Abstract
We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level using classical molecular dynamics simulations. The new empirical valence bond (EVB) model is developed based on the previous study of EVB model reported by Walbran et al. in order to improve the description of proton mobility in both aqueous and Nafion environments. In addition to determination of diffusion coefficients of hydronium ions and water molecules as a function of hydration level as a dynamical analysis calculated by mean square displacement, we have also calculated radial distribution functions of hydronium ions and water molecules around the first solvation shell of sulfonate groups for structural analysis. A large contribution of Grotthuss mechanism for the diffusion of hydronium ions has been found at λ= 6 and this implies the important impact of Grotthuss mechanism in the membrane as well as in the bulk aqueous solutions.
