Thermal reduction to control the spacing in graphene oxide membranes: effect on ion diffusion and electrical conduction

Means to control the inter-layer spacing in graphene oxide and reduced graphene oxide membranes is required to tailor their properties. We report that based on the temperature of thermal reduction the interlayer spacing in these membranes can be controlled from 7.6 angstrom to 4.6 angstrom. This is the critical range that matches with the hydrated ionic radii of commonly found ions in water and hence is useful to tailor the diffusion characteristics of these membranes. In accordance with the change in inter-layer spacing, both the in-plane and out-of-plane electrical conductivity of the membranes also increases and this is also observed in the electrochemical characteristics of the membranes.