▎ 摘　　要

A graphene oxide (GO) nanosheet with epoxy groups was prepared by exfoliating the graphite oxide. The free standing membrane of the GO nanosheet with epoxy groups was used for water purification, which showed higher water selectivity from NaCl aqueous solution compared with conventional GO membrane with various oxygen functional groups such as carboxyl, hydroxyl, and epoxy groups, indicating that the epoxy groups on the GO nanosheet suppress the permeation of ions.