LU603663B1

LU603663B1 - Carbon-based catalyst doped with dual metal active sites, and preparation method and applications thereof

Info

Publication number: LU603663B1
Application number: LU603663A
Authority: LU
Inventors: Haifeng Chen; Hongdian Chen; Rong Jin; Chaozhong Guo; Wenli Liao; Yao Liu
Original assignee: Univ Chongqing Arts & Sciences
Priority date: 2024-07-19
Filing date: 2024-10-08
Publication date: 2026-03-02
Also published as: WO2026016304A1; CN118782812A; CN118782812B

Abstract

A carbon-based catalyst doped with dual metal active sites, ZnMn-N-C, wherein 1H- 1,2,3-triazole, manganese nitrate, and zinc chloride are used as reaction raw materials to undergo a solvothermal reaction and drying to obtain an Mn-MET-ZnCl₂ powder, which is then sequentially subjected to a first pyrolysis, a sulfuric acid treatment, and a second pyrolysis to afford the ZnMn-N-C catalyst. The ZnMn-N-C prepared in the present disclosure forms a hierarchical pore-channel structure in which numerous micropores are uniformly distributed within mesopores, thereby addressing the pore-structure collapse encountered during formation of such structures. The obtained dual metal active site doped carbon-based catalyst ZnMn-N-C has a high specific surface area of 1837.9 m²/g and an E1/2 = 0.867 V vs. RHE. When used as a cathodic oxygen reduction catalyst to assemble a -1 primary zinc-air battery, an energy density of 889 Wh·kgZn is achieved.

Description

DESCRIPTION LU603663

CARBON-BASED CATALYST DOPED WITH DUAL METAL ACTIVE SITES, AND

PREPARATION METHOD AND APPLICATIONS THEREOF

TECHNICAL FIELD

[0001] The present disclosure relates to the field of electrochemical catalysts, in particular to a carbon-based catalyst doped with dual metal sites and applications thereof.

BACKGROUND

[0002] With intensive research into reducing or replacing platinum-based catalysts in fuel cells with non-precious metals, carbon-based catalysts have become a preferred route for developing high-performance non-platinum oxygen reduction reaction (ORR) electrocatalysts due to their excellent electrical conductivity, stability, and porous structures.

Emerging transition-metal iron-nitrogen-doped carbon-based single-atom catalysts (Fe-N-C

SACs) exhibit unique structures and high catalytic activity and have become a major focus.

However, a pronounced Fenton reaction leads to deteriorated stability and reduces the performance and safety of electrochemical energy-conversion devices. In contrast, Mn/Zn-

N-C exhibits intrinsic ORR activity comparable to that of Fe-N-C, while the Fenton reaction is negligible. Therefore, preparing non-iron-based oxygen reduction catalysts having a large number of accessible active sites is a feasible solution for replacing Pt-based catalysts.

[0003] At present, preparation of Mn/Zn-N-C composite materials typically involves first forming a microporous precursor from a zinc salt and dimethylimidazole, and then creating mesopores within the microporous precursor to obtain an Mn/Zn-N-C composite in which micropores and mesopores coexist.

The microporous structure can increase the adsorption amounts of Zn and Mn, wherea$ 693663 the mesoporous structure exposes more catalytic active sites; the two act synergistically, thereby improving catalytic activity. However, forming mesopores on the basis of preformed micropores is achieved at the expense of the microporous structure. As more mesopores are generated by such a process route, the microporous structure correspondingly decreases sharply, and the overall performance is not ideal.

SUMMARY

[0004] The purpose of the present disclosure is to provide a preparation method for a carbon-based catalyst doped with dual metal active sites. In the method, mesopores are formed first and micropores are formed thereafter, so as to obtain a dual metal sites doped carbon-based catalyst in which mesopores and micropores coexist in a richer manner, thereby effectively improving the catalytic activity of the catalyst.

[0005] Another purpose of the present disclosure is to provide the above dual metal site doped carbon-based catalyst prepared by the method.

[0006] The objectives of the present disclosure are achieved by the following technical solution:

[0007] A carbon based catalyst doped with dual metal active sites, specifically a ZnMn-N-C catalyst, characterized in that 1H-1,2,3 triazole, manganese nitrate, and zinc chloride are used as reactants to undergo a solvothermal reaction and drying to obtain an Mn-MET-

ZnCl, powder, which is then subjected sequentially to a first pyrolysis, sulfuric acid treatment, and a second pyrolysis to afford the ZnMn-N-C catalyst. The interior of the catalyst comprises mesopores, and micropores are further distributed within the mesopores to form a hierarchical pore channel structure.

[0008] Further, the manganese nitrate is prepared as an aqueous solution having a mass concentration of 45~55%, and the dosage ratio of 1H-1,2,3-triazole, the manganese nitrate aqueous solution, and zinc chloride is 300-400 uL: 200-300 JL: 1-2 g.

[0009] Further, the solvothermal reaction is carried out at 80-120 °C, and the reaction time 603663 is 12~48 h.

[0010] Further, the first pyrolysis comprises heating at a rate of 3~5 °C/min to 400-500 °C and holding for 30~40 min, followed by heating at the same rate to 800~1000 °C and holding for 1~2 h.

[0011] Further, the sulfuric acid treatment comprises placing the product obtained from the first pyrolysis into a sulfuric acid solution having a concentration of 0.5~1 mol/L, stirring at 60~80 °C for 10~12 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc or manganese single-atom carbon-based oxygen reduction catalyst.

[0012] Further, the second pyrolysis is performed under an argon atmosphere at 800~1000 °C, and the pyrolysis time is 1~2 h.

[0013] A method for preparing a carbon-based catalyst doped with dual metal active sites, characterized in that 1H-1,2,3-triazole, manganese nitrate, and zinc chloride are used as reactants to undergo a solvothermal reaction and drying to obtain an Mn-MET-ZnCl; powder, which is then subjected sequentially to a first pyrolysis, sulfuric acid treatment, and a second pyrolysis to obtain the ZnMn-N-C catalyst.

[0014] Further, the manganese nitrate is prepared as an aqueous solution having a mass concentration of 45~55%, and the dosage ratio of 1H-1,2,3-triazole, the manganese nitrate aqueous solution, and zinc chloride is 300-400 uL: 200-300 JL: 1-2 g.

[0015] Further, the solvothermal reaction is carried out at 80-120 °C, and the reaction time is 12~48 h.

[0016] Further, the first pyrolysis comprises heating at a rate of 3~5 °C/min to 400-500 °C and holding for 30~40 min, followed by heating at the same rate to 800~1000 °C and holding for 1~2 h.

[0017]In the present disclosure, a mesoporous structure is intended to be formed first, and micropores are then further created within the mesopores to form a nested pore structure in which micropores are distributed within mesopores. Compared with the prior art in which mesopores cover and replace micropores, the approach provides a higher specific surface area and a richer pore architecture, thereby achieving a dual improvement in both the adsorption amount of metal ions and the number of surface-exposed active sites.

[0018] However, in practical preparation, since a large number of mesopores are first,503663 constructed and micropores are then formed within the mesopores, the pore-forming process is difficult to control. Generating many mesopores followed by further activation and modification of the mesoporous structure to form micropores can lead to severe collapse of the material structure, resulting in a dramatic decrease in catalytic performance.

[0019]In view of this, in the present disclosure an Mn-MET-ZnCl, powder is produced by solvothermal reaction of 1H-1,2 3-triazole, manganese nitrate, and an excess amount of zinc chloride. A segmented heating pyrolysis is adopted. During the first heating stage,

MET undergoes slow thermal decomposition at a relatively low temperature to generate a large number of uniformly distributed mesopores. During this process, the excess zinc chloride gradually forms a molten state. When the temperature rises to the second pyrolysis stage, the molten zinc chloride sufficiently etches the metal organic framework material to form pores, thereby generating uniformly distributed micropores within the mesopores and enabling a hierarchical porous structure with a high specific surface area.

During pore formation, the high specific surface area and the hierarchical structure in which micropores are distributed within mesopores enable the Zn and Mn metals that are prone to agglomeration to be anchored as single-atoms on the carbon skeleton at nitrogen defect sites. The contents of single-atom Zn and Mn are further increased while more active sites are exposed, thereby enhancing ORR activity. In addition, the degree of graphitization of the overall carbon material is increased. An increased degree of graphitization assists in improving current density and enhances the stability of the carbon material. The synergistic effect of the high specific surface area hierarchical pores and the single-atom sites is favorable for improving the catalytic activity of the catalyst and the performance of batteries.

[0020] Further, the sulfuric acid treatment comprises placing the product obtained from the first pyrolysis into a sulfuric acid solution having a concentration of 0.5~1 mol/L, stirring at 60~80 °C for 10~12 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc or manganese single-atom carbon-based oxygen reduction catalyst.

[0021] Further, the second pyrolysis is performed under an argon atmosphere at 800~1000 °C, and the pyrolysis time is 1~2 h.

[0022] By means of the second stepwise pyrolysis, the carbon framework structure {S 693663 consolidated, so that the carbon structure that includes micropores within mesopores becomes more robust.

[0023] A method for preparing the above-mentioned carbon-based catalyst doped with dual metal active sites, characterized in that it comprises the following steps:

[0024] (1) Adding 600-800 pL of 1H-1,2,3-triazole, 400-600 pL of a manganese nitrate aqueous solution having a mass concentration of 50%, and 2~4 g of ZnCl, into 30~70 mL of N, N-dimethylformamide and ultrasonically mixing to homogeneity, followed by transferring to an isothermal condition at 80~120 °C for a solvothermal reaction for 12~24 h;

[0025] (2) Upon completion of the reaction, centrifuging, and then drying in a constant- temperature oven at 60-80 °C to obtain an Mn-MET-ZnCl, powder;

[0026](3) Placing the dried Mn-MET-ZnCl, powder obtained in step (2) into an agate mortar and grinding uniformly, then performing a first pyrolysis, which comprises heating at a rate of 3~5 °C/min to 400~500 °C and holding for 30~40 min, followed by heating at the same rate to 800-1000 °C and holding for 1~2 h;

[0027](4) placing the product after the first pyrolysis into a sulfuric acid solution having a concentration of 0.5~1 mol/L, stirring at 60~80 °C for 10~12 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc or manganese single-atom carbon-based oxygen reduction catalyst;

[0028] (5) Transferring the primary zinc or manganese single-atom carbon-based oxygen reduction catalyst into a tube furnace filled with argon, performing a second pyrolysis at 800~1000 °C for 1~2 h to obtain the ZnMn-N-C catalyst, which is the carbon-based catalyst doped with dual metal active sites.

[0029] The application of the above ZnMn-N-C catalyst is specifically in the preparation of zinc-air batteries.

[0030] Further, the above ZnMn-N-C catalyst is applied in the preparation of primary zinc- air batteries.

[0031] Further, the above ZnMn-N-C catalyst is applied in the preparation of rechargeable zinc-air batteries.

[0032]In the ZnMn-N-C catalyst prepared in the present disclosure, which has 12603663 hierarchical pore structure with abundant mesopores and uniformly distributed micropores within the mesopores, the abundant mesoporous structure serves to transport solutes and oxygen in the battery electrode material, while the micropores distributed inside effectively anchor additional single-atom Zn and Mn, further enhancing its ORR activity and thereby improving the energy density and long-term stability of the battery.

[0033] The present disclosure has the following technical effects:

[0034] In the present disclosure, 1H-1,2,3-triazole and zinc chloride are used as porogens for mesopores and micropores, respectively. By regulating the pore-forming sequence and controlling the pore-forming process through pyrolysis, a hierarchical pore-channel structure is formed, thereby solving the problem of pore-structure collapse encountered in forming such a structure. The obtained carbon-based catalyst doped with dual metal sites,

ZnMn-N-C, has a high specific surface area of 1837.9 m?/g and exhibits excellent ORR activity with E12 equal to 0.867 V versus RHE. When used as a cathodic oxygen reduction catalyst to assemble a primary zinc-air battery, an energy density of 889 Wh-kg7, is achieved.

[0035] The present disclosure will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS LU603663

[0036]A more detailed description of the exemplary embodiments of the present disclosure, with reference to the accompanying drawings, will make the above and other objectives, features, and advantages of the present disclosure more apparent. In the exemplary embodiments of the present disclosure, the same reference numerals generally represent the same components.

[0037]FIG. 1: SEM image of the ZnMn-N-C catalyst prepared in Example 3 of the present disclosure.

[0038]FIG. 2: TEM image of the ZnMn-N-C catalyst prepared in Example 3 of the present disclosure.

[0039]FIG. 3: High-resolution transmission electron microscopy (HR-TEM) image of the

ZnMn-N-C catalyst prepared in Example 3 of the present disclosure.

[0040]FIG. 4: High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of the ZnMn-N-C catalyst prepared in Example 3 of the present disclosure.

[0041]FIG. 5: XRD pattern of the ZnMn-N-C catalyst prepared in Example 3 of the present disclosure.

[0042] FIG. 6: N2 adsorption-desorption isotherms of the ZnMn-N-C catalyst prepared in

Example 3 of the present disclosure (inset shows pore distribution).

[0043]FIG. 7: Comparative ORR LSV curves of the ZnMn-N-C catalyst prepared in the present disclosure and a commercial Pt/C catalyst.

[0044]FIG. 8: Comparative ORR LSV curves of the ZnMn-N-C catalyst prepared in the present disclosure and a Pt/C catalyst.

[0045]FIG. 9: Comparison of energy density for primary zinc-air batteries assembled with the ZnMn-N-C catalyst prepared in the present disclosure and with a Pt/C catalyst.

[0046]FIG. 10: Long-term constant current density discharge curve of a primary zinc-aifs03663 battery assembled with the dual-metal-site doped carbon-based catalyst prepared in the present disclosure.

[0047]FIG. 11: Comparative charge/discharge cycling test for rechargeable zinc-air batteries assembled with the ZnMn-N-C catalyst prepared in the present disclosure and with a commercial Pt/C catalyst.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048]Example 1:

[0049]A preparation method for a carbon-based catalyst doped with dual metal active sites, comprising the following steps:

[0050](1) Adding 600 uL of 1H-1,2,3-triazole, 600 UL of a manganese nitrate aqueous solution having a mass concentration of 50%, and 2 g of ZnCl, into 30 mL of N, N- dimethylformamide and ultrasonically mixing to homogeneity, followed by transferring to an isothermal condition at 100 °C for a solvothermal reaction for 18 h;

[0051](2) Upon completion of the reaction, centrifuging, and then drying in a constant- temperature oven at 70 °C to obtain an Mn-MET-ZnCl, powder,

[0052] (3) Placing the dried Mn-MET-ZnCl, powder obtained in step (2) into an agate mortar and grinding uniformly, then performing a first pyrolysis, which comprises heating at a rate of 4 °C/min to 400 °C and holding for 40 min, followed by heating at the same rate to 1000 °C and holding for 1.5 h;

[0053] (4) Placing the product after the first pyrolysis into a sulfuric acid solution having a concentration of 0.8 mol/L and stirring at 70 °C for 12 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc/manganese single-atom carbon-based oxygen reduction catalyst;

[0054] (5) Transferring the primary zinc/manganese single-atom carbon-based oxygen 693663 reduction catalyst into a tube furnace filled with argon, performing a second pyrolysis at 1000 °C for 1 h to obtain the ZnMn-N-C catalyst, which is the carbon-based catalyst doped with dual metal active sites.

[0055] Example 2:

[0056] A preparation method for a carbon-based catalyst doped with dual metal active sites, comprising the following steps:

[0057](1) Adding 800 pL of 1H-1,2,3-triazole, 400 UL of a manganese nitrate aqueous solution having a mass concentration of 50%, and 4 g of ZnCl, into 70 mL of N, N- dimethylformamide and ultrasonically mixing to homogeneity, followed by transferring to an isothermal condition at 80 °C for a solvothermal reaction for 12 h;

[0058] (2) Upon completion of the reaction, centrifuging, and then drying in a constant- temperature oven at 80 °C to obtain an Mn-MET-ZnCl, powder,

[0059](3) Placing the dried Mn-MET-ZnCl, powder obtained in step (2) into an agate mortar and grinding uniformly, then performing a first pyrolysis, which comprises heating at a rate of 3 °C/min to 400 °C and holding for 40 min, followed by heating at the same rate to 1000 °C and holding for 1 h;

[0060] (4) Placing the product after the first pyrolysis into a sulfuric acid solution having a concentration of 1 mol/L and stirring at 60 °C for 10 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc/manganese single-atom carbon-based oxygen reduction catalyst;

[0061](5) Transferring the primary zinc/manganese single-atom carbon-based oxygen reduction catalyst into a tube furnace filled with argon, performing a second pyrolysis at 800 °C for 2 h to obtain the ZnMn-N-C catalyst, which is the carbon-based catalyst doped with dual metal active sites.

[0062] The carbon-based catalyst doped with dual metal sites, ZnMn-N-C, prepared in this

Example has a high specific surface area of 1829.8 m?/g, a Zn/Mn—Ny active-site content of 21.35%, and exhibits excellent ORR activity with E12 = 0.864 V vs. RHE.

[0063] Example 3:

[0064] A preparation method for a carbon-based catalyst doped with dual metal active sité$,503663 comprising the following steps:

[0065](1) Adding 740 UL of 1H-1,2,3-triazole, 585 UL of a manganese nitrate aqueous solution having a mass concentration of 50%, and 3.4 g of ZnCl, into 50 mL of N, N- dimethylformamide and ultrasonically mixing to homogeneity, followed by transferring to an isothermal condition at 120 °C for a solvothermal reaction for 24 h;

[0066] (2) Upon completion of the reaction, centrifuging, and then drying in a constant- temperature oven at 60 °C to obtain an Mn-MET-ZnCl, powder,

[0067](3) Placing the dried Mn-MET-ZnCl, powder obtained in step (2) into an agate mortar and grinding uniformly, then performing a first pyrolysis, which comprises heating at a rate of 5 °C/min to 450 °C and holding for 35 min, followed by heating at the same rate to 900 °C and holding for 2 h;

[0068] (4) Placing the product after the first pyrolysis into a sulfuric acid solution having a concentration of 0.5 mol/L and stirring at 80 °C for 12 h, then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc/manganese single-atom carbon-based oxygen reduction catalyst;

[0069](5) Transferring the primary zinc/manganese single-atom carbon-based oxygen reduction catalyst into a tube furnace filled with argon, performing a second pyrolysis at 900 °C for 1 h to obtain the ZnMn-N-C catalyst, which is the carbon-based catalyst doped with dual metal active sites.

[0070] The carbon-based catalyst doped with dual metal sites, ZnMn-N-C, prepared in

Example 3 has a high specific surface area of 1830.1 m?/g, a Zn/Mn-Nx active-site content of 22.16%, and exhibits excellent ORR activity with E12 = 0.870 V vs. RHE.

[0071]FIG. 1 is the SEM image of the ZnMn-N-C catalyst prepared in Example 3. It can HE 603663 seen that the ZnMn-N-C catalyst exhibits a three-dimensional morphology with a rich porous structure, having abundant mesopores, while a large number of micropores are formed within the mesopores. This benefits from the organic ligand 1H-1,2,3-triazole used to form the metal-organic framework material, which decomposes first during the first pyrolysis to form mesopores, and the excess molten ZnCl, provides a pore-forming capability at higher temperatures to form micropores, thereby achieving a hierarchical pore structure in which micropores are distributed within mesopores. FIG. 2 is the TEM image of the ZnMn-N-C catalyst prepared in this Example, showing the formation of a three- dimensional porous structure.

[0072]FIG. 3 is the HR-TEM image of the ZnMn-N-C catalyst prepared in Example 3.

Irregular lattice fringes indicate that the carbon matrix is amorphous; the selected-area electron diffraction inset also evidences the absence of crystals in the entire carbon matrix, which indicates that metallic Zn/Mn are successfully embedded in the carbon matrix in the form of single-atoms.

[0073]FIG. 4 is the aberration-corrected HAADF-STEM image of the ZnMn-N-C catalyst prepared in Example 3. Individual bright spots directly demonstrate the dispersion of Zn/Mn atoms, evidencing that the synthesized ZnMn-N-C catalyst possesses abundant and uniformly dispersed single-atom Zn/Mn sites.

[0074] As shown in FIG. 5, the X-ray diffraction pattern of the ZnMn-N-C catalyst prepared in Example 3 indicates the absence of crystalline metallic phases.

[0075] To analyze the content of the transition-metal Zn/Mn-Nx active sites, X-ray photoelectron spectroscopy (XPS) was employed. As shown in FIG. 6, the content of

Zn/Mn-Nx active sites reaches as high as 21.83%. The presence of a high content of active sites indicates that endogenously doped excess ZnCl, not only achieved pore formation inside the metal-organic framework material, but also successfully anchored the Mn/Zn metals, which tend to agglomerate, as single-atoms on the defective carbon skeleton.

[0076]FIG. 7 shows that the ZnMn-N-C catalyst prepared in Example 3 presents a typical 503663 type-IV nitrogen adsorption-desorption isotherm. The pore-size distribution indicates that the ZnMn-N-C catalyst has a mesopore-dominated hierarchical porous structure, with a specific surface area as high as 1837.9 m°/g. The interior contains a hierarchical porous structure with numerous micropores, which can accelerate electron transfer and mass transport.

[0077]As shown by the LSV curves in FIG. 8, the catalyst exhibits excellent electrochemical performance. It can be seen that the ZnMn-N-C catalyst prepared in

Example 3 displays superior ORR activity (E12 = 0.867 V vs. RHE, JL = 5.9 mA/cm?) compared with Pt/C (E12 = 0.86 V vs. RHE, JL = 5.81 mA/cm?).

[0078] Comparative Example 1:

[0079] Compared with Example 3, during the first pyrolysis the temperature was directly raised at the same rate to 900 °C and held for 2 h; the remaining steps were the same as in Example 3.

[0080] Because the temperature during the first pyrolysis was directly increased to a relatively high 900 °C, the decomposition of MET intensified with increasing temperature, resulting in poor stability during mesopore formation. During the subsequent holding stage, when excess zinc chloride formed micropores, a large number of mesopores collapsed.

Consequently, a rich mesoporous structure and a hierarchical porous structure of uniformly distributed internal micropores were not formed in the carbon material, and the specific surface area decreased significantly. Testing showed a BET specific surface area of 844.7 m?/g and a Zn/Mn—Nx active-site content of 9.16%.

[0081] Example 4:

[0082] Application of the dual metal site doped carbon-based catalyst (ZnMn-N-C) in the preparation of primary zinc-air batteries and rechargeable zinc-air batteries:

[0083]2 mg of the ZnMn-N-C catalyst prepared in Example 3 was uniformly dispersed in a mixed solution composed of 195 pL ethanol and 5 pL naphthol, and then uniformly coated on 4 cm? carbon cloth as the cathodic oxygen reduction catalyst. A Zn sheet with a thickness of 0.2 mm was selected as the anode, and a 6 mol/L KOH solution was used as the electrolyte to assemble a primary zinc-air battery.

[0084] Control group: a primary zinc-air battery was assembled in the same manner 603663 except that a commercially purchased Pt/C catalyst was used in place of the ZnMn-N-C catalyst prepared in Example 3.

[0085]FIG. 9 shows the comparison of energy density for primary zinc-air batteries assembled with the ZnMn-N-C catalyst prepared in Example 3 and with the commercial

Pt/C catalyst. From the figure it can be seen that, when discharged at a fixed current density of 50 mA/cm?, the primary zinc-air battery assembled with the Mn-N@8Gra-L catalyst exhibits a high energy density of 889 Wh-kg7,, far exceeding the energy density of the primary zinc-air battery assembled with Pt/C (763 Wh-kg;;).

[0086] FIG. 10 shows the long-time discharge of the primary zinc-air battery prepared in

Example 4 at a fixed current density of 50 mA/cm? Under a constant-current-density discharge lasting as long as 150 h, the discharge voltage of the assembled primary zinc-air battery decreases by only 49 mV.

[0087] Example 5:

[0088] Application of the dual-metal-site doped carbon-based catalyst (ZnMn-N-C) in the preparation of rechargeable zinc-air batteries:

[0089]2 mg of the ZnMn-N-C catalyst prepared in Example 3 and 2 mg of RuO, were uniformly dispersed in a mixed solution composed of 390 uL ethanol and 10 pL naphthol, and then uniformly coated on 4 cm? carbon cloth as the cathodic oxygen reduction catalyst.

A Zn sheet with a thickness of 0.2 mm was selected as the anode, and a mixed solution of

KOH and Zn(Ac), was used as the electrolyte to assemble a rechargeable zinc-air battery, wherein the concentration of KOH was 6 mol/L and the concentration of Zn(Ac), was 0.2 mol/L.

[0090] Control group: a rechargeable zinc-air battery was prepared by the same method using a commercial Pt/C catalyst instead of the ZnMn-N-C catalyst prepared in Example 3 for comparison.

[0091] As shown in FIG. 11, during a charge/discharge process lasting more than 100 M U603663 the rechargeable zinc-air battery assembled from the ZnMn-N-C catalyst and RuO, in

Example 5 maintains a discharge voltage of 1.1664 V and a charge voltage of 2.0271 V, with a charge/discharge voltage gap of 86.1 mV, whereas the rechargeable zinc-air battery assembled from Pt/C and RuO, exhibits a larger charge/discharge voltage gap (90 mV), indicating that the application of the ZnMn-N-C catalyst in rechargeable zinc-air batteries affords better long-term cycling stability.

[0092] The foregoing embodiments are only preferred embodiments of the present disclosure, and are not intended to limit the scope of protection of the present disclosure.

Any non-substantive changes and substitutions made by those skilled in the art on the basis of the present disclosure shall fall within the scope of protection claimed by the present disclosure.

Claims

CLAIMS LU603663

1. A carbon-based catalyst doped with dual metal active sites, ZnMn-N-C, wherein 1H- 1,2,3-triazole, manganese nitrate, and zinc chloride are used as reaction raw materials to undergo a solvothermal reaction and drying to obtain an Mn-MET-ZnCl2 powder; the powder is then sequentially subjected to a first pyrolysis, a sulfuric acid treatment, and a second pyrolysis to afford the ZnMn-N-C catalyst; the catalyst has an internal mesoporous distribution, and micropores are further distributed within the mesopores to form a hierarchical pore-channel structure.

2. The carbon-based catalyst doped with dual metal active sites according to claim 1, wherein the manganese nitrate is prepared as an aqueous solution having a mass concentration of 45~55%, and the dosage ratio of 1H-1,2,3-triazole, the manganese nitrate aqueous solution, and zinc chloride is 300-400 uL: 200-300 uL: 1-2 g.

3. The carbon-based catalyst doped with dual metal active sites according to claim 2, wherein the first pyrolysis comprises heating at 3~5 °C/min to 400~500 °C and holding for 30~40 min, followed by heating at the same rate to 800~1000 °C and holding for 1~2 h.

4. A method for preparing a carbon-based catalyst doped with dual metal active sites, wherein 1H-1,2 3-triazole, manganese nitrate, and zinc chloride are used as reaction raw materials to undergo a solvothermal reaction and drying to obtain an Mn-MET-ZnCl, powder, and the powder is then sequentially subjected to a first pyrolysis, a sulfuric acid treatment, and a second pyrolysis.

5. The method according to claim 4, wherein the manganese nitrate is prepared as an aqueous solution having a mass concentration of 45~55%, and the dosage ratio of 1H- 1,2,3-triazole, the manganese nitrate aqueous solution, and zinc chloride is 300-400 pL: 200-300 pL: 1-2 g.

6. The method according to claim 5, wherein the solvothermal reaction temperature |S 6923663 80~120 °C and the reaction time is 12~48 h.

7. The method according to claim 6, wherein the first pyrolysis comprises heating at 3~5 °C/min to 400~500 °C and holding for 30~40 min, followed by heating at the same rate to 800~1000 °C and holding for 1~2 h.

8. The method according to claim 7, wherein the sulfuric acid treatment comprises placing the product obtained from the first pyrolysis into a sulfuric acid solution of 0.5-1 mol/L, stirring at 60-80 °C for 10-12 h, and then washing with ultrapure water, vacuum filtering, and drying to obtain a primary zinc/manganese single-atom carbon-based oxygen reduction catalyst.

9. The method according to claim 8, wherein the second pyrolysis is performed in an argon atmosphere at 800-1000 °C, and the pyrolysis time is 1-2 h.