Effects of Charging and Perpendicular Electric Field on Graphene Oxide

Abstract

We present a first-principles study of the effects of charging, electric field on the oxidation/deoxidation of graphene oxide consisting of epoxy and hydroxly groups. We first determined the proper basis set which prevents the spurious spilling of electrons of graphene oxide, when negatively charged or exerted by perpendicular electric field and treated with periodic boundary conditions. Applied perpendicular electric field to graphene surface is provided side specific functionalization. We showed that the bonds between oxygen and graphene are weakened under applied electric field. For specific values of excess charge or perpendicular electric field, oxygen atom moves to the top site from bridge site which is normally absorbed in equilibrium. Individually adsorbed oxygen atoms cannot form oxygen molecules due to an energy barrier. This energy barrier is dramatically weakened, when negatively charged or exerted by an electric field. Beside the epoxy groups, hydroxyl groups have an important role of oxidation/deoxidation of graphene oxide. Charging and perpendicular electric field mediates the reduction of graphene oxide through the formation of H2O and H2O2. Our results explain the role of external effects to the reduction of graphene oxide.