Control of Edge/In-Plane Interactions toward Robust, Highly Proton Conductive Graphene Oxide Membranes.

Graphene oxide (GO) membrane, bearing well-aligned interlayer nanochannels and well-defined physicochemical properties, promises fast proton transport. However, the deficiency of proton donor groups on the basal plane of GO and weak interlamellar interactions between the adjacent nanosheets often cause the low proton conduction capability and poor water stability. Herein, we incorporate the sulfonated graphene quantum dots (SGQD) into graphene oxide (GO) membrane to solve the above dilemma via synergistically control the edge electrostatic interaction and in-plane π-π interaction of SGQD with GO nanosheets. SGQD with three different kinds of electron-withdrawing groups are employed to modulate the edge electrostatic interactions and improve the water swelling resistant property of GO membranes. Meanwhile, SGQD with abundant proton donor groups assemble on the sp2 domain of GO via in-plane π-π interaction and confer the GO membranes with low energy-barrier proton transport channels. As a result, the GO membrane achieves enhanced proton conductivity of 324 mS cm-1, maximum power density of 161.6 mW cm-2, and superior water stability when immersed into water for one month. This study demonstrates a strategy for independent manipulation of conductive function and non-conductive function to fabricate high-performance proton exchange membranes.