Tuning Water Nanofiltration Performance of Few-Layered, Reduced Graphene Oxide Membranes by Oxygen Plasma

Ultrathin, graphene oxide (GO) membranes have shown great potential for water nanofiltration applications. However, due to the difficulties in controlling the intrinsic oxygen-containing functional groups on GO and the swelling of GO interlayers in aqueous solution, it is highly challenging to tune GO membranes’ nanofiltration performance by adjusting their hydrophilicity and interlayer nanochannel size. In this study, oxygen plasma was reported as an effective technique to tune water nanofiltration performance of few-layered, reduced graphene oxide (rGO) membranes, by improving rGO membranes’ hydrophilicity and/or adjusting effective permeation nanochannel/pore sizes. The 5 nm thick GO membranes were fabricated through a layer-by-layer deposition method and subsequently reduced at 220 °C under vacuum. No detectable water permeance (<1.0 L/(m2·h·bar)) under 5 bar pressure drop suggests the high quality of the rGO membranes possibly with very small hydrophobic nanochannels/pores. Exposure to oxygen plasma ...