Stabilizing graphene oxide with complementary nanosheets for robust membranes with high flux

Laminar assembles of graphene oxide (GO) are receiving tremendous attention for their interesting nanofluidic behaviors, but suffer from structural instability and frustrated mass transfer. Herein, we stabilize GO assembles by "complementary nanosheets", and thus obtain highly robust and permeable membranes. Self-exfoliated nanosheets of ionic covalent organic frameworks (iCONs) are intercalated into GO nanosheets. GO and iCONs are physicochemically complementary as they carry opposite charges and hydrogen bonds acceptors and donors, respectively. Upon mixing, they form laminar assembles locked by electrostatic attraction and hydrogen bonds, suppressing swelling in water. Moreover, simulation and experimental results reveal that iCONs expands the interlayer distance and provides additional mass-transport paths. Consequently, the GO/iCONs membranes exhibit ultra-high water permeance up to 11-fold larger than that of pure GO membranes. This work provides a controllable route to stabilize GO assembles, and develops new membranes using complementary two-dimensional structures as building blocks.