Multifunctional Nafion/CeO₂ Dendritic Structures for Enhanced Durability and Performance of Polymer Electrolyte...

The development of a novel approach to achieve high-performance and durable fuel cells is imperative for the further commercialization of proton-exchange (or polymer electrolyte) membrane fuel cells (PEMFCs). In this work, multifunctional dendritic Nafion/CeO₂ structures were introduced onto the cathode side of the interface between a membrane and a catalyst layer through electrospray deposition. The dendritic structures enlarged the interfacial contact area between the membrane and the catalyst layer and formed microscale voids between the catalyst layer and gas diffusion medium. This improved the PEMFC performance through the effective utilization of the catalyst and enhanced mass transport of the reactant. Especially, under low-humidity conditions, the hygroscopic effect of CeO₂ nanoparticles also boosted the power density of PEMFCs. In addition to the beneficial effects on the efficiency of the PEMFC, the incorporation of CeO₂, widely known as a radical scavenger, effectively mitigated the free-radical attack on the outer surface of the membrane, where chemical degradation is initiated by radicals formed during PEMFC operation. These multifunctional effects of the dendritic Nafion/CeO₂ structures on PEMFC performance and durability were investigated using various in situ and ex situ measurement techniques.