Bimetal site doped carbon-based catalyst, and preparation method therefor and use thereof

Abstract

A bimetal active site doped carbon-based catalyst, which is particularly a ZnMn-N-C catalyst. The ZnMn-N-C catalyst is prepared by using 1H-1,2,3-triazole, manganous nitrate and zinc chloride as reaction raw materials, subjecting same to a solvothermal reaction and then to drying to obtain a Mn-MET-ZnCl2 powder, and then sequentially subjecting the powder to primary pyrolysis, a sulfuric acid treatment and secondary pyrolysis. By respectively using 1H-1,2,3-triazole and zinc chloride as a mesopore forming agent and a micropore forming agent, and adjusting the pore-forming sequence and controlling the pore-forming process by means of pyrolysis, a large number of mesopores are preferentially formed, and then a large number of micropores are uniformly distributed in the mesopores, thereby forming a hierarchical pore channel structure and overcoming the problem of the collapse of the pore channel structure during the formation of the structure; and the obtained bimetal site doped carbon-based catalyst ZnMn-N-C has a high specific surface area of 1837.9 m2 / g and exhibits a good ORR activity (E1 / 2=0.867 V vs. RHE), and a primary zinc-air battery assembled by using the catalyst ZnMn-N-C as a positive oxygen reduction catalyst has a high energy density of 889 Wh / kg-1 Zn.

Description

A bimetallic active site doped carbon-based catalyst, a preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical catalysts, in particular to a bimetallic active site doped carbon-based catalyst and application thereof. BACKGROUND

[0002] With the in-depth research on reducing or replacing platinum-based catalysts with non-noble metals in fuel cells, carbon-based catalysts have become a popular exploration direction for preparing high-performance non-platinum ORR electrocatalysts due to their excellent electrical conductivity, stability and porous structure. Emerging transition metal iron-nitrogen doped carbon single-atom catalysts (Fe-N-C SACs) have unique structures and excellent catalytic activity, and have become the current main direction. However, the serious Fenton reaction will cause the stability of the catalyst to deteriorate and reduce the performance and safety of electrochemical conversion devices. On the contrary, Mn / Zn-N-C has intrinsic activity close to Fe-N-C in the ORR process, and the Fenton reaction is negligible. Therefore, preparing non-Fe-based oxygen reduction catalysts with a large number of accessible active sites is a feasible solution to replace Pt-based catalysts at present.

[0003] Currently, the preparation of Mn / Zn-N-C composite materials is to first form a microporous structure precursor with zinc salt and dimethyl imidazole, and then form a mesoporous structure in the microporous structure precursor, to form a Mn / Zn-N-C composite material coexisting microporous and mesoporous structures. The microporous structure can increase the adsorption amount of Zn and Mn, and the mesoporous structure can expose more active sites of the catalyst, and the two can synergistically act to improve the catalytic activity. However, the micropores are first formed and then the mesopores are formed on the basis of the micropores, which is at the expense of the microporous structure. The more mesopores formed by such a process route, the more the microporous structure will be sharply reduced, and the overall performance is not ideal. SUMMARY

[0004] The present application aims to provide a preparation method of a bimetallic active site doped carbon-based catalyst. In the method, the micropores are first formed and then the mesopores are formed, so as to obtain a bimetallic active site doped carbon-based catalyst coexisting more abundant mesopores and micropores, and effectively improve the catalytic activity of the catalyst.

[0005] Another object of the present application is to provide a bimetallic active site doped carbon-based catalyst prepared by the above method.

[0006] The object of the present application is achieved by the following technical solutions:

[0007] The application discloses a bimetallic active site doped carbon-based catalyst, in particular a ZnMn-N-C catalyst, which is characterized in that 1H-1,2,3-triazole, manganese nitrate and zinc chloride are used as reaction raw materials, Mn-MET-ZnCl2 powder is obtained through a solvothermal reaction and drying, and then the ZnMn-N-C catalyst is obtained through a first pyrolysis, sulfuric acid treatment and a second pyrolysis in sequence, and the catalyst has a mesopore distribution and a hierarchical pore structure of micropores further distributed in the mesopores.

[0008] Further, the manganese nitrate is prepared into a manganese nitrate aqueous solution with a mass concentration of 45-55%, and the amount ratio of 1H-1,2,3-triazole, the manganese nitrate aqueous solution and zinc chloride is 300-400 muL:200-300 muL:1-2 g.

[0009] Further, the temperature of the solvothermal reaction is 80-120 DEG C, and the reaction time is 12-48 h.

[0010] Further, the first pyrolysis is to heat the product obtained through the first pyrolysis to 400-500 DEG C at a heating rate of 3-5 DEG C / min, keep the temperature for 30-40 min, then heat to 800-1000 DEG C at the same heating rate, and keep the temperature for 1-2 h.

[0011] Further, the sulfuric acid treatment is to put the product obtained through the first pyrolysis into a sulfuric acid solution with a concentration of 0.5-1 mol / L, stir at 60-80 DEG C for 10-12 h, then clean and filter with ultrapure water and dry to obtain a first zinc / manganese single-atom carbon-based oxygen reduction catalyst.

[0012] Further, the second pyrolysis is to pyrolyze the product obtained through the first pyrolysis in an argon environment at 800-1000 DEG C, and the pyrolysis time is 1-2 h.

[0013] The application discloses a bimetallic active site doped carbon-based catalyst, in particular a ZnMn-N-C catalyst, which is characterized in that 1H-1,2,3-triazole, manganese nitrate and zinc chloride are used as reaction raw materials, Mn-MET-ZnCl2 powder is obtained through a solvothermal reaction and drying, and then the ZnMn-N-C catalyst is obtained through a first pyrolysis, sulfuric acid treatment and a second pyrolysis in sequence, and the catalyst has a mesopore distribution and a hierarchical pore structure of micropores further distributed in the mesopores.

[0014] Further, the manganese nitrate is prepared into a manganese nitrate aqueous solution with a mass concentration of 45-55%, and the amount ratio of 1H-1,2,3-triazole, the manganese nitrate aqueous solution and zinc chloride is 300-400 muL:200-300 muL:1-2 g.

[0015] Further, the temperature of the solvothermal reaction is 80-120 DEG C, and the reaction time is 12-48 h.

[0016] Further, the first pyrolysis is to increase the temperature to 400-500 DEG C at a rate of 3-5 DEG C / min, keep for 30-40 min, and then increase the temperature to 800-1000 DEG C at the same rate, and keep for 1-2 h.

[0017] In the present application, the mesoporous structure is first formed, and then micropores are further formed in the mesopores to form a nested doll type rich pore structure with micropores distributed in the mesopores. Compared with the prior art in which micropores are replaced by mesopores, the present application has more excellent specific surface area and richer pore structure, thereby achieving double improvement of the adsorption amount of metal ions and the amount of surface exposed active sites.

[0018] However, in the actual preparation process, a large number of mesopores are first prepared, and then micropores are formed in the mesopores. In the pore forming process, it is difficult to control the progress. The first formation of a large number of mesopores and the subsequent activation and modification of the mesoporous structure to generate micropores will cause serious problems of material structure collapse and dramatic decrease of catalytic performance.

[0019] Therefore, in the present application, Mn-MET-ZnCl2 powder is generated by solvothermal reaction of 1H-1,2,3-triazole, manganese nitrate and excess zinc chloride, and a segmented temperature rising pyrolysis is adopted. In the first temperature rising process, MET slowly thermally decomposes at a lower temperature to generate a large number of uniformly distributed mesopores. In this process, the excess zinc chloride gradually forms a molten structure. When the temperature rises to the second pyrolysis temperature, the molten zinc chloride is fully etched in the metal organic framework material to form a uniformly distributed microporous structure in the mesopores, so that the material obtains a high specific surface area hierarchical pore structure. In the pore forming process, the high specific surface area and the hierarchical pore structure with micropores distributed in the mesopores make the easily agglomerated metal Zn / Mn be anchored on the carbon skeleton with nitrogen defect position in the form of single atom, the content of Zn / Mn distributed in single atom is further improved, more active sites are exposed, the ORR activity is enhanced, in addition, the graphitization degree of the whole carbon material is increased, the improvement of the graphitization degree not only helps to improve the current density, but also improves the stability of the carbon material. The synergistic effect of the high specific surface area hierarchical pore structure and the single atom site is beneficial to improve the catalytic activity and battery performance of the catalyst.

[0020] Further, the sulfuric acid treatment is to put the product obtained by the first pyrolysis into a 0.5-1 mol / L sulfuric acid solution, stir at 60-80 DEG C for 10-12 h, then wash and filter with ultrapure water, and dry to obtain a first zinc / manganese single atom carbon-based oxygen reduction catalyst.

[0021] Further, the second pyrolysis is carried out at 800-1000 DEG C in an argon environment, and the pyrolysis temperature and time are 1-2 h.

[0022] The secondary step-by-step pyrolysis consolidates the carbon framework structure, so that the carbon structure with micropores in the mesopores is more stable.

[0023] A preparation method of a bimetallic active site doped carbon-based catalyst, characterized in that it comprises the following steps:

[0024] (1) 600-800 µL of 1H-1,2,3-triazole, 400-600 µL of a manganese nitrate aqueous solution with a mass concentration of 50%, and 2-4 g of ZnCl2 are added to 30-70 mL of N,N-dimethylformamide and ultrasonically mixed uniformly, and then transferred to a constant temperature condition of 80-120 ℃ for 12-24 h of solvothermal reaction;

[0025] (2) After the reaction is completed, centrifugation is performed, and then drying is performed in a constant temperature drying box at 60-80 ℃ to obtain Mn-MET-ZnCl2 powder;

[0026] (3) The Mn-MET-ZnCl2 powder dried in step (2) is uniformly ground in a garnet, and then subjected to primary pyrolysis, specifically, heated at a rate of 3~5 ℃ / min to 400~500 ℃, kept for 30~40 min, and then heated at the same rate to 800~1000 ℃, kept for 1~2 h;

[0027] (4) The product after primary pyrolysis is placed in a 0.5-1 mol / L sulfuric acid solution, and stirred at 60-80 ℃ for 10-12 h, and then dried after washing and suction filtration using ultrapure water to obtain a primary zinc / manganese monatomic carbon-based oxygen reduction catalyst;

[0028] (5) The primary zinc / manganese monatomic carbon-based oxygen reduction catalyst is transferred to a tube furnace filled with argon, and subjected to secondary pyrolysis at a temperature of 800~1000 ℃ for 1-2 h to obtain a ZnMn-N-C catalyst, which is a bimetallic site doped carbon-based catalyst.

[0029] The above-mentioned ZnMn-N-C catalyst is applied, specifically in the preparation of a zinc-air battery.

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

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

[0032] The ZnMn-N-C catalyst with the hierarchical pore structure prepared in the application has rich mesopores and micropores uniformly distributed in the mesopores. The rich mesopores in the battery electrode material play a role in transferring solutes and oxygen, and the micropores distributed therein effectively anchor more single-atom-distributed Zn / Mn, further enhancing the ORR activity, thereby improving the energy density and long-term stability of the battery.

[0033] The application has the following technical effects:

[0034] In the application, 1H-1, 2, 3-triazole and zinc chloride are used as pore-forming agents for mesopores and micropores respectively, the pore-forming sequence is adjusted and the pore-forming process is controlled through pyrolysis, a hierarchical pore structure is formed, the problem of pore structure collapse in forming the structure is solved, and a bimetallic site-doped carbon-based catalyst ZnMn-N-C with a high specific surface area of 1837.9 m² / g is obtained, which exhibits excellent ORR activity, E 1 / 2 = 0.867 V vs. RHE, and a primary zinc-air battery assembled by using the catalyst as a positive electrode oxygen reduction catalyst has a high energy density of 889 Wh / kg-1 Zn. BRIEF DESCRIPTION OF DRAWINGS

[0035] FIG. 1 is a SEM image of the ZnMn-N-C catalyst prepared in Example 3 of the application.

[0036] FIG. 2 is a TEM image of the ZnMn-N-C catalyst prepared in Example 3 of the application.

[0037] FIG. 3 is a HR-TEM image of the ZnMn-N-C catalyst prepared in Example 3 of the application.

[0038] FIG. 4 is a HAADF-STEM image of the ZnMn-N-C catalyst prepared in Example 3 of the application.

[0039] FIG. 5 is an XRD image of the ZnMn-N-C catalyst prepared in Example 3 of the application.

[0040] FIG. 6 is a N2 adsorption-desorption isotherm of the ZnMn-N-C catalyst prepared in Example 3 of the application (the inset is the pore size distribution).

[0041] FIG. 7 is a comparison diagram of oxygen reduction LSV of the ZnMn-N-C catalyst prepared in the application and a commercial Pt / C catalyst.

[0042] FIG. 8 is a comparison diagram of oxygen reduction LSV of the ZnMn-N-C catalyst prepared in the application and a Pt / C catalyst.

[0043] FIG. 9 is a comparison diagram of the energy density of a primary zinc-air battery assembled by using the ZnMn-N-C catalyst prepared in the application and a Pt / C catalyst.

[0044] Figure 10: Long time constant current density discharge plot of a primary zinc-air battery assembled with the bimetallic active site doped carbon-based catalyst prepared by the present application.

[0045] Figure 11: Comparison of charge / discharge cycling test of a rechargeable zinc-air battery assembled with the ZnMn-N-C catalyst prepared by the present application and a commercial Pt / C catalyst. DETAILED DESCRIPTION

[0046] The present application will be described in detail below by way of examples, which are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application.

[0047] Example 1

[0048] A preparation method of a bimetallic active site doped carbon-based catalyst, comprising the following steps:

[0049] (1) 600 μL of 1H-1,2,3-triazole, 600 μL of a manganese nitrate aqueous solution with a mass concentration of 50%, and 2 g of ZnCl2 were added to 30 mL of N,N-dimethylformamide and ultrasonically mixed uniformly, and then transferred to a constant temperature condition of 100°C for 18 h of solvothermal reaction;

[0050] (2) After the reaction, centrifugation was performed, and then placed in a constant temperature drying box at 70°C for drying to obtain Mn-MET-ZnCl2 powder;

[0051] (3) The Mn-MET-ZnCl2 powder dried in step (2) was uniformly ground in a garnet, and then subjected to a first pyrolysis, specifically, heated to 400°C at a rate of 4°C / min, kept for 40 min, and then heated to 1000°C at the same heating rate, kept for 1.5 h;

[0052] (4) The product after the first pyrolysis was placed in a 0.8 mol / L sulfuric acid solution, and stirred at 70°C for 12 h, and then washed and filtered with ultrapure water and dried to obtain a primary zinc / manganese monatomic carbon-based oxygen reduction catalyst;

[0053] (5) The primary zinc / manganese monatomic carbon-based oxygen reduction catalyst was transferred to a tube furnace filled with argon, and subjected to a second pyrolysis at a temperature of 1000°C for 1 h to obtain a ZnMn-N-C catalyst, which is a bimetallic active site doped carbon-based catalyst.

[0054] Example 2

[0055] A preparation method of a bimetallic active site doped carbon-based catalyst, comprising the following steps:

[0056] (1) 800 μL of 1H-1,2,3-triazole, 400 μL of a 50% by mass aqueous manganese nitrate solution, and 4 g of ZnCl2 were added to 70 mL of N,N-dimethylformamide and ultrasonically mixed until uniform, and then transferred to a constant temperature bath at 80°C and subjected to a solvothermal reaction for 12 h;

[0057] (2) After the reaction, centrifugation was performed, and then drying was performed in a constant temperature drying oven at 80°C to obtain Mn-MET-ZnCl2 powder;

[0058] (3) The Mn-MET-ZnCl2 powder dried in step (2) was ground in an agate mortar until uniform, and then subjected to a first pyrolysis by increasing the temperature to 400°C at a rate of 3°C / min, maintaining the temperature for 40 min, and then increasing the temperature to 1000°C at the same rate, maintaining the temperature for 1 h;

[0059] (4) The product after the first pyrolysis was placed in a 1 mol / L sulfuric acid solution and stirred at 60°C for 10 h, and then subjected to suction filtration using ultrapure water and dried to obtain a first zinc / manganese monatomic carbon-based oxygen reduction catalyst;

[0060] (5) The first zinc / manganese monatomic carbon-based oxygen reduction catalyst was transferred to a tube furnace filled with argon and subjected to a second pyrolysis at a temperature of 800°C for 2 h to obtain a ZnMn-N-C catalyst, which is a bimetallic site-doped carbon-based catalyst.

[0061] The bimetallic site-doped carbon-based catalyst ZnMn-N-C obtained in this example has a high specific surface area of 1829.8 m² / g, and the Zn / Mn-N x The content of active sites is 21.35%, and the catalyst exhibits excellent ORR activity, with E 1 / 2 = 0.864 V vs. RHE.

[0062] Example 3

[0063] A method for preparing a bimetallic active site-doped carbon-based catalyst, comprising the following steps:

[0064] (1) 740 μL of 1H-1,2,3-triazole, 585 μL of a 50% by mass aqueous manganese nitrate solution, and 3.4 g of ZnCl2 were added to 50 mL of N,N-dimethylformamide and ultrasonically mixed until uniform, and then transferred to a constant temperature bath at 120°C and subjected to a solvothermal reaction for 24 h;

[0065] (2) After the reaction, centrifugation was performed, and then drying was performed in a constant temperature drying oven at 60°C to obtain Mn-MET-ZnCl2 powder;

[0066] (3) The Mn-MET-ZnCl2 powder dried in step (2) is ground in a agate to be uniform, and then pyrolysis is carried out once, specifically, the temperature is raised to 450 ℃ at a rate of 5 ℃ / min, and kept for 35 min, and then the temperature is raised to 900 ℃ at the same rate, and kept for 2 h;

[0067] (4) The product after the first pyrolysis is placed in a 0.5 mol / L sulfuric acid solution, and stirred at 80 ℃ for 12 h, and then washed and filtered using ultrapure water, and dried to obtain a first zinc / manganese monatomic carbon-based oxygen reduction catalyst;

[0068] (5) The first zinc / manganese monatomic carbon-based oxygen reduction catalyst is transferred to a tube furnace filled with argon, and secondary pyrolysis is carried out at a temperature of 900 ℃, and the holding time is 1 h, to obtain a ZnMn-N-C catalyst, which is a bimetallic site doped carbon-based catalyst.

[0069] The bimetallic site doped carbon-based catalyst ZnMn-N-C prepared in Example 3 has a high specific surface area of 1830.1 m² / g, and the Zn / Mn-N x The content of active sites is 22.16%, which shows excellent ORR activity, E 1 / 2 = 0.870 V vs. RHE.

[0070] Figure 1 is an SEM image of the ZnMn-N-C catalyst prepared in Example 3, which can be seen to have a three-dimensional morphology with a rich porous structure, and has a rich mesoporous structure, and a large number of micropores are distributed inside the mesopores, which is due to the organic ligand of 1H-1,2,3-triazole forming a metal organic framework material, which is decomposed to form a mesoporous structure during the first pyrolysis, and the excess ZnCl2 in a molten state can provide pore-forming ability at a high temperature to form a microporous structure, thereby realizing a hierarchical pore structure of micropores distributed in mesopores. Figure 2 is a TEM image of the ZnMn-N-C catalyst prepared in this example, which can be seen to form a three-dimensional porous structure.

[0071] Figure 3 is a high-resolution transmission electron microscope (HR-TEM) image of the ZnMn-N-C catalyst prepared in Example 3, and the irregular lattice fringes indicate that the carbon matrix has an amorphous nature; the selected area electron diffraction pattern in the inset also proves that there are no crystals in the entire carbon matrix, which shows that the metal Zn / Mn is successfully embedded in the carbon matrix in the form of a monatomic.

[0072] Figure 4 is an aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of the ZnMn-N-C catalyst prepared in Example 3, and the single bright dots directly prove the dispersion of Zn / Mn atoms, proving that the synthesized ZnMn-N-C catalyst has abundant and uniformly dispersed single-atom Zn / Mn sites.

[0073] Figure 5 is an X-ray diffraction pattern of the ZnMn-N-C catalyst prepared in Example 3, indicating that it does not have a crystalline structure of metal.

[0074] To analyze the content of the transition metal Zn / Mn-N x active sites, X-ray photoelectron spectroscopy (XPS) was used for testing. As shown in Figure 6, the Zn / Mn-N x active sites have a content as high as 21.83%. The presence of high content of active sites indicates that the endogenous doping of excess ZnCl2 not only realizes pore formation inside the metal-organic framework material, but also successfully anchors the easily agglomerated metal Mn / Zn in the form of single atoms on the carbon skeleton with defects.

[0075] Figure 7 is a typical type IV nitrogen adsorption-desorption isotherm exhibited by the ZnMn-N-C catalyst prepared in Example 3, and the pore size distribution indicates that the ZnMn-N-C catalyst has a mesopore-dominated hierarchical pore structure, with a specific surface area as high as 1837.9 m 2 g -1 , and a large number of micropores exist inside the hierarchical porous structure, which can accelerate electron transfer and mass transfer.

[0076] As shown in the LSV curve in Figure 8, the catalyst has excellent electrochemical performance, and as can be seen from the figure, the ZnMn-N-C catalyst prepared in Example 3 exhibits more excellent ORR activity (E 1 / 2 = 0.867 V vs. RHE, J L = 5.9 mA cm -2 ) than Pt / C (E 1 / 2 = 0.86 V vs. RHE, J L = 5.81 mA cm -2 ).

[0077] Comparative Example 1

[0078] Compared with Example 3, in the one-step pyrolysis process, the same rate was directly increased to 900°C, and the temperature was kept for 2 h; the remaining steps were the same as those in Example 3.

[0079] Due to the direct heating to a high temperature of 900℃ in one pyrolysis process, the decomposition of MET gradually intensifies with the increase of temperature, leading to poor stability in the mesopore formation process. In the subsequent heat preservation process, the excess zinc chloride collapses a large number of mesopores when micropores are formed, resulting in that no rich mesopores are formed in the carbon material, the hierarchical pore structure of the uniformly distributed micropores in the interior is significantly reduced, and the BET specific surface area is detected to be 844.7 m 2 g -1 , the content of the active site of Zn / Mn-N x is 9.16%.

[0080] Example 4

[0081] Application of the bimetallic site doped carbon-based catalyst (ZnMn-N-C) in the preparation of a primary zinc-air battery and a rechargeable zinc-air battery:

[0082] 2 mg of the ZnMn-N-C catalyst prepared in Example 3 is uniformly dispersed in a mixed solution composed of 195 μL of ethanol and 5 μL of naphthol, and then uniformly coated on a 4 cm 2 carbon cloth as a positive electrode oxygen reduction catalyst, a Zn sheet with a thickness of 0.2 mm is selected as a negative electrode, and a 6 mol / L KOH solution is used as an electrolyte to assemble a primary zinc-air battery.

[0083] Control group: replace the ZnMn-N-C catalyst prepared in Example 3 with a commercially purchased Pt / C catalyst, and assemble a primary zinc-air battery according to the same method.

[0084] FIG. 9 is a comparison diagram of the energy density of the primary zinc-air battery assembled by the ZnMn-N-C catalyst prepared in Example 3 and the commercial Pt / C catalyst; as shown in the figure, when discharging at a fixed current density of 50 mA / cm 2 , the primary zinc-air battery assembled by the Mn-N@8Gra-L catalyst has a high energy density of 889 Wh / kg-1 Zn, which is much higher than the energy density (763 Wh / kg-1 Zn) of the primary zinc-air battery assembled by the Pt / C catalyst.

[0085] FIG. 10 is a long-time discharge of the primary zinc-air battery prepared in Example 4 at a fixed current density of 50 mA / cm 2 . After experiencing a constant current density discharge for 150 h, the discharge voltage of the primary zinc-air battery assembled by it only presents a decrease of 49 mV.

[0086] Example 5

[0087] Application of the bimetallic site doped carbon-based catalyst (ZnMn-N-C) in the preparation of a rechargeable zinc-air battery:

[0088] 2 mg ZnMn-N-C catalyst prepared in Example 3 and 2 mg RuO2 were weighed and uniformly dispersed in a mixed solution of 390 μL ethanol and 10 μL naphthol, and then uniformly coated on a 4 cm 2 A zinc-air battery was assembled by using the carbon cloth coated with the ZnMn-N-C catalyst prepared in Example 3 as the positive electrode oxygen reduction catalyst, a Zn sheet with a thickness of 0.2 mm as the negative electrode, and a mixed solution of KOH and Zn(Ac)2 as the electrolyte; the concentration of the KOH was 6 mol / L, and the concentration of the Zn(Ac)2 was 0.2 mol / L.

[0089] Control group: a commercial Pt / C catalyst was used instead of the ZnMn-N-C catalyst prepared in Example 3, and a zinc-air battery was prepared by the same method as described above for comparison.

[0090] As shown in FIG. 11, the zinc-air battery assembled by using the ZnMn-N-C catalyst and RuO2 in Example 5 had a discharge voltage of 1.1664 V and a charge voltage of 2.0271 V, and the difference between the charge voltage and the discharge voltage was 86.1 mV, while the zinc-air battery assembled by using Pt / C and RuO2 had a larger difference between the charge voltage and the discharge voltage (90 mV), indicating that the ZnMn-N-C catalyst had better long-term cycle stability when applied to the zinc-air battery.

Claims

1. A bimetallic active site-doped carbon-based catalyst ZnMn-N-C, characterized in that: The 1H-1,2,3-triazole, manganese nitrate and zinc chloride are used as reaction raw materials, and the Mn-MET-ZnCl2 powder is obtained through a solvothermal reaction and drying, and then the ZnMn-N-C catalyst is obtained through a first pyrolysis, sulfuric acid treatment and a second pyrolysis, and the catalyst has a mesoporous distribution and a hierarchical pore structure with micropores in the mesopores.

2. The bimetallic active site-doped carbon-based catalyst of claim 1, wherein: The manganese nitrate is prepared into a manganese nitrate aqueous solution with a mass concentration of 45-55%, and the amount ratio of the 1H-1,2,3-triazole, the manganese nitrate aqueous solution and the zinc chloride is 300-400 μL:200-300 μL:1-2 g.

3. The bimetallic active site-doped carbon-based catalyst of claim 2, wherein: The first pyrolysis is to heat to 400-500 ℃ at a rate of 3-5 ℃ / min, keep for 30-40 min, and then heat to 800-1000 ℃ at the same rate, and keep for 1-2 h.

4. A method of making a bimetallic active site doped carbon-based catalyst, characterized by: The 1H-1,2,3-triazole, manganese nitrate and zinc chloride are used as reaction raw materials, and the Mn-MET-ZnCl2 powder is obtained through a solvothermal reaction and drying, and then the ZnMn-N-C catalyst is obtained through a first pyrolysis, sulfuric acid treatment and a second pyrolysis.

5. The method of making a bimetallic active site doped carbon-based catalyst according to claim 4, wherein: The manganese nitrate is prepared into a manganese nitrate aqueous solution with a mass concentration of 45-55%, and the amount ratio of the 1H-1,2,3-triazole, the manganese nitrate aqueous solution and the zinc chloride is 300-400 μL:200-300 μL:1-2 g.

6. The method of making a bimetallic active site doped carbon-based catalyst according to claim 5, wherein: The temperature of the solvothermal reaction is 80-120 ℃, and the reaction time is 12-48 h.

7. The method of making a bimetallic active site doped carbon-based catalyst according to claim 6, wherein: The first pyrolysis is to heat to 400-500 ℃ at a rate of 3-5 ℃ / min, keep for 30-40 min, and then heat to 800-1000 ℃ at the same rate, and keep for 1-2 h.

8. The method of making a bimetallic active site doped carbon-based catalyst according to claim 7, wherein: The sulfuric acid treatment is to put the product obtained through the first pyrolysis into a 0.5-1 mol / L sulfuric acid solution, stir at 60-80 ℃ for 10-12 h, then clean and filter with ultrapure water, and dry to obtain the first zinc / manganese monatomic carbon-based oxygen reduction catalyst.

9. The method of making a bimetallic active site doped carbon-based catalyst according to claim 8, wherein: The second pyrolysis is to pyrolyze under an argon gas environment at 800-1000 ℃, and the pyrolysis time is 1-2 h.

Images