▎ 摘　　要

NOVELTY - Preparing layered composite material involves preparing graphene quantum dots which is prepared by first preparing graphene oxide by Hummers method, then ultrasonically dispersing graphene oxide in N,N-dimethylformamide. The material ratio of graphene oxide and N,N-dimethylformamide is 0.2-0.4g:20 mL to form homogenous mixture. The resulting mixture is then transferred to reaction vessel and maintained at 180-220 degrees C for 6-10 hours, cooling, 0.22 micrometer microfiltration is performed and evaporating at 80-100 degrees C to obtain graphene quantum dots. USE - Method for preparing layered composite material. ADVANTAGE - The method enables to prepare layered composite material in simple manner and is cost effective, short production period is short, has large specific surface area, high chemical stability and excellent electrochemical performance. It has highest specific capacitance is 400 Faraday/g, circulating for 1000 times, still keeps the original 93% than capacitor and potential application value. DETAILED DESCRIPTION - Preparing layered composite material involves preparing graphene quantum dots which is prepared by first preparing graphene oxide by Hummers method, then ultrasonically dispersing graphene oxide in N,N-dimethylformamide, The material ratio of graphene oxide and N,N-dimethylformamide is 0.2-0.4g:20 mL to form homogenous mixture. The resulting mixture is then transferred to reaction vessel and maintained at 180-220 degrees C for 6-10 hours, cooling, 0.22 micrometer microfiltration is performed and evaporating at 80-100 degrees C to obtain graphene quantum dots. The precursor solution of cobalt nitrate solution, graphene quantum dot solution and deionized water are weighed. The volume ratio of the precursor solution of cobalt nitrate solution, graphene quantum dot solution and deionized water is 10 to 20:4:1 milliliter. The precursor solution of cobalt nitrate solution, graphene quantum dot solution and deionized water are mixed then mixture is stirred uniformly, transferred into water-heating kettle, and reacted in oven at 160-200 degrees C for 12-24 hours and filter, wash and dry to obtain layered composite material.