▎ 摘　　要

Membranes with atomic level pores or constrictions are valuable for separation and catalysis. We report a graphene-based membrane with an interlayer spacing of 3.7 angstrom (angstrom). When graphene oxide nanoplates are functionalized and then reduced, the laminated reduced graphene oxide (rGO) nanoplates or functionalized rGO membrane is little affected by an intercalated fluid, and the interlayer spacing of 3.7 angstrom increases only to 4.4 angstrom in wetted state, in contrast to the graphene oxide (GO) membrane whose interlayer spacing increases from 9 angstrom to 13 angstrom in wetted state. When applied to ion separation, this membrane reduced the permeation rate of small ions such as K+ and Na+ by three orders of magnitude compared to the GO membrane.