Effects of Pt particle on structure and protons transport of Nafion membrane

With proton exchange membrane fuel cell (PEMFC) running, Pt particles are re-deposited in proton exchange membrane PEM after the degradation and migration of Pt cathode catalyst. Classic molecular dynamics simulations are conducted to study the effects of Pt particle on the structure and protons transport of Nafion membrane. The structure of membrane around a Pt particle is observed to present a core–shell structure. The Pt particle is the core coated by the shell of Nafion polymers, with the side-chains of polymers wrapping snugly around the particle. In that structure, some hydronium ions locate in inner shell owing to the electrostatic action with sulfonic acid groups, and few water molecules near particle due to few voids in the structure and hydrophobicity of the backbone of polymers. Besides, the diffusion for hydronium ions irregularly changes over the number of Pt atoms thanks to irregular changes of water channels. While the hopping of protons is to decline over Pt atoms due to greater loss of hydrogen bonding acceptable sites caused by larger particle.