Nitrogen-doped ruthenium-cobalt-carbon material as cathode electrocatalyst for fuel cell and preparation method and application thereof

Abstract

The present application relates to the technical field of electrocatalyst of fuel cell, in particular to a fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material, a preparation method and application thereof, the MOF material of ZIF-67 is prepared, then the ZIF-67 material, ruthenium salt and carbon source are mixed and form a gel, then the ruthenium salt is reduced to disordered ruthenium nanoparticles at low temperature, and then high-temperature carbonization is experienced under inert atmosphere, to obtain the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material.The carbon material of the present application is doped with nitrogen atoms and is compounded with ruthenium and cobalt, the nitrogen atoms provide more electronic active sites, the electronic transmission speed of the porous carbon is improved, the porous carbon provides a crosslinked pore structure with large specific surface area, so that the nano ruthenium cobalt is stably attached to the porous carbon;The valence bond formed between cobalt and carbon can improve the interaction between cobalt and carbon, further improve the activity and stability of the catalyst, and then improve the catalytic performance of the Ru / C material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalysts of fuel cells, in particular to a nitrogen-doped ruthenium-cobalt-carbon material as a cathode electrocatalyst of fuel cells and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of science and technology and economic construction in the world, the energy crisis and environmental pollution problems have been highly valued by the people and governments of the world, so the research and development of clean and pollution-free new energy has become one of the international hotspots. Fuel cells have the advantages of high energy conversion efficiency and small environmental pollution, and have been highly valued in today's increasingly concerned social environment. Fuel cells are energy systems that convert chemical energy provided by fuel gas (hydrogen, methanol or other organic substances) and oxidant (oxygen or air) into electrical energy through electrochemical reactions. According to the operating conditions, fuel cells are divided into solid oxide electrolyte fuel cells, molten carbonate electrolyte fuel cells, phosphate electrolyte fuel cells and polymer electrolyte membrane fuel cells.

[0003] Polymer electrolyte membrane fuel cells include proton exchange membrane fuel cells (PEMFC) using hydrogen as fuel, and direct methanol fuel cells (DMFC) using liquid methanol as fuel. Direct methanol fuel cells are a kind of fuel cells using perfluorosulfonic acid membrane as electrolyte. Since direct methanol fuel cells have the characteristics of room temperature rapid start-up, high specific power and high specific energy, they have broad application prospects in the fields of fixed power stations, electric vehicles, military special power sources and portable power sources.

[0004] In a direct methanol fuel cell, the oxidation reaction occurs at the anode, and the protons and electrons generated by the anode oxidation reaction are transmitted to the cathode, and the protons and oxygen are combined to generate water at the cathode, and the electromotive force generated by the reduction of oxygen becomes the energy source of the fuel cell. The reactions occurring at the anode and the cathode are as follows: Anode: CH3OH + H2O → CO2 + 6H + + 6e - Ea=0.05V

[0005] Cathode: 3 / 2O2 + 6H + + 6e - → 3H2O Ec=1.23V

[0006] Overall reaction: CH3OH + 3 / 2O2 → CO2 + 2H2O E 电池 =1.18V

[0007] In order to improve the quality of fuel cells, Pt and Pt-based materials are currently known as widely used catalytic materials, but the scarcity and high cost of Pt are the main obstacles to the large-scale promotion of fuel cells, and Pt electrodes are easily poisoned by CO in fuel gas, which limits its further development; therefore, it is particularly important to find a replaceable catalytic material.

[0008] In recent years, Ru-based electrocatalysts have attracted widespread attention as a cheap alternative to Pt, but the exchange current density of Ru-based catalysts is much lower than that of Pt / C, so it is necessary to design reasonably to improve the catalytic performance of Ru / C materials as fuel cell cathode electrocatalysts. SUMMARY

[0009] In view of the deficiencies of the prior art, the purpose of the present application is to provide a fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt composite carbon material and its preparation method and application. The carbon material of the present application adopts nitrogen atom doping and composite with ruthenium and cobalt. The nitrogen atom provides more electronic active sites, improves the electronic transmission speed of the porous carbon, and the porous carbon provides a large specific surface area of cross-linked pore structure, so that the nano ruthenium and cobalt are stably attached to the porous carbon. The valence bond formed between cobalt and carbon can improve the interaction between cobalt and carbon, further improve the activity and stability of the catalyst, and then improve the catalytic performance of Ru / C material.

[0010] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0011] The preparation method of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt carbon material comprises the following steps:

[0012] (1) ZIF-67 material is prepared by taking cobalt salt and 2-methyl imidazole as raw materials. ZIF-67 is used to provide nitrogen, cobalt and carbon skeleton to realize nitrogen doping, cobalt composite and cobalt adhesion of carbon material. The preparation of ZIF-67 material by taking cobalt salt and 2-methyl imidazole as raw materials is a conventional technical means in the prior art;

[0013] (2) ZIF-67 material and ruthenium salt of step (1) are added to the carbon source solution, and after sufficient mixing, the residual bubbles in the solution are removed to obtain a mixed solution. The ruthenium salt provides noble metal ruthenium, which replaces Pt to reduce cost and solve the problem of Pt poisoning;

[0014] (3) The solvent in the mixed solution of step (2) is completely evaporated to obtain a ruthenium salt / ZIF-67@carbon source aerogel. After the ZIF-67 material, ruthenium salt and carbon source are fully mixed, the ZIF-67 material and ruthenium salt are stably and uniformly distributed in the aerogel, and no aggregation or other phenomena occur, thereby ensuring the uniform adhesion of ruthenium and cobalt in the aerogel.

[0015] (4) placing the ruthenium salt / ZIF-67@carbon source aerogel of step (3) in a reducing atmosphere, first reducing at 200-300℃ for 3-5h in the reducing atmosphere to make the ruthenium salt reduced to disordered ruthenium nanoparticles; then carbonizing at 600-800℃ for 4-7h in an inert atmosphere to obtain a nitrogen-doped ruthenium-cobalt-carbon material, and in use, the nitrogen-doped ruthenium-cobalt-carbon material can be crushed.

[0016] Preferably, the cobalt salt in step (1) is selected from cobalt nitrate hexahydrate, cobalt chloride or cobalt sulfate, and the molar ratio of the cobalt salt to 2-methylimidazole is 1:14-16, research shows that the ZIF-67 material obtained under this molar ratio is nanoscale, and nanoscale cobalt doping is obtained by calcining the nanoscale ZIF-67.

[0017] Preferably, the ZIF-67 material in step (1) is prepared according to the following steps:

[0018] S1, dissolving the cobalt salt in methanol to obtain solution A;

[0019] dissolving 2-methylimidazole in methanol to obtain solution B;

[0020] S2, adding solution B to solution A and mixing uniformly, after standing at room temperature for 24-36h, washing, centrifuging and drying to obtain the ZIF-67 material.

[0021] Preferably, in the carbon source solution of step (2), the carbon source is selected from sodium alginate or potassium alginate; the ruthenium salt is selected from ruthenium chloride, ruthenium acetylacetone, ruthenium acetate, ruthenium dicyclopentadiene, potassium ruthenate, ammonium chlororuthenate, sodium chlororuthenate or potassium chlororuthenate.

[0022] Preferably, in step (2), the mass ratio of the carbon source, the ZIF-67 material and the ruthenium salt is 1:0.3-0.5:0.8-1.

[0023] Preferably, the solvent evaporation method in step (3) is freeze-drying method.

[0024] Preferably, in step (4), the reducing atmosphere is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:10.

[0025] The application also protects the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared by the above preparation method.

[0026] The application also protects the application of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material in preparing a direct methanol fuel cell cathode catalyst.

[0027] Compared with the prior art, the application has the following beneficial effects:

[0028] 1、The application first uses cobalt nitrate hexahydrate and 2-methyl imidazole as raw materials to prepare the MOF material ZIF-67, the ZIF-67 material is a purple precipitate, the ZIF-67 material is a kind of porous metal organic framework material, which is a material with a pore structure assembled by Co ions and multi-dentate organic ligands containing coordination atoms such as oxygen and nitrogen, has the advantages of large specific surface area, regular pore structure, pore order, controllable pore size, rich metal sites, simple nano structure design, etc., when the ZIF-67 material is carbonized at high temperature in an inert atmosphere, 2-methyl imidazole will be carbonized to form a carbon skeleton, and cobalt elements will be reduced to metal cobalt nanoparticles dispersed in the skeleton of the carbon material, so that the ZIF-67 material directly provides nitrogen doping and the attachment and compounding of Co nanoparticles after calcination.

[0029] 2、The application mixes the ZIF-67 material, ruthenium salt and carbon source, at this time the carbon source is used as support, so that the ruthenium salt and the ZIF-67 material are uniformly distributed in the carbon source and form a gel; the application disperses the platinum group metal ruthenium and the transition metal cobalt in the carbon carrier, after the solvent is evaporated and dried, it is placed in a reducing atmosphere, the ruthenium salt is first reduced to disordered ruthenium nanoparticles at low temperature, and then carbonized at high temperature in an inert atmosphere, in the high-temperature carbonization, the ZIF-67 provides nitrogen doping, cobalt compounding and a carbon skeleton, and the carbon source forms a porous carbon after calcination, the porous carbon provides a large specific surface area of cross-linked pore structure, so that the platinum group metal ruthenium and the transition metal cobalt are stably attached to the porous carbon.

[0030] 3、The application solves the problem that the exchange current density of the Ru-based catalyst is far lower than that of Pt / C by using nitrogen-doped carbon material and compounding the platinum group metal ruthenium and the transition metal cobalt with the carbon material; in addition, the application uses a Pt-free material to prepare a high-efficiency fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material, which reduces the production cost and overcomes the problem of Pt electrode poisoning by CO existing in fuel gas;

[0031] The carbon material of the application is doped with nitrogen atoms and is compounded with ruthenium and cobalt, the nitrogen atoms provide more electronic active sites, the electronic transmission speed of the porous carbon is improved, the porous carbon provides a large specific surface area of cross-linked pore structure, so that the nano ruthenium and cobalt are stably attached to the porous carbon; the valence bond formed between cobalt and carbon can improve the interaction between cobalt and carbon, further improve the activity and stability of the catalyst, and then improve the catalytic performance of the Ru / C material. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The oxygen reduction kinetic polarization curve diagram of Example 2, Comparative Example 1 and commercial 20wt.% Pt / C catalyst as a working electrode of the application respectively;

[0033] Figure 2A chronoamperometric curve of a methanol response of a commercial 20wt.% Pt / C catalyst;

[0034] Figure 3 A plot of oxygen reduction kinetic polarization curves of a fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material sample of Example 2 and a commercial 20wt.% Pt / C catalyst before and after 2000 cycles, respectively; wherein, (a) is the plot of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material sample of Example 2; (b) is the plot of the commercial 20wt.% Pt / C catalyst sample. DETAILED DESCRIPTION

[0035] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of the present application is not limited to the specific embodiments. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts fall within the scope of the present application. The experimental methods described in the embodiments of the present application are conventional methods unless otherwise specified.

[0036] Example 1

[0037] The preparation method of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material comprises the following steps:

[0038] (2) ZIF-67 material is prepared by using cobalt nitrate hexahydrate and 2-methylimidazole as raw materials;

[0039] The mass ratio of cobalt nitrate hexahydrate to 2-methylimidazole is 1:8;

[0040] S1, dissolve cobalt nitrate hexahydrate in methanol to obtain solution A; dissolve 2-methylimidazole in methanol to obtain solution B;

[0041] S2, add solution B to solution A and mix uniformly, then stand at room temperature for 36 hours, and then wash, centrifuge and dry to obtain ZIF-67 material;

[0042] (3) add the ZIF-67 material of step (1) and ruthenium chloride to the sodium alginate solution, mix thoroughly, and then remove the residual bubbles in the solution to obtain a mixed solution;

[0043] The mass ratio of sodium alginate, ZIF-67 material and ruthenium chloride is 1:0.5:0.8;

[0044] (3) completely evaporate the solvent in the mixed solution of step (2) by freeze-drying to obtain a ruthenium salt / ZIF-67@carbon source aerogel;

[0045] (4) placing the ruthenium salt / ZIF-67@carbon source aerogel of step (3) in a reducing atmosphere, first reducing at 200 DEG C for 5h in a reducing atmosphere, and then carbonizing at 800 DEG C for 4h in an inert atmosphere to obtain a nitrogen-doped ruthenium-cobalt-carbon material;

[0046] The reducing atmosphere is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:10.

[0047] Example 2

[0048] The preparation method of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material comprises the following steps:

[0049] (1) preparing a ZIF-67 material with cobalt chloride and 2-methyl imidazole as raw materials;

[0050] The mass ratio of cobalt chloride to 2-methyl imidazole is 1:5.

[0051] S1, dissolving cobalt chloride in methanol to obtain solution A; dissolving 2-methyl imidazole in methanol to obtain solution B;

[0052] S2, adding solution B to solution A and mixing uniformly, standing at room temperature for 30h, and then washing, centrifuging and drying to obtain a ZIF-67 material;

[0053] (2) adding the ZIF-67 material of step (1) and ruthenium acetylacetone to a sodium alginate solution, mixing thoroughly, and removing the residual bubbles in the solution to obtain a mixed solution;

[0054] The mass ratio of sodium alginate, ZIF-67 material and ruthenium acetylacetone is 1:0.4:0.9.

[0055] (3) completely evaporating the solvent in the mixed solution of step (2) by freeze-drying to obtain a ruthenium salt / ZIF-67@carbon source aerogel;

[0056] (4) placing the ruthenium salt / ZIF-67@carbon source aerogel of step (3) in a reducing atmosphere, first reducing at 250 DEG C for 4h in a reducing atmosphere, and then carbonizing at 700 DEG C for 5h in an inert atmosphere to obtain a nitrogen-doped ruthenium-cobalt-carbon material;

[0057] The reducing atmosphere is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:10.

[0058] Example 3

[0059] The preparation method of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material comprises the following steps:

[0060] (1) preparing a ZIF-67 material with cobalt sulfate and 2-methyl imidazole as raw materials;

[0061] The mass ratio of cobalt sulfate to 2-methyl imidazole is 1:3;

[0062] S1, dissolve cobalt sulfate in methanol to obtain solution A; dissolve 2-methyl imidazole in methanol to obtain solution B;

[0063] S2, add solution B to solution A and mix uniformly, stand at room temperature for 24 h, then wash, centrifuge and dry to obtain ZIF-67 material;

[0064] (2) add the ZIF-67 material of step (1), sodium chlororuthenate to the potassium alginate solution, mix thoroughly, and remove the residual bubbles in the solution to obtain a mixed solution;

[0065] The mass ratio of potassium alginate, ZIF-67 material, and sodium chlororuthenate is 1:0.3:1;

[0066] (3) completely evaporate the solvent in the mixed solution of step (2) by freeze-drying to obtain a ruthenium salt / ZIF-67@carbon source aerogel;

[0067] (4) place the ruthenium salt / ZIF-67@carbon source aerogel of step (3) in a reducing atmosphere, first reduce at 300°C for 3 h in a reducing atmosphere, and then carbonize at 600°C for 7 h in an inert atmosphere to obtain a nitrogen-doped ruthenium-cobalt-carbon material;

[0068] The reducing atmosphere is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:10.

[0069] Comparative Example 1

[0070] The preparation method of the ruthenium-carbon material comprises the following steps:

[0071] (1) add acetylacetone ruthenium to a sodium alginate solution, mix thoroughly, and remove the residual bubbles in the solution to obtain a mixed solution;

[0072] The mass ratio of sodium alginate to acetylacetone ruthenium is 1:0.9;

[0073] (2) completely evaporate the solvent in the mixed solution of step (1) by freeze-drying to obtain a ruthenium salt@carbon source aerogel;

[0074] (3) place the ruthenium salt@carbon source aerogel of step (2) in a reducing atmosphere, first reduce at 250°C for 4 h in a reducing atmosphere, and then carbonize at 700°C for 5 h in an inert atmosphere to obtain a ruthenium-carbon material;

[0075] The reducing atmosphere is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:10.

[0076] The fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared in Example 1-3 has high catalytic activity and stability. The following is a comparative study of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared in Example 2, the ruthenium-carbon material of Comparative Example 1, and the commercial 20wt.% Pt / C catalyst. The specific research methods and results are shown below.

[0077] Catalytic performance test:

[0078] The electrochemical test was performed on a CHI750E electrochemical workstation produced by Shanghai Chenhua Company, and a three-electrode system was used for testing. A platinum wire was used as the counter electrode, an Ag / AgCl electrode was used as the reference electrode, and a glassy carbon electrode loaded with the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material was used as the working electrode. The working electrode, reference electrode, and counter electrode were placed in an oxygen-saturated 0.1 mol / L KOH solution for scanning test.

[0079] The glassy carbon electrode loaded with the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material was prepared according to the following steps: the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material and 10 μL of 5% Nafion ethanol solution were added to 1 mL of anhydrous ethanol, and ultrasonic dispersion was performed for 30 min to fully mix the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material and Nafion to form an ink solution. The ink solution was evenly dropped onto the glassy carbon electrode and dried to obtain the glassy carbon electrode loaded with the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material. Calculation showed that the loading amount of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material was 100 μg / cm -2 .

[0080] The test used linear voltammetry, and the oxygen reduction kinetic polarization curve of the catalyst was recorded at a scanning rate of 5 mV / s between -0.8 and 0.1 V at a speed of 1600 r / min. The methanol tolerance of the catalyst was tested by chronoamperometry at a constant voltage of -0.4 V, and the current response curve of the electrode before and after the addition of methanol to the electrolyte solution was recorded.

[0081] Figure 1 The catalytic activity of the catalyst (fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material), the catalyst of Comparative Example 1 (ruthenium-carbon material), and the commercial 20wt.% Pt / C catalyst was compared. The results showed that in an alkaline medium, at a potential of -0.4 V, the current density of the catalyst of the present application was 5.14 mAcm -2, and in the basic medium, the relationship of the oxygen reduction electrocatalytic activity is: fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material > commercial 20wt.% Pt / C catalyst > ruthenium-carbon material; based on this, the subsequent experiment directly uses the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material of the application and the commercial 20wt.% Pt / C catalyst for comparison.

[0082] Figure 2 The i-t stability test curve of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared in Example 2 and the commercial 20wt.% Pt / C catalyst. As shown in the figure, under the condition of constant voltage of-0.4V, in 0.1mol / L KOH aqueous solution, the current value of the working electrode coated with the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material is continuously worked for 1000 seconds, and the current value is reduced by about 5%, while the current value of the commercial Pt / C is reduced more obviously, about 30%, which shows that the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared by the application has excellent stability in methanol and is not easy to be poisoned by CO.

[0083] Figure 3 The durability curve of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared in Example 2 and the commercial Pt / C after cyclic voltammetry scanning at a rate of 5mV / s in the potential range of-0.8~0.1V (vs. RHE) for 2000 times is studied; from Figure 3 It can be known that the E 1 / 2 potentials of the working electrode coated with the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material and the working electrode coated with the commercial Pt / C are both negatively shifted after 2000 cycles, and compared with figure (a) and figure (b), the distance of the negative shift of the two is obviously different, and the E 1 / 2 potential of the commercial Pt / C is obviously higher than that of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material of the application, which shows that the catalytic stability of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material of the application is better.

[0084] Obviously, those skilled in the art can make various modifications and variations to the application without departing from the spirit and scope of the application. Thus, if these modifications and variations of the application belong to the scope of the claims of the application and the equivalent technologies thereof, the application also intends to include these modifications and variations. The above-described examples are only the preferred examples for fully illustrating the application, and the protection scope is not limited thereto.

Claims

1. A method for preparing a nitrogen-doped ruthenium-cobalt-carbon material for a cathode electrocatalyst of a fuel cell, characterized in that, The method comprises the following steps: (1) preparing ZIF-67 material by using cobalt salt and 2-methyl imidazole as raw materials; (2) adding ZIF-67 material of step (1) and ruthenium salt into a carbon source solution, removing residual bubbles in the solution after sufficient mixing to obtain a mixed solution; (3) evaporating the solvent in the mixed solution of step (2) to obtain ruthenium salt / ZIF-67@carbon source aerogel; (4) placing the ruthenium salt / ZIF-67@carbon source aerogel of step (3) in a reducing atmosphere, reducing at 200-300 DEG C in the reducing atmosphere for 3-5 h, and then carbonizing at 600-800 DEG C in an inert atmosphere for 4-7 h to obtain nitrogen-doped ruthenium-cobalt-carbon material; The carbon source in the carbon source solution of step (2) is selected from sodium alginate or potassium alginate; The mass ratio of the carbon source, ZIF-67 material and ruthenium salt in step (2) is 1:0.3-0.5:0.8-1.

2. The method for preparing nitrogen-doped ruthenium-cobalt carbon material for fuel cell cathode electrocatalyst according to claim 1, characterized in that, The cobalt salt in step (1) is selected from cobalt nitrate hexahydrate, cobalt chloride or cobalt sulfate, and the molar ratio of the cobalt salt to 2-methyl imidazole is 1:14-16.

3. The method for preparing nitrogen-doped ruthenium-cobalt carbon material for fuel cell cathode electrocatalyst according to claim 1, characterized in that, The ZIF-67 material in step (1) is prepared according to the following steps: S1, dissolving cobalt salt in methanol to obtain solution A; dissolving 2-methyl imidazole in methanol to obtain solution B; S2, adding solution B into solution A and mixing uniformly, standing at room temperature for 24-36 h, and then washing, centrifuging and drying to obtain ZIF-67 material.

4. The method for preparing nitrogen-doped ruthenium-cobalt carbon material for fuel cell cathode electrocatalyst according to claim 1, characterized in that, The ruthenium salt is selected from ruthenium chloride, ruthenium acetate, potassium ruthenate, ammonium chlororuthenate, sodium chlororuthenate or potassium chlororuthenate.

5. The method for preparing nitrogen-doped ruthenium-cobalt carbon material for fuel cell cathode electrocatalyst according to claim 1, characterized in that, The evaporation method of the solvent in step (3) is freeze-drying method.

6. The method for preparing nitrogen-doped ruthenium-cobalt carbon material for fuel cell cathode electrocatalyst according to claim 1, characterized in that, The reducing atmosphere in step (4) is a mixed gas composed of hydrogen and argon, and the volume ratio of hydrogen to argon is 1:

10.

7. A fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material prepared by the preparation method of any one of claims 1-6.

8. Use of the fuel cell cathode electrocatalyst nitrogen-doped ruthenium-cobalt-carbon material of claim 7 in preparing a direct methanol fuel cell cathode catalyst.

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