Surface Corrugation Effects on the Water-Graphene Interfacial and Confinement Behavior

We carried out a systematic molecular simulation study of the behavior of a pair of finite-size graphene plates immersed in water at isobaric-isothermal conditions to provide insights into the nature of the water-graphene (corrugated) surface interactions. The goal was to address the link between the corrugation-driven hydration free energy changes in the association process involving graphene plates and the resulting water-graphene interfacial tension, to interrogate the effect of the surface corrugation and confinement on the thermodynamic response functions and the dynamics of confined water and to put the observed behavior in the context of Wenzel's modification of Young's equation. We found that graphene confinement induces a significant increase in the isothermal compressibility and isobaric thermal expansivity as well as a pronounced slowdown of the dynamics of water over that of the corresponding bulk counterpart, whose magnitudes depend on the type of surface corrugation involved. Our simulation results for different types of corrugated graphene plates involving identical surface areas do not support the meaning of the r-factor underlying Wenzel's equation for corrugated nanoscale surfaces.