(124a) Self-Assembly: A Facile Way of Forming Ultrathin, High-Performance Graphene Oxide Membranes for Water Purification

Single-layer graphene oxide (SLGO) is emerging as a new-generation membrane material for high-flux, high-selectivity water purification, owing to its favorable 2-D morphology that allows facile fabrication of ultrathin membranes with sub-nanometer interlayer channels. However, reliable and precise molecular sieving performance still necessarily depends on thick graphene oxide (GO) deposition which usually leads to low water flux. This trade-off between selectivity and flux significantly impedes the development of ultrathin GO membranes. In this work, we demonstrate that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control. We find GO membranes, prepared by slow deposition of SLGO flakes, exhibit considerably improved salt rejection, while counterintuitively having 2.5~4 times higher water flux than that of membranes prepared by fast deposition. This finding has extensive implications of designing/tuning interlayer nanostructure of ultrathin GO membranes by simply controlling SLGO deposition rate, and thus may greatly facilitate their development for high flux, high selectivity water purification.