Method for preparing carbon black support loaded hierarchical pore non-noble metal fuel cell catalyst

Abstract

This invention discloses a method for preparing a carbon black-supported hierarchical porous non-precious metal fuel cell catalyst, comprising the following steps: adding a metal salt to a solvent to obtain solution A; adding 2-methylimidazolium and imidazolium derivatives to a solvent to obtain solution B; mixing solutions A and B and then centrifuging to obtain a MOF precursor; placing the MOF precursor in a tube furnace to obtain carbonized NC powder; adding conductive carbon black to a solvent and ultrasonically dispersing to obtain solution C; adding the NC powder to solution C, dispersing it evenly, adding an active metal solution to obtain an active metal-supported solution D, and drying to obtain a powder with active metal sites supported on carbon black; and programmatically heating the obtained powder to obtain an M-NC@carbon black catalyst. The catalyst prepared by this method, using carbon black-supported MOF material as a support, can improve conductivity and solve problems such as poor oxygen intermediate transport capacity and inaccessible active sites in catalytic materials.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for preparing a multi-level porous non-precious metal fuel cell catalyst supported on a carbon black carrier. Background Technology

[0002] Fuel cells, as efficient and clean energy conversion devices, have attracted much attention in recent years. Among them, hydrogen fuel cells, as a potential alternative energy technology, have enormous development potential. Hydrogen fuel cells generate electricity by reacting hydrogen with oxygen, producing only water as a byproduct, thus being considered a zero-emission energy solution. A hydrogen fuel cell mainly consists of an anode end plate, anode bipolar plate, anode gas diffusion layer, anode catalyst layer, proton exchange membrane, cathode catalyst layer, cathode gas diffusion layer, cathode bipolar plate, and cathode end plate. The fuel cell catalyst is a crucial component. Traditionally, hydrogen fuel cell catalysts have primarily used precious metals such as platinum and palladium; however, the high cost, scarcity of resources, and insufficient resistance to toxicity of these materials have limited the commercial application of hydrogen fuel cells.

[0003] To overcome the shortcomings of traditional noble metal catalysts, researchers have been exploring novel non-noble metal catalysts in recent years, such as transition metal oxides, transition metals, and nitrogen-co-doped carbon materials. These novel catalysts possess abundant active sites, excellent electrochemical performance, and lower cost, offering new possibilities for the commercial application of hydrogen fuel cells. However, non-noble metal catalysts still face some challenges in practical applications. For example, their activity is often lower than that of noble metal catalysts, resulting in unsatisfactory electrocatalytic performance in fuel cells. Furthermore, the stability and durability of non-noble metal catalysts also face significant challenges, with performance degradation and deactivation easily occurring during long-term operation, limiting their large-scale application.

[0004] MNC (Mesopore-Negative Coal) catalysts (M for transition metal, N for nitrogen, and C for carbon) have been proven to have excellent cathodic oxygen reduction performance and are considered the most promising low-cost electrocatalysts to replace noble metal catalysts. Single-atom catalysts can achieve the highest atom utilization rate, and their atomic configuration allows for the rational optimization of the electronic and geometric structures, which can greatly improve the activity and stability of the catalyst. Single-atom catalysts generally consist of active metals attached as individual atoms to a conductive support, most commonly carbon supports. Therefore, the conductivity and stability of the carbon support often have a significant impact on the activity and stability of the catalyst. Furthermore, micropores constitute the majority of MOF-based catalysts, which is beneficial for increasing the specific surface area and adsorption of active sites, but hinders the conduction of oxygen intermediates, thus inhibiting the oxygen reduction activity of the catalyst. Therefore, adjusting the ratio of mesopores to micropores in MOF materials to increase the exposure of active sites and the mass transfer rate of oxygen intermediates is of great significance for improving the oxygen reduction activity of catalysts. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a multi-level porous non-precious metal fuel cell catalyst supported on a carbon black support; the catalyst prepared by this method with MOF material as support can improve conductivity and solve the problems of poor oxygen intermediate transport capacity and inaccessible active sites in catalytic materials.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a hierarchical porous non-precious metal fuel cell catalyst supported on a carbon black support includes the following steps: 1) Add the metal salt to the solvent, sonicate and stir to mix evenly to obtain metal ligand solution A; 2) Add 2-methylimidazole and imidazole derivatives to a solvent, sonicate and stir to mix evenly to obtain organic ligand solution B; 3) The metal ligand solution A and the organic ligand solution B are mixed and reacted for 1-20 h. After centrifugation, washing and drying, a MOF precursor with a microporous / mesoporous structure is obtained. 4) After grinding the MOF precursor into powder, it is placed in a tube furnace and heated to a certain temperature under a protective gas and held for a certain time to obtain carbonized NC powder. 5) Add conductive carbon black to the solvent and disperse it completely to obtain solution C; 6) Add the NC powder obtained in step 4) to solution C and disperse it evenly. Then add the active metal solution and stir vigorously at a certain temperature for 1-24 hours to obtain the active metal loaded solution D. After centrifugation, acid washing, washing and drying, obtain the powder loaded on carbon black with active metal sites. 7) The powder with active metal sites obtained in step 6) is ground and placed in a tube furnace. Under a protective gas, the temperature is programmed to rise to 700-1200℃ and held for 1-5 hours to obtain a carbon black-supported hierarchical porous non-precious metal fuel cell catalyst, named M-NC@carbon black.

[0007] Preferably, in step 1), the metal salt is one of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc chloride (ZnCl2), and zinc carbonate (ZnCO3); the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol.

[0008] Preferably, in step 1), the concentration of the metal salt is 50-200 mM; in step 2), the concentration of the organic ligand is 400-1600 mM; and the mass ratio of 2-methylimidazole to imidazole derivatives is 0.1:0.9-0.9:0.1.

[0009] Preferably, in step 2), the imidazole derivative includes aminoimidazolium compounds and aminobenzimidazole compounds; the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol; more preferably, the aminoimidazolium compound is one of 2-aminoimidazolium, 4-aminoimidazolium, and 5-amino-4-imidazolium carboxamide; even more preferably, the aminobenzimidazole compound is one of 2-aminobenzimidazole, 2-methylbenzimidazole, and benzimidazole-5-carboxylic acid.

[0010] Preferably, in step 3), the reaction method between solution A and solution B includes stirring, microchannel, microwave, ultrasound, etc.

[0011] Preferably, in step 4), the temperature of the programmed heating is 950-1150℃, the heating rate is 2-5℃ / min, and the holding time is 2-5h.

[0012] Preferably, in step 5), the conductive carbon black is one of VULCAN XC-72, KETJENBLACK EC-300J or EC-600JD; the carbon black is dispersed by ultrasonication, high shear, vibration, stirring, etc.

[0013] Preferably, in step 6), the active metal solution includes one or two of iron, copper, manganese, cobalt, nickel, and chromium; the dispersion method is ultrasonication or stirring; and the loading temperature is 20-60℃.

[0014] Preferably, in step 6), the mass of conductive carbon black in solution C is 2-6 times that of NC powder.

[0015] Preferably, in step 6), the mass of the active metal in the active metal solution is 1 / 4 to 1 / 20 of the mass of the NC powder.

[0016] Preferably, in step 6), the pickling process uses sulfuric acid or nitric acid, the pickling time is 2-6 hours, and the temperature is 30-80℃.

[0017] Preferably, in step 6), the centrifugation speed is 8000-12000 rpm and the time is 5-20 min.

[0018] Preferably, in step 6), the washing process uses anhydrous methanol, anhydrous ethanol, deionized water, or DMF, and the washing is performed at least three times.

[0019] Preferably, in step 6), the drying temperature is 60-100℃ and the time is 6-12h.

[0020] Preferably, in step 7), the protective gas is one of nitrogen, argon, and helium.

[0021] Preferably, in step 7), the temperature of the programmed heating is 950-1150℃.

[0022] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0023] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention utilizes conductive carbon black to support a non-precious metal single-atom catalyst on a MOF (Metal-Oxide-Foil) carrier. The active metal atoms are anchored on the NC (Non-Metal-Oxide) structure of the MOF and integrally loaded onto the conductive carbon black. Leveraging the excellent conductivity of carbon black, the electronic conductivity of the catalytic material is improved, thereby significantly enhancing the oxygen reduction activity and stability of the catalyst. Furthermore, the carbon black material used has a simple production process and is inexpensive, providing a foundation for the large-scale application of fuel cells.

[0026] 2. This invention provides a method for synthesizing MOF materials with a more suitable micropore / mesopore ratio by changing the concentration of the metal salt solution, the concentration and ratio of the organic ligand solution, the type and amount of the active metal, the reaction temperature, and the reaction time. This method can adjust the micropore to mesopore ratio of the MOF material, ensuring a sufficiently large specific surface area for adsorbing active sites while introducing mesopores to enhance the mass transfer rate of oxygen intermediates, thereby ensuring the transport efficiency of oxygen intermediates and enhancing the electrocatalytic activity of the catalyst. Attached Figure Description

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Figure 1 The experimental flowchart of the preparation method of the present invention is shown; Figure 2 The image shows a SEM image of the sample prepared in Example 1 of the present invention; Figure 3 The image shows a SEM image of the sample prepared in Example 2 of the present invention; Figure 4 The SEM image of the sample prepared in Comparative Example 1 of the present invention is shown. Figure 5 The SEM image of the sample prepared in Comparative Example 2 of this invention is shown. Figure 6 The oxygen reduction performance curves of the samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention in 0.1M KOH solution are shown. Figure 7 The oxygen reduction performance curves of the samples prepared in Example 2 and Comparative Example 3 of the present invention in 0.1M KOH solution are shown. Figure 8 The power density curves of the samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention are shown in the figure. Figure 9 The power density curves of the samples prepared in Example 2 and Comparative Example 3 of the present invention are shown in hydrogen-oxygen fuel cells. Detailed Implementation

[0028] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0029] As one aspect of the present invention, a method for preparing a hierarchical porous non-precious metal fuel cell catalyst supported on a carbon black support includes the following steps: 1) Add the metal salt to the solvent, sonicate and stir to mix evenly to obtain metal ligand solution A; 2) Add 2-methylimidazole and imidazole derivatives to a solvent, sonicate and stir to mix evenly to obtain organic ligand solution B; 3) The metal ligand solution A and the organic ligand solution B are mixed and reacted for 1-20 h. After centrifugation, washing and drying, a MOF precursor with a microporous / mesoporous structure is obtained. 4) After grinding the MOF precursor into powder, it is placed in a tube furnace and heated to a certain temperature under a protective gas and held for a certain time to obtain carbonized NC powder. 5) Add conductive carbon black to the solvent and sonicate for 8-12 minutes to completely disperse it to obtain solution C; 6) Add the NC powder obtained in step 4) to solution C and disperse it evenly. Then add the active metal solution and stir vigorously at a certain temperature for 1-24 hours to obtain the active metal loaded solution D. After centrifugation, acid washing, washing and drying, obtain the powder loaded on carbon black with active metal sites. 7) The powder with active metal sites obtained in step 6) is ground and placed in a tube furnace. Under a protective gas, the temperature is programmed to rise to 700-1200℃ and held for 1-5 hours to obtain a carbon black-supported hierarchical porous non-precious metal fuel cell catalyst, named M-NC@carbon black.

[0030] In other words, this invention involves first preparing the MOF material, and then mixing it with a carbon black support to achieve the purpose of loading the MOF material onto the carbon black. Furthermore, the catalytic sites of the catalyst in this invention are loaded onto the MOF material through stirring, and can be metals such as iron, copper, manganese, cobalt, nickel, and chromium.

[0031] According to certain embodiments of the present invention, in step 1), the metal salt is one of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc chloride (ZnCl2), and zinc carbonate (ZnCO3); the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol.

[0032] According to certain embodiments of the present invention, in step 1), the concentration of the metal salt solution is 50-200 mM, the concentration of the organic ligand solution is 400-1600 mM, and the mass ratio of 2-methylimidazole to imidazole derivative is 0.1:0.9-0.9:0.1; for example, but not limited to 0.1:0.9, 0.3:0.7, 0.5:0.5, 0.7:0.3 or 0.9:0.1.

[0033] According to certain embodiments of the present invention, in step 2), the imidazole derivative includes an aminoimidazolium compound and an aminobenzimidazole compound; the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol; more preferably, the aminoimidazolium compound is one of 2-aminoimidazolium, 4-aminoimidazolium, and 5-amino-4-imidazolium carboxamide; even more preferably, the aminobenzimidazole compound is one of 2-aminobenzimidazole, 2-methylbenzimidazole, and benzimidazole-5-carboxylic acid.

[0034] According to certain embodiments of the present invention, in step 3), the reaction method between solution A and solution B includes stirring, microchannel, microwave, ultrasound, etc.

[0035] According to some embodiments of the present invention, in step 4), the temperature of the programmed heating is 700-1200℃, the heating rate is 2-10℃ / min, and the holding time is 1-10h.

[0036] According to certain embodiments of the present invention, in step 5), the conductive carbon black is one of VULCAN XC-72, KETJENBLACK EC-300J or EC-600JD; the dispersion method of the carbon black includes ultrasonication, high shear, vibration, stirring, etc.

[0037] According to certain embodiments of the present invention, in step 6), the active metal solution includes one or two of iron, copper, manganese, cobalt, nickel, and chromium; the dispersion method includes ultrasonication, high shear, stirring, etc.; and the loading temperature is 20-60℃.

[0038] According to certain embodiments of the present invention, in step 6), the mass of conductive carbon black in solution C is 2-6 times that of NC powder.

[0039] According to certain embodiments of the present invention, in step 6), the mass of the active metal in the active metal solution is 1 / 4 to 1 / 20 of the NC powder.

[0040] According to some embodiments of the present invention, in step 6), the pickling process uses sulfuric acid or nitric acid, the pickling time is 2-6 hours, and the temperature is 30-80°C.

[0041] According to certain embodiments of the present invention, in step 6), the centrifugation speed is 8000-12000 rpm and the time is 5-20 min.

[0042] According to certain embodiments of the present invention, in step 6), the washing process uses anhydrous methanol, anhydrous ethanol, deionized water or DMF, and the washing is performed at least 3 times.

[0043] According to certain embodiments of the present invention, in step 6), the drying temperature is 60-100°C and the time is 6-12 hours.

[0044] According to certain embodiments of the present invention, in step 7), the protective gas is one of nitrogen, argon, and helium.

[0045] According to some embodiments of the present invention, in step 7), the temperature of the programmed temperature rise is 950-1150°C. Example 1

[0046] A method for preparing a hierarchical porous non-precious metal fuel cell catalyst supported on a carbon black support includes the following steps: 1) Dissolve 1.487 g of Zn(NO3)2·6H2O in 100 mL of anhydrous methanol to prepare solution A with a concentration of 50 mM; 2) Dissolve 2.956 g of 2-methylimidazole and 0.328 g of 2-aminobenzimidazole in 100 mL of anhydrous methanol to prepare solution B with a concentration of 400 mM; 3) After mixing solutions A and B, the mixture was vigorously stirred at 1000 rpm for 12 h at room temperature, followed by centrifugation at 12000 rpm for 20 min. The resulting centrifuged slurry was washed three times with methanol and then dried in a vacuum drying oven at 70℃ for 12 h to obtain the ZIF-8 precursor. 4) After grinding the ZIF-8 precursor evenly, place it in a tube furnace, heat it to 1000℃ at a rate of 5℃ / min under nitrogen protection and hold it for 2h. After natural cooling, NC powder with microporous / mesoporous structure is obtained. 5) Add 400 mg of XC-72 carbon black to methanol solvent and sonicate for 10 min to disperse it completely, to obtain a carbon black solution; 6) Add 100 mg of the obtained NC powder to the carbon black solution and sonicate for 10 min. Take 500 μL of Fe(NO3)3·9H2O solution (concentration 20 mg·mL) −1 The catalyst was added to the above solution and sonicated for 10 min, then stirred at 1000 rpm for 4 h. After centrifugation, it was acid-washed with 0.5 M sulfuric acid solution at 50 °C for 5 h, and then dried in a vacuum drying oven at 70 °C for 12 h to obtain carbon black powder loaded with NC catalyst. 7) After grinding the powder evenly, place it in a tube furnace, heat it to 1000℃ at a rate of 5℃ / min under nitrogen protection and hold for 2h. After natural cooling, Fe-NC@carbon black catalyst is obtained.

[0047] To evaluate the oxygen reduction performance of the above catalyst, a rotating disk electrode test was performed on the catalyst. The specific steps are as follows: 1) The 2 mg Fe-NC@carbon black catalyst obtained in this example was dispersed in 300 μL isopropanol, 200 μL deionized water and 10 μL Nafion solution, and ultrasonicated for 60 minutes to obtain catalyst ink. 2) Place 10 μL of catalyst ink onto the glassy carbon electrode, let it air dry naturally, and then install it on the rotating rod; 3) Add 0.1M KOH to a five-necked flask and purge oxygen for at least 30 minutes to saturate the electrolyte with oxygen. 4) Under continuous oxygen supply, a linear voltammetric scan was performed using a three-electrode system, with a scan range of 1.0~0.2V. vs RHE), with a scan rate of 5 mV / s; 5) At a rotational speed of 1600 rpm, its half-wave potential is 887 mV; in a hydrogen-oxygen fuel cell, the peak power density can reach 1.15 W / cm². 2 .

[0048] Figure 2 The image shows a SEM image of the Fe-NC@carbon black catalyst sample prepared in Example 1.

[0049] Figure 6 The graph shows the oxygen reduction performance of the Fe-NC@carbon black catalyst in 0.1M KOH solution in Example 1.

[0050] Figure 8 The peak power density curve of the Fe-NC@carbon black catalyst in this Example 1 is shown. Example 2

[0051] A method for preparing a hierarchical porous non-precious metal fuel cell catalyst supported on a carbon black support includes the following steps: 1) Dissolve 4.464 g of Zn(NO3)2·6H2O in 100 mL of DMF to prepare solution A with a concentration of 150 mM; 2) Dissolve 6.896 g of 2-methylimidazole and 2.956 g of 4-aminoimidazole in 100 mL of DMF to prepare solution B with a concentration of 1200 mM; 3) After mixing solutions A and B, the mixture was vigorously stirred at 1000 rpm for 12 h at room temperature, followed by centrifugation at 10000 rpm for 20 min. The resulting centrifuged slurry was washed three times with DMF and then dried in a vacuum drying oven at 80 °C for 12 h to obtain the ZIF-8 precursor. 4) After grinding the ZIF-8 precursor evenly, place it in a tube furnace, heat it to 1100℃ at a rate of 4℃ / min under nitrogen protection and hold it for 2h. After natural cooling, NC powder with microporous / mesoporous structure is obtained. 5) Add 1000 mg of Ketjen Black EC-300J to the DMF solvent and sonicate for 10 min to disperse it completely; 6) Add 500 mg of the NC powder obtained above to the carbon black solution and sonicate for 10 min. Take 3 mL of Mn(NO3)2·6H2O solution (concentration 20 mg·mL) −1 Add the above solution and sonicate for 10 min, then stir at 1000 rpm for 4 h at 50 °C; after centrifugation, acid wash with 0.5 M sulfuric acid solution at 60 °C for 5 h, then place in a vacuum drying oven and dry at 80 °C for 12 h to obtain carbon black powder loaded with NC catalyst. 7) After grinding the powder evenly, put it into a tube furnace, heat it to 1100℃ at a rate of 4℃ / min under nitrogen protection and hold it for 2h. After natural cooling, the Mn-NC@carbon black catalyst is obtained. 8) Its oxygen reduction performance was tested in 0.1M KOH solution, and its half-wave potential was 870mV. In a hydrogen-oxygen fuel cell, the peak power density can reach 1.03 W / cm³. 2 .

[0052] Figure 3 The image shows a SEM image of the Mn-NC@carbon black catalyst sample prepared in Example 2.

[0053] Figure 7 The graph shows the oxygen reduction performance of the prepared sample Mn-NC@carbon black catalyst in 0.1M KOH solution in Example 2.

[0054] Figure 9 The peak power density curve of the prepared sample Mn-NC@carbon black catalyst in this Example 2 is shown. Comparative Example 1

[0055] Example 1 was repeated, except that conductive carbon black was not added. The NC powder obtained after calcining ZIF-8 was directly mixed with the active metal solution and sonicated for 10 min. Then it was stirred at 1000 rpm for 4 h. After centrifugation, acid washing, and drying, it was calcined. Nitrogen was used as the protective gas for calcination, the heating rate was 5 °C / min, and it was held at 1000 °C for 2 h to obtain the Fe-NC catalyst.

[0056] Its oxygen reduction performance was tested in 0.1M KOH solution, with a half-wave potential of 830 mV; in a hydrogen-oxygen fuel cell, the peak power density was 0.74 W / cm³. 2 .

[0057] Therefore, it is evident that without the addition of conductive carbon black, the oxygen reduction performance of the catalyst will decrease significantly.

[0058] Figure 4 The SEM image of the Fe-NC catalyst prepared in Comparative Example 1 is shown.

[0059] Figure 6 The graph shows the oxygen reduction performance of the Fe-NC catalyst prepared in Comparative Example 1 in 0.1M KOH solution.

[0060] Figure 8 The peak power density curve of the Fe-NC catalyst prepared in Comparative Example 1 in a hydrogen-oxygen fuel cell is shown. Comparative Example 2

[0061] Example 1 was repeated, except that the organic ligand solution used in the reaction process contained only 2-methylimidazole and did not contain imidazole derivatives. Specifically, Zn(NO3)2·6H2O solution was directly reacted with 2-methylimidazole solution under stirring, and the subsequent steps were the same as in Example 1, resulting in a ZIF-8 support without mesoporous structure. After calcination, a Fe-NC@carbon black catalyst with only micropores was obtained.

[0062] Its oxygen reduction performance was tested in 0.1M KOH solution, with a half-wave potential of 860mV; in a hydrogen-oxygen fuel cell, the peak power density was 0.9 W / cm³. 2 .

[0063] Therefore, it can be seen that without the addition of imidazole derivatives to the organic ligand solution, the oxygen reduction performance of the microporous / mesoporous hierarchical porous catalyst will decrease significantly.

[0064] Figure 5 The SEM image of the Fe-NC@carbon black catalyst prepared in Comparative Example 2 is shown.

[0065] Figure 6 The graph shows the oxygen reduction performance of the Fe-NC@carbon black catalyst prepared in Comparative Example 2 in 0.1M KOH solution.

[0066] Figure 8 The peak power density curve of the Fe-NC@carbon black catalyst prepared in Comparative Example 2 is shown. Comparative Example 3

[0067] Example 2 was repeated, except that conductive carbon black was not added. The NC powder obtained after calcining ZIF-8 was directly mixed with the active metal solution and sonicated for 10 min. Then, it was stirred at 1000 rpm for 4 h at 50 °C. After centrifugation, acid washing, and drying, it was calcined with nitrogen as the protective gas and the heating rate was 4 °C / min. It was held at 1100 °C for 2 h to obtain the Mn-NC catalyst.

[0068] Its oxygen reduction performance was tested in 0.1M KOH solution, with a half-wave potential of 840mV; in a hydrogen-oxygen fuel cell, the peak power density was 0.76 W / cm³. 2 .

[0069] Therefore, it is evident that without the addition of conductive carbon black, the oxygen reduction performance of the catalyst will decrease significantly.

[0070] Figure 7 The graph shows the oxygen reduction performance of the Mn-NC catalyst prepared in Comparative Example 3 in 0.1M KOH solution.

[0071] Figure 9The peak power density curve of the Mn-NC catalyst prepared in Comparative Example 3 in a hydrogen-oxygen fuel cell is shown.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a carbon black support loaded hierarchical pore non-precious metal fuel cell catalyst, characterized in that, Includes the following steps: 1) Add the metal salt to the solvent, sonicate and stir to mix evenly to obtain metal ligand solution A; 2) Add 2-methylimidazole and imidazole derivatives to a solvent, sonicate and stir to mix evenly to obtain organic ligand solution B; 3) The metal ligand solution A and the organic ligand solution B are mixed and reacted for 1-20 h. After centrifugation, washing and drying, a MOF precursor with a microporous / mesoporous structure is obtained. 4) After grinding the MOF precursor into powder, it is placed in a tube furnace and heated to a certain temperature under a protective gas and held for a certain time to obtain carbonized NC powder. 5) Add conductive carbon black to the solvent and disperse it completely to obtain solution C; 6) Add the NC powder obtained in step 4) to solution C and disperse it evenly. Then add the active metal solution and stir vigorously at a certain temperature for 1-24 hours to obtain the active metal loaded solution D. After centrifugation, acid washing, washing and drying, obtain the powder loaded on carbon black with active metal sites. 7) The powder with active metal sites obtained in step 6) is ground and placed in a tube furnace. Under a protective gas, the temperature is programmed to rise to 700-1200℃ and held for 1-5 hours to obtain a carbon black-supported hierarchical porous non-precious metal fuel cell catalyst, named M-NC@carbon black.

2. The method of claim 1, wherein: In step 1), the metal salt is one of zinc nitrate hexahydrate, zinc chloride, and zinc carbonate; the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol.

3. The method of claim 1, wherein: In step 1), the concentration of the metal salt is 50-200 mM; in step 2), the concentration of the organic ligand is 400-1600 mM, and the mass ratio of 2-methylimidazole to imidazole derivatives is 0.1:0.9-0.9:0.

1.

4. The method of claim 1, wherein: In step 2), the imidazole derivatives include aminoimidazolium compounds and aminobenzimidazole compounds; the solvent is one or more of anhydrous methanol, anhydrous ethanol, DMF, and isopropanol.

5. The method of claim 4, wherein: The aminoimidazolium compound is one of 2-aminoimidazolium, 4-aminoimidazolium, and 5-amino-4-imidazolium carboxamide.

6. The method of claim 4, wherein: The aminobenzimidazole compound is one of 2-aminobenzimidazole, 2-methylbenzimidazole, and benzimidazole-5-carboxylic acid.

7. The method of claim 1, wherein: In step 3), the reaction methods between solution A and solution B include stirring, microchannels, microwaves, or ultrasound.

8. The method of claim 1, wherein: In step 4), the temperature of the programmed heating is 700-1200℃, the heating rate is 2-10℃ / min, and the holding time is 1-10h.

9. The method of claim 1, wherein: In step 5), the conductive carbon black is one of VULCANX C-72, KETJENBLACK EC-300J or EC-600JD; the carbon black is dispersed by ultrasonication, high shear, vibration or stirring.

10. The method of claim 1, wherein: In step 6), the active metal solution includes one or two of iron, copper, manganese, cobalt, nickel, and chromium; the dispersion method includes ultrasonication, high shear, or stirring; and the loading temperature is 20-60℃.

11. The method of claim 1, wherein: In step 6), the mass of conductive carbon black in solution C is 2-6 times that of NC powder.

12. The method of claim 1, wherein: In step 6), the mass of the active metal in the active metal solution is 1 / 4 to 1 / 20 of the mass of the NC powder; In step 6), the pickling process uses sulfuric acid or nitric acid, and the pickling time is 2-6 hours, with a temperature of 30-80℃. In step 6), the centrifugation speed is 8000-12000 rpm and the time is 5-20 min; In step 6), the washing process uses anhydrous methanol, anhydrous ethanol, deionized water, or DMF, and the washing process is at least 3 times. In step 6), the drying temperature is 60-100℃ and the time is 6-12h; In step 7), the protective gas is one of nitrogen, argon, and helium; In step 7), the temperature of the programmed heating is 950-1150℃.

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