▎ 摘　　要

NOVELTY - Preparation of nitrogen-doped hierarchical porous monolithic carbon material involves dispersing (i) melamine nanosponges in a graphene oxide dispersion, soaking for 20-60 minutes, sealing and freeze-drying to obtain graphene oxide/melamine nanosponges (GO/MS), dispersing (ii) zinc nitrate in a methanol solution and mixing evenly, adding polyvinylpyrrolidone, stirring for 30 minutes to obtain a solution (a), dispersing dimethylimidazole in a methanol solution and mixing evenly to obtain a solution (b), immersing the dry graphene oxide/melamine nanosponges in the solution (a), ultrasonically-processing, quickly pouring the solution (b) into the solution (a) with GO/MS, ultrasonically-processing, maintaining for 12-24 hours, drying at room temperature, rinsing with deionized water and continuously drying to obtain zeolitic imidazolate framework-8/graphene oxide/melamine nanosponges, and carbonizing (iii) the zeolitic imidazolate framework-8/graphene oxide/melamine nanosponges. USE - Preparation of nitrogen-doped hierarchical porous monolithic carbon material used for forming positive electrode for supercapacitor (all claimed). ADVANTAGE - The method enables simple and reliable preparation of nitrogen-doped hierarchical porous monolithic carbon material having improved electrochemical performance. DETAILED DESCRIPTION - Preparation of nitrogen-doped hierarchical porous monolithic carbon material involves dispersing (i) melamine nanosponges in a graphene oxide dispersion having a concentration of 0.5-2 mg/mL, soaking for 20-60 minutes to complete wetting, sealing and freeze-drying to obtain graphene oxide/melamine nanosponges, dispersing (ii) zinc nitrate in a methanol solution and mixing evenly, adding an appropriate amount of polyvinylpyrrolidone, stirring for 30 minutes until the solution is evenly mixed to obtain a solution (a), dispersing dimethylimidazole in a methanol solution and mixing evenly to obtain a solution (b), in which the mass ratio of zinc nitrate with respect to polyvinylpyrrolidone is 29.7:1 to 2.97:1, and the mass ratio of zinc nitrate with respect to dimethylimidazole is 3.6:1 to 1:3.6, immersing the dry graphene oxide/melamine nanosponges in the solution (a), ultrasonically-processing until it is completely wetted, quickly pouring the solution (b) into the solution (a) with GO/MS, ultrasonically-processing, maintaining for 12-24 hours, drying at room temperature, rinsing with deionized water and continuously drying to obtain zeolitic imidazolate framework-8/graphene oxide/melamine nanosponges, and carbonizing (iii) the zeolitic imidazolate framework-8/graphene oxide/melamine nanosponges under argon atmosphere at 800-1000 degrees C for 1-4 hours.