Effect of Electrolyte on the Proton Transport through Graphane in the Electrochemical Cell: A First-Principles Study

The proton transport behaviors through graphane in the electrochemical environment are not only determined by the film but also correlated with the properties of the electrolytes. Here, the effect of electrolytes is studied for this transport process. The step of proton transfer from electrolyte to graphane is the rate-determining step of the whole transport process in most of the studied cases and is indeed influenced much by the electrolytes, while the following steps are affected little. Its energy barrier increases significantly with the number of water molecules but only fluctuates with the number of mimicked Nafion molecules until the bulk case. This barrier could be further affected by the hydration number of Nafion and be reduced by increasing local proton concentrations. The dynamical effect of the environment and the nuclear quantum effect are found to further reduce the energy barrier of the transport process but by a relatively small amount.