Method for preparing self-supporting Co / MoN composite three-dimensional graphene-like carbon material

Abstract

The invention discloses a method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, which specifically comprises the following steps: soaking the self-supporting three-dimensional graphene-like carbon material in a solution containing a molybdenum compound and a cobalt compound, taking out the self-supporting three-dimensional graphene-like carbon material after soaking, drying the self-supporting three-dimensional graphene-like carbon material, and calcining the self-supporting three-dimensional graphene-like carbon material in an ammonia / inert gas atmosphere to obtain the self-supporting Co / MoN composite three-dimensional graphene-like carbon material. Based on high activity provided by the Co / MoN nanoparticles and high conductivity provided by the three-dimensional graphene-like carbon material, high capacity, high-rate discharge capacity and good cycle stability of the lithium-sulfur battery can be realized.

Description

Technical Field

[0001] The present invention relates to a method for preparing a self - supported Co / MoN composite three - dimensional graphene - like carbon material. Background Art

[0002] Lithium - sulfur batteries have the potential to replace lithium - ion batteries in the energy storage field due to their high theoretical energy density of up to 2600 Wh / kg and low cost. However, there are still some obstacles in their practical applications, mainly including the following three problems: First, the sulfur cathode is insulating, resulting in hindered electron conduction during charge and discharge, which is not conducive to high - rate performance; second, polysulfide dissolves and diffuses during charge and discharge, leading to sulfur loss and the growth of lithium dendrites, ultimately causing battery capacity loss and safety problems; third, the volume of the sulfur cathode changes significantly during cycling, resulting in the detachment of the binder and conductive agent.

[0003] When metal - free self - supported three - dimensional graphene - like carbon materials are applied to the lithium - sulfur battery cathode, although the carbon matrix can be transformed from non - polar to polar by heteroatom doping, the adsorption effect on polar polysulfides is still limited, and it is difficult to effectively anchor and transform polysulfides. Therefore, to further improve the cycle stability and specific capacity, it is necessary to find a suitable composite material. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a method for preparing a self - supported Co / MoN composite three - dimensional graphene - like carbon material. When the material prepared by this method is used as the cathode of a lithium - sulfur battery, on the one hand, it can effectively solve the problem of hindered electron conduction during charge and discharge caused by the insulation of the sulfur cathode, thereby improving the high - rate performance of the lithium - sulfur battery; on the other hand, it can inhibit the dissolution and diffusion of polysulfide during charge and discharge, reduce sulfur loss, and prevent the growth of lithium dendrites, thus effectively avoiding battery capacity loss and enhancing the stability of the electrode structure. When the lithium - sulfur battery is charged and discharged at a constant current at 0.5C and 1C rates, it has good specific capacity, rate performance, and cycle stability performance.

[0005] Technical Solution: The method for preparing a self - supported Co / MoN composite three - dimensional graphene - like carbon material according to the present invention is specifically as follows: Immerse the self - supported three - dimensional graphene - like carbon material in a solution containing molybdenum compounds and cobalt compounds, take it out and dry it after immersion, and then calcine it in an ammonia / inert gas atmosphere to obtain the self - supported Co / MoN composite three - dimensional graphene - like carbon material.

[0006] Among them, the self - supported three - dimensional graphene - like carbon material used in the present invention is prepared by the method described in the application number 2024101550074.

[0007] Among them, the molybdenum compound is ammonium heptamolybdate; the cobalt compound is at least one of cobalt(II) chloride hexahydrate, cobalt(II) nitrate hexahydrate, cobalt(II) acetate, or cobalt phthalocyanine.

[0008] Among them, the molar ratio of the molybdenum compound to the cobalt compound is 0.5 - 1:1.

[0009] Among them, the solvents selected for the solution are water and N,N-dimethylformamide.

[0010] Among them, the drying temperature is 70 - 80 °C.

[0011] Among them, the inert gas is Ar or N2, and the flow rate ratio of the inert gas to the ammonia gas is 1 - 3:1.

[0012] Among them, the heating rate is 5 - 20 °C / min, the calcination temperature is 500 - 750 °C, and the calcination duration is 0.5 - 2 h. If the calcination temperature is too low, it will be unfavorable for the formation of MoN and further sufficient N doping of the carbon matrix, resulting in a low battery capacity; if the calcination time is too long, excessive N doping will damage the structural integrity of the carbon matrix, which is not conducive to the cycle stability of the battery.

[0013] Among them, the self-supporting Co / MoN composite three-dimensional graphene-like carbon material is composed of a three-dimensional graphene-like carbon material and Co / MoN nanoparticles supported on the three-dimensional graphene-like carbon material.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: In the material prepared by the present invention, on the one hand, the self-supporting three-dimensional carrier can avoid the use of binders and conductive agents between sulfur and the carrier, and on the other hand, it can physically limit the shuttle of polysulfide lithium, effectively prevent the growth of lithium dendrites while reducing sulfur loss, and at the same time can provide a three-dimensional conductive network for sulfur, thereby accelerating electron transfer and improving the rate performance; meanwhile, the nitrogen doping of the carbon matrix and the formed molybdenum nitride can provide abundant N active sites, convert the carbon material from non-polar to polar, promote the chemical bonding between the carbon matrix and polysulfide lithium, further reduce sulfur loss and prevent the growth of lithium dendrites; and the MoN nanoparticles provide double sites for the adsorption and catalysis of polysulfide lithium, and at the same time, by constructing an internal electric field with Co nanoparticles, further synergistically accelerate the transfer of electrons, thereby obtaining a lithium-sulfur battery with good specific capacity, rate performance and cycle stability performance. Description of the Drawings

[0015] Figure 1 XRD pattern of the self-supporting Co / MoN composite three-dimensional graphene-like carbon material prepared in Example 1;

[0016] Figure 2 SEM image of the self-supporting Co / MoN composite three-dimensional graphene-like carbon material prepared in Example 1;

[0017] Figure 3 TEM image of the self-supporting Co / MoN composite three-dimensional graphene-like carbon material prepared in Example 1;

[0018] Figure 4 0.5C cycle performance diagram of lithium-sulfur batteries assembled based on samples of Example 1, Comparative Example 1 and Comparative Example 2;

[0019] Figure 5 Graph showing rate performance of lithium-sulfur batteries assembled based on samples of Example 1, Comparative Example 1, and Comparative Example 2;

[0020] Figure 6 1C cycle performance diagram of lithium-sulfur batteries assembled based on the self-supporting materials of Comparative Example 1 and Comparative Example 2;

[0021] Figure 7 1C cycle performance diagram of lithium-sulfur batteries assembled based on the self-supporting materials of Comparative Examples 3 and 4;

[0022] Figure 8 This is a 1C cycle performance diagram of lithium-sulfur batteries assembled based on the self-supporting materials of Comparative Example 5, Comparative Example 6 and Comparative Example 7. DETAILED DESCRIPTION

[0023] Example 1

[0024] The method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material of the present invention comprises the following steps:

[0025] (1) 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid (mass fraction 98%) were mixed in a corundum crucible, heated and stirred at 210 ° C on a heating table until molten, and then rapidly heated to 540 ° C and kept constant temperature, and the liquid expanded to form carbon foam; the carbon foam was cut into a cylindrical shape with a diameter of 20 mm, and a step carbonization and nitridation process was used to prepare a self-supporting three-dimensional graphene-like carbon material; the step carbonization process was specifically as follows: a heating rate of 10 ° C / min, a final calcination temperature of 1000 ° C, and a total calcination time of 5 h; the nitridation process was a heating rate of 10 ° C / min, a calcination temperature of 1000 ° C, an NH3 flow rate of 100 mL / min, and a calcination time of 2 min;

[0026] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water, then dropwise add 250 μL of a 3 mg / mL aqueous solution of cobalt chloride hexahydrate, and stir evenly; place the self-supporting three-dimensional graphene-like carbon material of step (1) into the mixed solution and fully soak it;

[0027] (3) taking out the soaked self-supporting three-dimensional graphene-like carbon material and drying it at 70°C;

[0028] (4) The dried self-supporting three-dimensional graphene-like carbon material was transferred to a tubular furnace and calcined at 750°C in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar was 1:2) for 0.5 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, which was recorded as sample 1.

[0029] Comparative Example 1

[0030] A method for preparing a self-supporting MoN composite three-dimensional graphene-like carbon material comprises the following steps:

[0031] (1) 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid were mixed in a corundum crucible, heated and stirred at 210 ° C on a heating table until molten, and then rapidly heated to 540 ° C and kept constant temperature, and the liquid expanded to form carbon foam; the carbon foam was cut into a cylindrical shape with a diameter of 20 mm, and a step carbonization and nitridation process was used to prepare a self-supporting three-dimensional graphene-like carbon material; the step carbonization process was specifically as follows: a heating rate of 10 ° C / min, a final calcination temperature of 1000 ° C, and a total calcination time of 5 h; the nitridation process was a heating rate of 10 ° C / min, a calcination temperature of 1000 ° C, an NH3 flow rate of 100 mL / min, and a calcination time of 2 min;

[0032] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water and stir evenly; place the self-supporting three-dimensional graphene-like carbon material of step (1) into the above solution and soak it thoroughly;

[0033] (3) taking out the soaked self-supporting three-dimensional graphene-like carbon material and drying it at 70°C;

[0034] (4) The dried self-supporting three-dimensional graphene-like carbon material was transferred to a tubular furnace and calcined at 750°C in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar was 1:2) for 0.5 h to obtain a self-supporting MoN composite three-dimensional graphene-like carbon material, which was recorded as sample 2.

[0035] Comparative Example 2

[0036] A method for preparing a self-supporting three-dimensional graphene-like carbon material comprises the following steps:

[0037] (1) Mix 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid in a corundum crucible. Heat and stir on a heating platform at 210 °C until it reaches the molten state, then quickly heat to 540 °C and keep it at a constant temperature until the liquid expands to form carbon foam. Cut the carbon foam into cylindrical shapes with a diameter of 20 mm, and prepare a self-supporting three-dimensional graphene-like carbon material using a stepped carbonization and nitridation process. The specific stepped carbonization process is as follows: the heating rate is 10 °C / min, the final calcination temperature is 1000 °C, and the total calcination duration is 5 h. The nitridation process is a heating rate of 10 °C / min, a calcination temperature of 1000 °C, an NH3 flow rate of 100 mL / min, and a calcination duration of 2 min.

[0038] (2) Transfer the self-supporting three-dimensional graphene-like carbon material to a tubular furnace and calcine it in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar is 1:2) at 750 °C for 0.5 h to obtain a self-supporting three-dimensional graphene-like carbon material, denoted as Sample 3.

[0039] Comparative Example 3

[0040] A method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, comprising the following steps:

[0041] (1) Mix 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid in a corundum crucible. Heat and stir on a heating platform at 210 °C until it reaches the molten state, then quickly heat to 540 °C and keep it at a constant temperature until the liquid expands to form carbon foam. Cut the carbon foam into cylindrical shapes with a diameter of 20 mm, and prepare a self-supporting three-dimensional graphene-like carbon material using a stepped carbonization and nitridation process. The specific stepped carbonization process is as follows: the heating rate is 10 °C / min, the final calcination temperature is 1000 °C, and the total calcination duration is 5 h. The nitridation process is a heating rate of 10 °C / min, a calcination temperature of 1000 °C, an NH3 flow rate of 100 mL / min, and a calcination duration of 2 min.

[0042] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water, then add 250 μL of an aqueous cobalt chloride hexahydrate solution with a concentration of 3 mg / mL and stir evenly. Put the self-supporting three-dimensional graphene-like carbon material from step (1) into the mixed solution and soak it thoroughly.

[0043] (3) Take out the soaked self-supporting three-dimensional graphene-like carbon material and dry it at 70 °C.

[0044] (4) Transfer the dried self-supporting three-dimensional graphene-like carbon material to a tubular furnace and calcine it in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar is 1:2) at 500 °C for 0.5 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, denoted as Sample 4.

[0045] Comparative Example 4

[0046] A method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material comprises the following steps:

[0047] (1) 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid were mixed in a corundum crucible, heated and stirred at 210 ° C on a heating table until molten, and then rapidly heated to 540 ° C and kept constant temperature, and the liquid expanded to form carbon foam; the carbon foam was cut into a cylindrical shape with a diameter of 20 mm, and a step carbonization and nitridation process was used to prepare a self-supporting three-dimensional graphene-like carbon material; the step carbonization process was specifically as follows: a heating rate of 10 ° C / min, a final calcination temperature of 1000 ° C, and a total calcination time of 5 h; the nitridation process was a heating rate of 10 ° C / min, a calcination temperature of 1000 ° C, an NH3 flow rate of 100 mL / min, and a calcination time of 2 min;

[0048] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water, then dropwise add 250 μL of a 3 mg / mL aqueous solution of cobalt chloride hexahydrate, and stir evenly; place the self-supporting three-dimensional graphene-like carbon material of step (1) into the mixed solution and fully soak it;

[0049] (3) taking out the soaked self-supporting three-dimensional graphene-like carbon material and drying it at 70°C;

[0050] (4) The dried self-supporting three-dimensional graphene-like carbon material was transferred to a tubular furnace and calcined at 750°C in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar was 1:2) for 2 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, which was recorded as sample 5.

[0051] Comparative Example 5

[0052] A method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material comprises the following steps:

[0053] (1) 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid (mass fraction 98%) were mixed in a corundum crucible, heated and stirred at 210 ° C on a heating table until molten, and then rapidly heated to 540 ° C and kept constant temperature, and the liquid expanded to form carbon foam; the carbon foam was cut into a cylindrical shape with a diameter of 20 mm, and a step carbonization and nitridation process was used to prepare a self-supporting three-dimensional graphene-like carbon material; the step carbonization process was specifically as follows: a heating rate of 10 ° C / min, a final calcination temperature of 1000 ° C, and a total calcination time of 5 h; the nitridation process was a heating rate of 10 ° C / min, a calcination temperature of 1000 ° C, an NH3 flow rate of 100 mL / min, and a calcination time of 2 min;

[0054] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water. Then, add 306 μL of an aqueous cobalt nitrate hexahydrate solution with a concentration of 3 mg / mL dropwise and stir evenly. Immerse the self-supporting three-dimensional graphene-like carbon material from step (1) into the mixed solution fully.

[0055] (3) Take out the immersed self-supporting three-dimensional graphene-like carbon material and dry it at 70 °C.

[0056] (4) Transfer the dried self-supporting three-dimensional graphene-like carbon material into a tubular furnace and calcine it in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar is 1:2) at 750 °C for 0.5 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, denoted as sample 6.

[0057] Comparative Example 6

[0058] A preparation method of a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, comprising the following steps:

[0059] (1) Mix 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid (mass fraction 98%) in a corundum crucible, heat and stir on a heating platform at 210 °C until it becomes a molten state, then quickly heat to 540 °C and keep it at a constant temperature until the liquid expands to form carbon foam. Cut the carbon foam into cylindrical shapes with a diameter of 20 mm, and prepare a self-supporting three-dimensional graphene-like carbon material by using a stepped carbonization and nitridation process. The specific stepped carbonization process is as follows: the heating rate is 10 °C / min, the final calcination temperature is 1000 °C, and the total calcination duration is 5 h. The nitridation process is a heating rate of 10 °C / min, a calcination temperature of 1000 °C, an NH3 flow rate of 100 mL / min, and a calcination duration of 2 min.

[0060] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water. Then, add 186 μL of an aqueous cobalt acetate solution with a concentration of 3 mg / mL dropwise and stir evenly. Immerse the self-supporting three-dimensional graphene-like carbon material from step (1) into the mixed solution fully.

[0061] (3) Take out the immersed self-supporting three-dimensional graphene-like carbon material and dry it at 70 °C.

[0062] (4) Transfer the dried self-supporting three-dimensional graphene-like carbon material into a tubular furnace and calcine it in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar is 1:2) at 750 °C for 0.5 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, denoted as sample 7.

[0063] Comparative Example 7

[0064] A preparation method of a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, comprising the following steps:

[0065] (1) 3 g of p-nitroaniline and 2 mL of concentrated sulfuric acid (mass fraction 98%) were mixed in a corundum crucible, heated and stirred at 210 ° C on a heating table until molten, and then rapidly heated to 540 ° C and kept constant temperature, and the liquid expanded to form carbon foam; the carbon foam was cut into a cylindrical shape with a diameter of 20 mm, and a step carbonization and nitridation process was used to prepare a self-supporting three-dimensional graphene-like carbon material; the step carbonization process was specifically as follows: a heating rate of 10 ° C / min, a final calcination temperature of 1000 ° C, and a total calcination time of 5 h; the nitridation process was a heating rate of 10 ° C / min, a calcination temperature of 1000 ° C, an NH3 flow rate of 100 mL / min, and a calcination time of 2 min;

[0066] (2) Weigh 2.3 mg of ammonium heptamolybdate and dissolve it in 10 mL of water and stir evenly. Place the self-supporting three-dimensional graphene-like carbon material of step (1) into the above solution and soak it thoroughly.

[0067] (3) taking out the soaked self-supporting three-dimensional graphene-like carbon material and drying it at 70°C;

[0068] (4) Weigh 1.8 mg of cobalt phthalocyanine and dissolve it in 10 mL of N,N-dimethylformamide and stir evenly, and immerse the self-supporting three-dimensional graphene-like carbon material in the solution again;

[0069] (5) taking out the soaked self-supporting three-dimensional graphene-like carbon material and drying it at 70°C;

[0070] (6) The dried self-supporting three-dimensional graphene-like carbon material was transferred to a tubular furnace and calcined at 750°C in a mixed atmosphere of NH3 / Ar (the flow rate ratio of NH3 and Ar was 1:2) for 0.5 h to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, which was recorded as sample 8.

[0071] Figure 1 Figure 1 is a typical XRD spectrum of the sample, corresponding to sample 1. The peaks near 31.9°, 36.3°, and 49.2° correspond to MoN (PDF#25-1267), and the peak near 43.7° corresponds to Co (PDF#15-0806). Figure 2 The self-supporting Co / MoN composite three-dimensional graphene-like carbon material obtained in Example 1 is shown, which has a self-supporting three-dimensional structure.

[0072] Figure 3 The self-supporting Co / MoN composite three-dimensional graphene-like carbon material obtained in Example 1 is shown, and Co / MoN nanoparticles are distributed on its surface.

[0073] Battery Assembly: The self-supporting Co / MoN composite three-dimensional graphene-like carbon material (wafer) prepared in Example 1 was combined with 10 μL of 0.5 M Li2S6 solution and directly used as the positive electrode, a lithium metal sheet was used as the negative electrode, LiTFSI was used as the electrolyte, and Celgard 2400 was selected as the separator for battery assembly. The battery assembly of Samples 2 - 5 prepared in Comparative Examples 1 - 4 was the same as that in Example 1.

[0074] Constant current charge-discharge tests were carried out on the lithium-sulfur batteries assembled based on Samples 1 - 3. The test conditions were: constant current charge-discharge at a rate of 0.5C. The results are as Figure 4 shown. When the material of Example 1 was applied to the positive electrode of the lithium-sulfur battery, it had a high initial capacity (1189.7 mAh / g) and good cycle stability (the remaining capacity was 1175.0 mAh / g after 100 cycles). When the material of Comparative Example 1 was applied to the positive electrode of the lithium-sulfur battery, it had a relatively low initial capacity (1005.3 mAh / g) and cycle capacity. When the material of Comparative Example 2 was applied to the positive electrode of the lithium-sulfur battery, its initial capacity (589.9 mAh / g) and cycle capacity were even lower.

[0075] Rate performance tests were carried out on the lithium-sulfur batteries assembled based on Samples 1 - 3. The test conditions were: constant current charge-discharge 5 times at rates of 0.2C, 0.5C, 1C, 2C, 5C, and 0.5C respectively. The results are as Figure 5 shown. When the material of Example 1 was applied to the positive electrode of the lithium-sulfur battery, it exhibited more excellent rate performance (the average discharge capacity at a rate of 5C was 833.3 mAh / g) compared to Comparative Examples 1 and 2.

[0076] Constant current charge-discharge tests were carried out on the lithium-sulfur batteries assembled based on Samples 1 - 2. The test conditions were: constant current charge-discharge at a rate of 1C. The results are as Figure 6 shown. When the material of Example 1 was applied to the positive electrode of the lithium-sulfur battery, it had a high initial capacity (966.6 mAh / g) and good cycle stability (the remaining capacity was 709.7 mAh / g after 500 cycles). When the material of Comparative Example 1 was applied to the positive electrode of the lithium-sulfur battery, it had a relatively low initial capacity (793.7 mAh / g) and poor cycle stability (the remaining capacity was 548.9 mAh / g after 500 cycles).

[0077] Constant current charge-discharge tests were carried out on the lithium-sulfur batteries assembled based on Samples 4 - 5. The test conditions were: constant current charge-discharge at a rate of 1C. The results are as Figure 7 shown. When the material of Comparative Example 3 was applied to the positive electrode of the lithium-sulfur battery, its cycle stability was extremely poor. When the material of Comparative Example 4 was applied to the positive electrode of the lithium-sulfur battery, it had a low initial capacity (839.6 mAh / g) and poor cycle stability (the remaining capacity was 529.9 mAh / g after 500 cycles).

[0078] The lithium-sulfur battery assembled based on Samples 6-8 was tested by constant current charge and discharge. The test conditions were: constant current charge and discharge at a rate of 1C, and the results are as Figure 8 shown. Samples 6-8 prepared based on Comparative Examples 5-7 were applied to the positive electrode of the lithium-sulfur battery. The initial capacities were 760.5 mAh / g, 876.1 mAh / g, and 957 mAh / g respectively, and the remaining capacities after 500 cycles were 583.4 mAh / g, 634.5 mAh / g, and 597.1 mAh / g respectively.

[0079] For the lithium-sulfur battery system with the separator modified by Co / MoN, a constant current charge and discharge test was carried out. The test conditions were: constant current charge and discharge at a rate of 1C, and the remaining capacity after 500 cycles was 554 mAh / g, with a relatively fast performance decay.

Claims

1. A method for preparing a self-supporting Co / MoN composite three-dimensional graphene-like carbon material, characterized in that, Specifically: Immerse the self-supporting three-dimensional graphene-like carbon material in a solution containing molybdenum compounds and cobalt compounds, take it out after immersion, dry it, and then calcine it in an ammonia / inert gas atmosphere to obtain a self-supporting Co / MoN composite three-dimensional graphene-like carbon material.

2. The preparation method according to claim 1, wherein: The molybdenum compound is ammonium heptamolybdate; the cobalt compound is at least one of cobalt(II) chloride hexahydrate, cobalt(II) nitrate hexahydrate, cobalt(II) acetate, or cobalt phthalocyanine.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the molybdenum compound to the cobalt compound is 0.5 - 1:

1.

4. The preparation method according to claim 1, characterized in that: The solvent selected for the solution is water or N,N-dimethylformamide.

5. The preparation method according to claim 1, characterized in that: The drying temperature is 70 - 80 °C.

6. The preparation method according to claim 1, wherein: The inert gas is Ar or N2, and the flow rate ratio of the inert gas to ammonia is 1 - 3:

1.

7. The preparation method according to claim 1, characterized in that: The heating rate is 5 - 20 °C / min, the calcination temperature is 500 - 750 °C, and the calcination duration is 0.5 - 2 h.

8. The preparation method according to claim 1, wherein: The self-supporting Co / MoN composite three-dimensional graphene-like carbon material is composed of a three-dimensional graphene-like carbon material and Co / MoN nanoparticles supported on the three-dimensional graphene-like carbon material.

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