A Promising Anhydrous Proton Transport Membrane: Hydroxyl Functionalized Graphane

Hydrogen fuel cells have high potential for becoming a major alternative to traditional combustion engines. An important component to these fuel cells include surfaces made of proton conducting material which allow the transfer of H⁺ ions from anode to cathode at relatively high rates. Commercial proton transport membranes, such as Nafion, experience limited operation temperature due to the need for hydration. Graphane membranes functionalized with hydroxyl groups conduct protons at significant rates without a hydrated surface. Density functional theory calculations show that a 1-dimensional hydroxyl chain on graphane has a proton diffusion coefficient that is an order of magnitude higher than that of Nafion. We have investigated the transport properties of a membrane functionalized with a 2-dimensional network of hydroxyl chains that we proposed to be more prominent and capable of operating at higher temperatures than commercial membranes. We have performed molecular dynamics simulations on model surfaces using the Vienna Ab-initio Simulation Package (VASP). Our simulations occurred within a range of high temperatures (300K-1000K). Diffusion coefficients were obtained at each temperature, and the activation energy for proton transport on our membrane was determined.