Membrane Degradation Mechanisms In Pemfcs

Based on experimental findings it is suggested that formation of active oxygen species from H2O2 decomposition or the direct formation of active oxygen species in the oxygen reduction reaction are not the dominating membrane degradation mechanisms in PEMFCs, instead it is the molecular H2 and O2 that react on the surface of the Pt catalyst to form the membrane degrading species. The source of H2or O2 is from reactant crossover through the membrane. The reaction mechanism is chemical in nature and depends upon the catalyst surface properties and the relative concentrations of H2 and O2 at the catalyst. The membrane degradation rate also depends on the residence time of the species in the membrane and the volume of the membrane. The sulfonic acid groups in the Nation® side chain are key to the mechanism by which the radical species attack the polymer. copyright The Electrochemical Society