Perfluoroalkylic decorated cerium oxide nanoparticles as compatible radical scavengers in Aquivion®-based proton exchange membrane fuel cells with improved durability

Proton exchange membrane fuel cells (PEMFCs) are highly efficient devices for converting chemical energy into electrical energy. At present, however, their large-scale implementation is primarily hindered by the limited lifetime of the membrane electrode assembly (MEA), which typically utilizes perfluorinated ionomers, such as Nafion™. Current research focuses on incorporating radical scavenging species into the MEA to enhance durability. This work investigates the use of functionalized CeO2 nanoparticles coupled with Aquivion®, a short-side-chain ionomer that outperforms state-of-the-art Nafion™. The novelty lies in the application of organosilanes bearing fluorinated chains as grafting agents on the CeO2 surface to improve filler-polymer compatibility. The most promising nanocomposites exhibit uniform filler dispersion, and a 50% reduction in both swelling ratio and ex-situ fluoride ions emission rate, while maintaining conductivity values above 150 mS cm−1 at 80 °C and 100% RH. Furthermore, fuel cell performance comparable to, or exceeding, pristine Aquivion® was observed, with negligible degradation after >650 h of accelerated stress testing. These findings could pave the way for a new generation of composite membranes featuring polymer-tailored scavenger functionalization.