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.