Graphene oxide membranes: The controlling of transport pathways

Graphene oxide (GO) nanosheets with atomic thickness and tunable physicochemical property have been considering as promising nanobuilding blocks for fabrication of separation membranes with impressive performance. There are two kinds of molecular transport channels in laminar GO membranes, interlayer nanochannels formed by adjacent nanosheets and intrinsic defects/pores/edges of GO nanosheets. It has been dmonstrated that the precise controlling of transport pathways at angstrom level, through reduction, molecule/cation cross-linking, intercalation, physical confinement, electric field adjusting, pore creating, and defect sealing, can greatly improve the separation performance of GO membranes. Herein, we first briefly review the fabrication strategies of GO membranes and then comprehensively disscus the merits and mechanisms of controlling transport pathways of GO membranes for liquid separation applications including static diffusion, pressure-driven filtration, and pervaporation.