Graphene-based membranes, consisting of two-dimensional (2D) graphene oxide (GO) or reduced graphene oxide (rGO) nanosheets, have recently attracted increasing attention in liquid and gas separation. The nanochannels of these membranes, formed between 2D GO or rGO nanosheets, allow gases ,water and ions with smaller sizes than those of the channels to permeate, while blocking all other larger species. Although the lamellar GO and rGO membranes have been intensively investigated, the mass transport through these membranes has not yet been fully understood, particularly for rGO membranes which have extremely narrowed interlayer d-spacing (with a size close to that of graphite) which theoretically cannot provide effective nanochannels for fluid permeation. Some studies demonstrated intrinsic defects (holes in the nanosheets, normally with the size over 1 nm) in rGO nanosheets could be responsible for mass transport in these membranes. This might be true for ultrathin rGO membrane. The intrinsic defects should not play the major role in thick rGO membranes given the chance of forming interconnected channels by these defects is very low. Our new experimental and simulation results reveal that the intrinsic nanowrinkles in GO and rGO membranes, with uniform diameter of 2-3 nm, act as fast channels for water permeation. These new insights may throw light upon in-depth understanding in mass transport mechanism of the graphene-based membranes.

Graphane based membranes: Water transport

255th National Meeting (2018)

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