▎ 摘　　要

We have investigated the quantum capacitance (C-Q) in functionalized graphene modified with ad-atoms from different groups in the periodic table. Changes in the electronic band structure of graphene upon functionalization and subsequently the C-Q of the modified graphene were systematically analyzed using density functional theory (DFT) calculations. We observed that the C-Q can be enhanced significantly by means of controlled doping of N, Cl and P ad-atoms in the pristine graphene surface. These ad-atoms are behaving as magnetic impurities in the system, generating a localized density of states near the Fermi energy which, in turn, increases charge (electron/hole) carrier density in the system. As a result, a very high quantum capacitance was observed. Finally, the temperature dependent study of C-Q for Cl and N functionalized graphene shows that the C-Q remains very high in a wide range of temperatures near room temperature.