Molecular Dynamics Simulation of Scattering and Surface Diffusion of Oxygen Molecules on Ionomers in Catalyst Layers of PEFCs

Abstract

We analyzed the influence of the interaction between oxygen molecules and ionomer surfaces on the overall oxygen transport in the catalyst layer of polymer electrolyte fuel cells using a Monte Carlo (MC) method and the molecular dynamics (MD) method. We analyzed how gas–surface interaction parameters of oxygen molecules on the ionomer surface affects the overall transport by the MC method, and found that the conditions of surface diffusion affect much on the overall transport properties. We analyzed how oxygen molecules colliding with the ionomer surface behave using the MD method. When the results were compared, it was found that the ease of movement in the surface diffusion greatly affects the overall transport. We obtained the results of the residence time of the oxygen molecules on the ionomer surface. Moreover, it was suggested that further analysis on the behavior of oxygen molecules on the ionomer surface is necessary in order to more accurately calculate the overall oxygen transport in the catalyst layer.