Engineering stable laminated graphene oxide hybrid membranes via imidazolium cations complexation

The water-induced interlayer spacing (d-spacing) expansion and architecture dissociation risk of graphene oxide (GO)-based membranes are the greatest roadblock to their application in aqueous solutions as molecular or ionic separation barriers. How to engineer stable GO-based membranes in water has attracted much attention from scientific communities. Herein, imidazolium cations were used to complex with GO sheets and build up stable laminated GO-hybrid membranes. It was experimentally confirmed that the complexation between imidazolium cations and GO sheets through π-π, cation-π, and electrostatic interactions, effectively suppressed the d-spacing expansion of GO-hybrid membranes under aqueous condition, which showed high stability in long-time aqueous immersion, regardless of strong acidic and alkaline conditions. Moreover, with the assistance of imidazolium cations, GO-hybrid membranes exhibited excellent and stable sieving properties regarding molecules with hydrated radii larger than 0.487 nm by comparison to the original GO membrane. This investigation on the enhancement of laminated GO-hybrid membranes through organic cations complexation provided an alternative way to construct and customize stable GO-based membranes for separation process in the aqueous phase.