Degradation mitigation in polymer electrolyte membranes using cerium oxide as a regenerative free-radical scavenger

The efficacy of CeO2 nanoparticles in mitigating free-radical-induced polymer electrolyte membrane (PEM) degradation is investigated. Commercially obtained CeO2 and nanoparticles synthesized in-house were incorporated within a recast Nafion membrane. Membrane electrode assemblies were prepared using Nafion and Nafion- CeO2 composite membranes (0.5, 1, and 3 wt % CeO2). The composite membranes exhibited very similar proton conductivities (∼35 mS / cm) and hydrogen crossover (∼1 mA / cm2) as Nafion. However, the fluoride emission rate (from accelerated tests) was lowered by more than 1 order of magnitude upon addition of CeO2 into the Nafion membrane, suggesting that CeO2 nanoparticles have tremendous potential to greatly enhance membrane durability.