▎ 摘　　要

The geometric stability and diffusion property of epoxy groups on graphene sheets are investigated using the first-principles calculations. Compared with the pristine graphene (pri-graphene), the single epoxy group has larger adsorption energy and diffusion barrier on the defective graphene with single vacancy (SV-graphene). Besides, the single O adatom easily be drawn back to the SV site at the diffusion zone and two oxygen adatoms constitute the major feature of oxidized region that the formation of carbonyl and C-O-C group at the SV-graphene. Moreover, the preadsorbed epoxy groups induce the structural distortion of graphene sheet and thus enhance the stability of hydroxyl groups. The results provide valuable guidance on the structural property and formation mechanism of graphene oxide sheet.