▎ 摘　　要

NOVELTY - Preparing nitrogen-doped graphene-supported core-shell copper-carbon composite catalyst involves adding nitrogen-doped reduced graphene oxide to the mixed solution of N,N-dimethylformamide and ethanol to fully disperse, then adding Copper(II) Nitrate Trihydrate (Cu(NO3)2.3H2O) and continue stirring until it is completely dissolved to get mixture. The benzimidazole is dissolved in a mixed solution of N,N-dimethylformamide and ethanol and stirring to dissolve to obtain benzimidazole solution, and dissolving trimesic acid in a mixture of N,N-dimethylformamide and ethanol and mixing under stirring in the mixed solution until it dissolves to obtain trimellitic acid solution. The concentration of Cu(NO3)2.3H2O in the mixed solution is 2.5mg/mL-3.0mg/mL. The mass ratio of Cu(NO3)2.3H2O to nitrogen-doped reduced graphene oxide in the mixed solution is 1:(0.1-0.3). USE - Method for preparing nitrogen-doped graphene-supported core-shell copper-carbon composite catalyst for carbon dioxide based electrocatalytic production of formic acid. ADVANTAGE - The method enables to prepare nitrogen-doped graphene-supported core-shell copper-carbon composite catalyst, which solve the problems of poor product selectivity and low stability of the existing porous carbon-supported metal catalyst. DETAILED DESCRIPTION - Preparing nitrogen-doped graphene-supported core-shell copper-carbon composite catalyst involves adding nitrogen-doped reduced graphene oxide to the mixed solution of N,N-dimethylformamide and ethanol to fully disperse, then adding Copper(II) Nitrate Trihydrate (Cu(NO3)2.3H2O) and continue stirring until it is completely dissolved to get mixture. The benzimidazole is dissolved in a mixed solution of N,N-dimethylformamide and ethanol and stirring to dissolve to obtain benzimidazole solution, and dissolving trimesic acid in a mixture of N,N-dimethylformamide and ethanol and mixing under stirring in the mixed solution until it dissolves to obtain trimellitic acid solution. The concentration of Cu(NO3)2.3H2O in the mixed solution is 2.5mg/mL-3.0mg/mL. The mass ratio of Cu(NO3)2.3H2O to nitrogen-doped reduced graphene oxide in the mixed solution is 1:(0.1-0.3). The concentration of the benzimidazole in the benzimidazole solution is 10 mg/mL to 15 mg/mL; and concentration of trimesic acid in the trimesic acid solution is 1.0 mg/mL to 1.5 mg/mL. The mixed solution is mixed with the benzimidazole solution and stir until it appears bright blue, then add the trimellitic acid solution to it and continue mixing and stirring to obtain the precursor solution, and transferring the precursor solution to polytetrafluoroethylene in a stainless steel reaction kettle lined with ethylene, and hydrothermal reaction is carried out for 5-8 hours at a constant temperature of 80-100 degrees C to obtain a CuMOF precursor supported by nitrogen-doped graphene. The mass ratio of Cu(NO3)2.3H2O to benzimidazole in the precursor solution is 1:(3-5), and weight ratio of Cu(NO3)2.3H2O and trimellitic acid in the precursor solution is 1:(0.7-1.0). The cleaning and drying are carried out after centrifuging the CuMOF precursor loaded on nitrogen-doped graphene, for multiple times with absolute ethanol and then drying in a vacuum drying oven to obtain dried product. The dried product os placed in a tube furnace and passed in high-purity argon (Ar) gas, and increasing the temperature to 700 degrees C at a heating rate of 1-5 degrees C/minute and calcined at 700-1000 degrees C for 3-8 hours to obtain desired product.