Local Impact of Pt Nanodeposits on Ionomer Decomposition in Polymer Electrolyte Membranes

Based on recent theoretical studies, we designed a multistep experimental protocol to understand the impact of environmental conditions around Pt nanodeposits on membrane chemical degradation. The first experiment probes the local potential at a Pt microelectrode for different rates of permeation of hydrogen and oxygen gases from anode and cathode side. The subsequent degradation experiment utilizes the local conditions taken from the first experiment to analyze local rates of ionomer degradation. The rate of ionomer decomposition is significantly enhanced in the anodic H2-rich membrane region, which can be explained with the markedly increased amount of H2O2 formation at Pt nanodeposits in this region.