Proton transport at interfaces and surfaces is of tremendous importance in diverse areas such as proton exchange membranes in fuel cells, biological membranes and proton pump channels. We are specifically interested in the transport of protons at interfaces for a better design of new materials for proton exchange membrane (PEM) fuel cells. The practical engineering motivation for developing new materials is to conduct protons for improved performance and reduce costs of hydrogen fuel cells.
We focus specifically on functionalized graphene for studying surface transport of protons in anhydrous conditions using density functional theory. The hypothesis is that a facile anhydrous proton transport will occur on a surface that has a continuous network of hydrogen bonded OH groups showing "grotthuss-like" mechanism. A simple 1-D hydrogen bonded network of hydroxyl groups on graphane membrane with one and two excess proton concentrations are studied. In this work, we have computed activation energy barriers and investigated mechanisms for proton transport reactions on the surface of functionalized graphene with varying excess proton concentrations. Ab initio molecular dynamics (AIMD) simulations with various density functional approximations are used to determine equilibrum and dynamical properties of fully hydroxylated graphene surface with one excess proton concentration will be discussed. We have developed a simple lattice model for the 1-D hydrogen bonded network to explore the cross-over from normal to single-file diffusion. We have developed a simple lattice model for the 1-D hydrogen bonded network to explore the cross-over from normal to single-file diffusion.