▎ 摘　　要

The spontaneous migration and interconversion of oxygen functional groups over graphene sheet have promising high-tech applications. There is a remarkable activation energy barrier against epoxy movement over the graphene. To overcome this energy barrier, different methods have been proposed. In this paper, using first principles calculations, we study the effects of external electric fields and solvents on the activation energy barrier. Our findings show that: (i) epoxy migration on one side of the surface of a graphene sheet is facilitated when a hydroxyl group is adsorbed on the other side of the surface, (ii) applying a perpendicular electric field along the opposite direction of the adsorbed epoxy, weakens the corresponding C-O bonds strength and consequently decreases the activation energy barrier, (iii) the solvents with a larger dielectric constant cause decreasing the activation energy barrier, (iv) under applying an electric field for any given solution, the oxidized graphene is polarized and its solubility increases with decreasing activation energy barrier, and (v) the presence of a single vacancy in the graphene sheet, decreases the barrier. Our work reveals different physical aspects of the solubility of the oxidized graphene in the presence of electric field and vacancy defect on the surface of the graphene sheet.