporous carbon catalyst with a rod-shaped mesoporous structure, the problems of complex preparation methods and low active site density of existing catalysts have been solved, achieving high-efficiency oxygen reduction reaction performance. In particular, it exhibits excellent catalytic activity and stability under alkaline conditions, making it suitable for large-scale applications.
Patent Information
- Application Number
- CN202510980522.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-10-28
Smart Images
Figure CN120854578A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation technology, and in particular to a method for preparing and applying a cobalt-nitrogen-doped mesoporous carbon catalyst. Background Technology
[0002] In the field of energy conversion and storage, the oxygen reduction reaction (ORR) is a core reaction step in key technologies such as fuel cells and metal-air batteries. While traditional noble metal catalysts (such as platinum-based catalysts) possess excellent catalytic activity, their large-scale application is severely limited by their scarcity, high cost, poor stability, and susceptibility to poisoning by fuels such as methanol. Therefore, developing low-cost, highly active, and stable non-noble metal catalysts has become a research hotspot in this field.
[0003] In recent years, transition metal-nitrogen-carbon (MNC) materials have been considered among the most promising non-noble metal catalysts due to their unique electronic structure and high ORR catalytic activity. However, existing MNC catalyst preparation methods suffer from numerous problems, such as complex preparation processes, difficulty in precisely controlling the catalyst's structure and composition, and low active site density, resulting in overall catalyst performance that fails to meet practical application requirements. Furthermore, how to effectively regulate the mesoporous structure of the catalyst to improve its specific surface area and mass transfer performance, thereby enhancing catalytic activity and stability, remains a key issue that urgently needs to be addressed in this field. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing and applying a cobalt-nitrogen-doped mesoporous carbon catalyst to solve the above-mentioned problems.
[0005] This invention provides a method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, comprising the following steps:
[0006] S1. Preparation of template mesoporous carbon: Glucose and SBA-15 mesoporous molecular sieve are mixed and ground, and then pyrolyzed under nitrogen atmosphere. The product is soaked in hydrofluoric acid to remove the SBA-15 template, and then centrifuged three times with water and ethanol alternately to obtain a precipitate. The precipitate is dried to obtain mesoporous carbon.
[0007] S2. Preparation of Cobalt-Nitrogen Doped Precursor Solution: Dissolve o-phenanthroline and cobalt chloride hexahydrate separately in ethanol and then mix them to form a Co-phen solution;
[0008] S3. Immersion and pyrolysis: The mesoporous carbon obtained in step S1 is immersed in the Co-phen solution in step S2. After immersion, the solvent is evaporated and the carbon is ground into powder. The powder is then heat-treated under a nitrogen atmosphere to obtain a cobalt nitrogen-doped mesoporous carbon catalyst.
[0009] Preferably, in the above-mentioned method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, in step S1, the mass ratio of glucose to SBA-15 is 5:1, the high-temperature pyrolysis temperature is 900℃, the heating rate is 10℃ / min, and the pyrolysis time is 1h.
[0010] Preferably, in the above-mentioned method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, in step S2, the mass ratio of o-phenanthroline to cobalt chloride hexahydrate is 1:2, and the volume of the ethanol solution is 10 mL.
[0011] Preferably, in the above-mentioned method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, in step S3, the soaking time of the mesoporous carbon in the Co-phen solution is 2 hours, the heat treatment temperature is 800-950°C, and the time is 1 hour. The cobalt-nitrogen-doped mesoporous carbon catalyst is named "CN-xCo-T", where x represents the concentration of o-phenanthroline cobalt and T represents the heat treatment temperature.
[0012] Preferably, in the above-mentioned method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, the optimal temperature for heat treatment is 900°C, and the optimal concentration of cobalt o-phenanthroline is 8.
[0013] A cobalt-nitrogen-doped mesoporous carbon catalyst prepared by the method described above has a rod-shaped mesoporous structure and a specific surface area of 739.17 m². 2 / g, with a pore size distribution in the range of 5-20nm, and the active site is a Co-Nx structure.
[0014] The application of the cobalt-nitrogen-doped mesoporous carbon catalyst as described above in the oxygen reduction reaction, wherein the catalyst is used for the oxygen reduction reaction under alkaline conditions.
[0015] Therefore, this invention employs the aforementioned method and application for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst. Through steps such as template mesoporous carbon preparation, cobalt-nitrogen-doped precursor solution preparation, and soaking and pyrolysis, the catalyst's controllable synthesis is achieved. In the template mesoporous carbon preparation process, the use of a mixture of glucose and SBA-15 mesoporous molecular sieve through grinding and pyrolysis allows for precise control of the mesoporous carbon structure. By optimizing the mass ratio of glucose to SBA-15, the pyrolysis temperature, the heating rate, and the pyrolysis time, an ideal mesoporous carbon support can be obtained. In the preparation of the cobalt-nitrogen-doped precursor solution, the appropriate setting of the mass ratio of o-phenanthroline to cobalt chloride hexahydrate and the volume of the ethanol solution lays the foundation for subsequent uniform doping. In the soaking and pyrolysis steps, precise control of the soaking time, heat treatment temperature, and time of the mesoporous carbon and Co-phen solution enables effective cobalt-nitrogen doping and stable catalyst structure construction. Furthermore, this method is simple, easy to operate, and suitable for large-scale production.
[0016] The prepared cobalt-nitrogen-doped mesoporous carbon catalyst has a unique rod-shaped mesoporous structure and a specific surface area as high as 739.17 m². 2 The catalyst has a pore size distribution ranging from 5 to 20 nm. This structural feature provides excellent channels for the diffusion of reactants and products, effectively improving mass transfer efficiency, while the large specific surface area provides more opportunities for the exposure of active sites. Its active sites are Co-Nx structures, which possess excellent electron transport capabilities and adsorption-activation capabilities for oxygen molecules, resulting in high catalytic activity in oxygen reduction reactions. Especially when used in oxygen reduction reactions under alkaline conditions, it can significantly reduce the overpotential, increase the reaction rate and energy conversion efficiency, showing promising application prospects. Further optimization of the heat treatment temperature and the concentration of cobalt o-phenanthroline has enhanced the overall performance of the catalyst, providing a better option for practical applications.
[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0018] Figure 1 The images show SEM images of SBA-15 and CN-8Co-900 catalysts in the preparation method and application examples of the cobalt nitrogen doped mesoporous carbon catalyst of the present invention, wherein (a) is the SEM of SBA-15 and (b) is the SEM of CN-8Co-900.
[0019] Figure 2 The image shows the BET performance of the mesoporous carbon and CN-8Co-900 catalysts in the preparation method and application examples of the cobalt nitrogen doped mesoporous carbon catalyst of the present invention. In the image, (a) is the nitrogen adsorption-desorption isotherm, (b) is the pore size distribution curve, and (c) is the BET specific surface area diagram.
[0020] Figure 3 The CV curves of CN-4Co-900, CN-8Co-900, CN-16Co-900, CN-8Co-800, and CN-8Co-950 catalysts, which are cobalt nitrogen doped mesoporous carbon catalysts according to the preparation method and application examples of the present invention, under 0.1M KOH saturated O2 and N2 conditions;
[0021] Figure 4 The LSV curves and half-wave potential diagrams of CN-4Co-900, CN-8Co-900, CN-16Co-900, CN-8Co-800, CN-8Co-950 catalysts and Pt / C catalysts are shown in the present invention for the preparation method and application examples of a cobalt nitrogen doped mesoporous carbon catalyst. (a) is the LSV curve of the catalyst and (b) is the half-wave potential of the catalyst.
[0022] Figure 5 This is a schematic diagram showing the RRDE test, hydrogen peroxide yield, and number of transferred electrons of CN-4Co-900, CN-8Co-900, CN-16Co-900, CN-8Co-800, and CN-8Co-950 catalysts, which are preparation methods and application examples of cobalt nitrogen doped mesoporous carbon catalysts of the present invention. (a) shows the RRDE test of the catalyst, and (b) shows the hydrogen peroxide yield and number of transferred electrons of the catalyst.
[0023] Figure 6 This diagram illustrates the methanol tolerance and stability test results of CN-8Co-900 and Pt / C catalysts in the preparation method and application examples of the cobalt-nitrogen-doped mesoporous carbon catalyst of the present invention. (a) shows the methanol tolerance test, and (b) shows the stability test. Detailed Implementation
[0024] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0025] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.
[0026] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.
[0027] This invention provides a method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, comprising the following steps:
[0028] S1. Preparation of template mesoporous carbon: Glucose and SBA-15 mesoporous molecular sieve are mixed and ground, and then pyrolyzed under nitrogen atmosphere. The product is soaked in hydrofluoric acid to remove the SBA-15 template, and then centrifuged three times with water and ethanol alternately to obtain a precipitate. The precipitate is dried to obtain mesoporous carbon.
[0029] S2. Preparation of Cobalt-Nitrogen Doped Precursor Solution: Dissolve o-phenanthroline and cobalt chloride hexahydrate separately in ethanol and then mix them to form a Co-phen solution;
[0030] S3. Immersion and pyrolysis: The mesoporous carbon obtained in step S1 is immersed in the Co-phen solution in step S2. After immersion, the solvent is evaporated and the carbon is ground into powder. The powder is then heat-treated under a nitrogen atmosphere to obtain a cobalt nitrogen-doped mesoporous carbon catalyst.
[0031] To further optimize the above technical solution, in step S1, the mass ratio of glucose to SBA-15 is 5:1, the temperature of the high-temperature pyrolysis is 900℃, the heating rate is 10℃ / min, and the pyrolysis time is 1h.
[0032] To further optimize the above technical solution, in step S2, the mass ratio of o-phenanthroline to cobalt chloride hexahydrate is 1:2, and the volume of the ethanol solution is 10 mL.
[0033] To further optimize the above technical solution, in step S3, the soaking time of the mesoporous carbon and Co-phen solution is 2 hours, the heat treatment temperature is 800-950℃ and the time is 1 hour, and the cobalt nitrogen doped mesoporous carbon catalyst is named "CN-xCo-T", where x represents the concentration of o-phenanthroline cobalt and T represents the heat treatment temperature.
[0034] To further optimize the above technical solution, the optimal temperature for heat treatment is 900℃, and the optimal concentration of cobalt o-phenanthroline is 8.
[0035] A cobalt-nitrogen-doped mesoporous carbon catalyst prepared by the method described above has a rod-shaped mesoporous structure and a specific surface area of 739.17 m². 2 / g, with a pore size distribution in the range of 5-20nm, and the active site is a Co-Nx structure.
[0036] The application of the cobalt-nitrogen-doped mesoporous carbon catalyst in the oxygen reduction reaction, as described above, is that the catalyst is used for the oxygen reduction reaction under alkaline conditions.
[0037] To more clearly and in detail introduce the preparation method and application of a cobalt-nitrogen-doped mesoporous carbon catalyst provided by the embodiments of the present invention, the following description will be based on specific embodiments.
[0038] Example 1
[0039] Preparation and performance verification of CN-8Co-900 catalyst
[0040] S1. Preparation of template mesoporous carbon: 1.5g glucose and 0.3g SBA-15 mesoporous molecular sieve were mixed and ground at a mass ratio of 5:1 for 30min. The mixture was then transferred to a tube furnace and pyrolyzed at 900℃ for 1h under a nitrogen atmosphere at a rate of 10℃ / min. After detemplating with hydrofluoric acid, the mixture was centrifuged three times alternately with water and ethanol, and then vacuum dried at 80℃ to obtain mesoporous carbon.
[0041] S2. Preparation of Cobalt Nitrogen Precursor Solution: Dissolve 76 mg of o-phenanthroline and 176 mg of cobalt chloride hexahydrate in ethanol at a mass ratio of 1:2, then mix to form 10 mL of Co-phen solution.
[0042] S3. Immersion and pyrolysis: 1.0 g of mesoporous carbon was immersed in Co-phen solution for 2 h, the solvent was evaporated and then ground. The mixture was then heat-treated at 900 °C for 1 h under a nitrogen atmosphere to obtain CN-8Co-900 catalyst.
[0043] The obtained catalyst was subjected to mesoporous structure study and morphological characterization.
[0044] like Figure 1 As shown, SEM images verify that CN-8Co-900 completely replicates the rod-shaped mesoporous structure of the SBA-15 template, demonstrating the morphology preservation capability of the template-induced process. Figure 2 As shown, BET and pore size analysis revealed that the nitrogen adsorption-desorption isotherm of CN-8Co-900 is type IV, with a pore size distribution concentrated in the 5-20 nm range and a specific surface area of 739.17 m². 2 / g, verifying the formation of high specific surface area mesoporous structures.
[0045] Example 2
[0046] Effect of heat treatment temperature on catalyst performance
[0047] Compared with Example 1, CN-8Co-800 was obtained by changing the heat treatment temperature of step S3 to 800℃ for 1 hour while keeping the other conditions unchanged. CN-8Co-950 was obtained by changing the heat treatment temperature of step S3 to 950℃ for 1 hour while keeping the other conditions unchanged.
[0048] Example 3
[0049] Effect of cobalt o-phenanthroline concentration on catalyst performance
[0050] Compared with Example 1, the precursor concentration in step S2 was modified to 38 mg o-phenanthroline and 88 mg cobalt chloride hexahydrate (x = 4), while the other conditions remained unchanged to obtain CN-4Co-900; the precursor concentration in step S2 was modified to 152 mg o-phenanthroline and 352 mg cobalt chloride hexahydrate (x = 16), while the other conditions remained unchanged to obtain CN-16Co-900;
[0051] Comparative Example 1
[0052] The comparison samples were CN-8Co-900 catalyst and commercial Pt / C catalyst.
[0053] CN-8Co-900 catalyst: prepared according to the method of Example 1, that is, glucose and SBA-15 in a mass ratio of 5:1, template pyrolyzed at 900℃, and precursor solution prepared by o-phenanthroline and cobalt chloride hexahydrate in a mass ratio of 1:2, soaked and then heat-treated at 900℃ for 1h.
[0054] Commercial Pt / C catalyst: 20% Pt loading (Johnson Matthey, UK), model JM-20Pt / C.
[0055] To verify the catalyst performance, CV curve analysis, LSV testing, RRDE testing, and methanol tolerance and stability testing were performed on the catalysts obtained in Examples 1-3 and the commercial Pt / C catalyst of Comparative Example 1, as detailed below:
[0056] To further evaluate the oxygen reduction reaction (ORR) activity of the catalyst, the electrochemical performance of the prepared catalyst was further tested using cyclic voltammetry (CV) under alkaline conditions. Figure 3 It is evident that in an oxygen-saturated electrolyte system, the CV curves of the five catalysts—CN-4Co-900, CN-8Co-800, CN-8Co-900, CN-8Co-950, and CN-16Co-900—all exhibit redox peaks, indicating good electrocatalytic performance. Further analysis of these five catalysts revealed that at 900℃, the peak values for CN-4Co-900, CN-8Co-900, and CN-16Co-900 catalysts were 0.813V, 0.873V, and 0.833V (vs RHE), respectively. This demonstrates that, at the same temperature, the CN-8Co-900 catalyst exhibits the best ORR performance. Further analysis revealed differences in the oxygen reduction activity of catalysts prepared at different heat treatment temperatures. Observations showed that the peak values of CN-8Co-800, CN-8Co-900, and CN-8Co-950 catalysts were 0.843V, 0.873V, and 0.803V (vsRHE), respectively. This demonstrates that at a temperature of 900℃, the CN-8Co-900 catalyst exhibits higher ORR performance.
[0057] Further electrochemical activity tests of the catalyst were conducted under alkaline conditions using a rotating disk electrode. Figure 4 Linear sweep voltammetry (LSV) curves and half-wave potential diagrams were obtained for the preparation of the catalyst. Figure 4As shown in (a), the electrocatalytic performance of all catalysts first increases and then decreases with the change of catalyst concentration. Figure 4 In (b), the half-wave potentials (E1 / 2) of CN-2Co-900, CN-4Co-900, CN-8Co-900, CN-16Co-900, CN-32Co-900, and Pt / C catalysts were 0.813V, 0.848V, 0.873V, 0.843V, 0.833V, and 0.85V (vs. RHE), respectively. Numerical comparison revealed that the CN-8Co-900 catalyst had the highest half-wave potential (E1 / 2), indicating that at the same temperature of 900℃, the CN-8Co-900 catalyst exhibited the best ORR performance. In terms of electrocatalytic activity, the CN-8Co-900 catalyst also outperformed the Pt / C catalyst. Figure 4 As shown, LSV testing was conducted, and the results showed that the half-wave potential of CN-8Co-900 was 0.873V, which exceeded the 0.85V of commercial Pt / C catalysts, and the peak current density was the highest, verifying its superior catalytic activity.
[0058] The oxygen reduction pathway was analyzed using a rotating ring-disk electrode (RRDE) system, such as... Figure 5 As shown, the H2O2 yields of CN-4Co-900, CN-8Co-800, CN-8Co-900, CN-8Co-950, and CN-16Co-900 catalysts are all below 20%, with the H2O2 yield of CN-8Co-900 catalyst being around 10%, and close to the 4-electron transfer pathway.
[0059] To systematically evaluate the long-term stability of the oxygen reduction reaction (ORR) of the CN-8Co-900 catalyst, the CN-8Co-900 catalyst was compared with a Pt / C catalyst, and a current response test was continuously performed for 20,000 s. Figure 6 As shown in (b), after a period of testing, the activity of the noble metal platinum-based catalyst (Pt / C) decreased by as much as 19.8%, while the activity of the CN-8Co-900 catalyst decreased by only 8%, demonstrating significantly better stability parameters than the Pt / C catalyst. Figure 6 (a) Observation of the it curve shows that in the methanol interference test, the current fluctuation of CN-8Co-900 catalyst is not obvious, while the current of platinum-based catalyst decreases significantly within 100s, indicating that CN-8Co-900 catalyst has excellent resistance to methanol poisoning.
[0060] Therefore, this invention employs the aforementioned method and application for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst. Through steps such as template mesoporous carbon preparation, cobalt-nitrogen-doped precursor solution preparation, and soaking and pyrolysis, the catalyst's controllable synthesis is achieved. In the template mesoporous carbon preparation process, the use of a mixture of glucose and SBA-15 mesoporous molecular sieve through grinding and pyrolysis allows for precise control of the mesoporous carbon structure. By optimizing the mass ratio of glucose to SBA-15, the pyrolysis temperature, the heating rate, and the pyrolysis time, an ideal mesoporous carbon support can be obtained. In the preparation of the cobalt-nitrogen-doped precursor solution, the appropriate setting of the mass ratio of o-phenanthroline to cobalt chloride hexahydrate and the volume of the ethanol solution lays the foundation for subsequent uniform doping. In the soaking and pyrolysis steps, precise control of the soaking time, heat treatment temperature, and time of the mesoporous carbon and Co-phen solution enables effective cobalt-nitrogen doping and stable catalyst structure construction. Furthermore, this method is simple, easy to operate, and suitable for large-scale production.
[0061] The prepared cobalt-nitrogen-doped mesoporous carbon catalyst has a unique rod-shaped mesoporous structure and a specific surface area as high as 739.17 m². 2 The catalyst has a pore size distribution ranging from 5 to 20 nm. This structural feature provides excellent channels for the diffusion of reactants and products, effectively improving mass transfer efficiency, while the large specific surface area provides more opportunities for the exposure of active sites. Its active sites are Co-Nx structures, which possess excellent electron transport capabilities and adsorption-activation capabilities for oxygen molecules, resulting in high catalytic activity in oxygen reduction reactions. Especially when used in oxygen reduction reactions under alkaline conditions, it can significantly reduce the overpotential, increase the reaction rate and energy conversion efficiency, showing promising application prospects. Further optimization of the heat treatment temperature and the concentration of cobalt o-phenanthroline has enhanced the overall performance of the catalyst, providing a better option for practical applications.
[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst, characterized in that, Includes the following steps: S1. Preparation of template mesoporous carbon: Glucose and SBA-15 mesoporous molecular sieve are mixed and ground, and then pyrolyzed under nitrogen atmosphere. The product is soaked in hydrofluoric acid to remove the SBA-15 template, and then centrifuged three times with water and ethanol alternately to obtain a precipitate. The precipitate is dried to obtain mesoporous carbon. S2. Preparation of Cobalt-Nitrogen Doped Precursor Solution: Dissolve o-phenanthroline and cobalt chloride hexahydrate separately in ethanol and then mix them to form a Co-phen solution; S3. Immersion and pyrolysis: The mesoporous carbon obtained in step S1 is immersed in the Co-phen solution in step S2. After immersion, the solvent is evaporated and the carbon is ground into powder. The powder is then heat-treated under a nitrogen atmosphere to obtain a cobalt nitrogen-doped mesoporous carbon catalyst.
2. The method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst according to claim 1, characterized in that, In step S1, the mass ratio of glucose to SBA-15 is 5:1, the high-temperature pyrolysis temperature is 900℃, the heating rate is 10℃ / min, and the pyrolysis time is 1h.
3. The method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst according to claim 1, characterized in that, In step S2, the mass ratio of o-phenanthroline to cobalt chloride hexahydrate is 1:2, and the volume of the ethanol solution is 10 mL.
4. The method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst according to claim 1, characterized in that, In step S3, the soaking time of the mesoporous carbon in the Co-phen solution is 2 hours, the heat treatment temperature is 800-950℃ and the time is 1 hour, and the cobalt nitrogen doped mesoporous carbon catalyst is named "CN-xCo-T", where x represents the concentration of o-phenanthroline cobalt and T represents the heat treatment temperature.
5. The method for preparing a cobalt-nitrogen-doped mesoporous carbon catalyst according to claim 4, characterized in that, The optimal temperature for the heat treatment is 900°C, and the optimal concentration of cobalt o-phenanthroline is 8%.
6. A cobalt-nitrogen-doped mesoporous carbon catalyst obtained by the preparation method according to any one of claims 1-5, characterized in that, The catalyst has a rod-shaped mesoporous structure and a specific surface area of 739.17 m². 2 / g, with a pore size distribution in the range of 5-20nm, and the active site is a Co-Nx structure.
7. The application of the cobalt-nitrogen-doped mesoporous carbon catalyst as described in claim 6, characterized in that, The catalyst is used for oxygen reduction reaction under alkaline conditions.