Ceria nanorods as highly stable free radical scavengers for highly durable proton exchange membranes.

Chemically durable proton exchange membranes containing free radical scavengers have technically matured in recent years, and commercial products have come into the market. The most general type of free radical scavenger is ceria, which has been proven in many studies. However, the migration of cerium is inevitable in raw ceria particles, and the migrated cerium species can aggregate in catalyst layers, causing performance loss of fuel cells. In this work, the morphology of ceria was changed from conventional nanoparticles to nanorods, and the migration of cerium was mitigated significantly. Both ex situ Fenton's degradation tests and in situ fuel cell accelerated degradation tests (ADTs) indicated that ceria nanorods have free radical scavenging properties comparable to those of ceria nanoparticles. Moreover, the immobilization of ceria particles and antidissolving properties have been verified by Fenton's degradation tests, electric field tests and fuel cell ADTs.