The degradation mitigation effect of cerium oxide in polymer electrolyte membranes in extended fuel cell durability tests

In this work, two formulations of cerium oxide nanoparticles were incorporated into perfluorosulfonic acid membrane electrode assemblies (MEAs) and their ability to improve the in-situ membrane durability was studied by subjecting them to 94 and 500 h open-circuit voltage hold accelerated durability tests. In the shorter test the open circuit voltage decay rate was reduced by half and the fluoride emission by at least one order of magnitude, though no effect on hydrogen crossover or performance on the baseline MEAs was measured. The presence of the additive increased the particle size but decreased the number of platinum catalyst particles that were deposited in the membrane. The main Pt band was found at the predicted location; however, the incorporation of ceria caused a broadening with particles reaching further into the membrane. In 500 h tests, ceria-containing MEAs demonstrated a seven-fold decrease in open-circuit voltage decay and three orders of magnitude reduction in fluoride emission rates with unchanged performance and hydrogen crossover, remaining effectively pristine whilst the baseline MEA underwent catastrophic failure.