▎ 摘　　要

We have carried out a systematic study of quantum capacitance in functionalized graphenes by using DFT calculations. The graphene functionalization has been done by doping with different aliphatic and aromatic molecules and their radicals. The quantum capacitance of functionalized graphenes was estimated from the accurate electronic band structures of the system obtained by using DFT calculations. Our theoretical investigation reveals that aromatic and aliphatic radicals introduce localized density of states near the Fermi level of the functionalized systems, due to a charge localization. As a result, a very high quantum capacitance (>230 mu F/cm(2)) was observed in the system. The effects of atomic dislocation and the vacancy defect on graphene during functionalization has also been incorporated in our investigation. Our study suggests an effective way to synthesize highly efficient graphene-based supercapacitor electrode materials by using aromatic and aliphatic molecule/radical functionalization of graphene.