Instantaneous Free Radical Scavenging by CeO2 Nanoparticles Adjacent to the Fe−N4 Active Sites for Durable Fuel Cells

Abstract To achieve the Fe−N−C materials with both high activity and durability in proton exchange membrane fuel cells, the attack of free radicals on Fe−N 4 sites must be overcome. Herein, we report a strategy to effectively eliminate radicals at the source to mitigate the degradation by anchoring CeO 2 nanoparticles as radicals scavengers adjacent (Sca ad‐CeO2 ) to the Fe−N 4 sites. Radicals such as ⋅OH and HO 2 ⋅ that form at Fe−N 4 sites can be instantaneously eliminated by adjacent CeO 2 , which shortens the survival time of radicals and the regional space of their damage. As a result, the CeO 2 scavengers in Fe−NC/Sca ad‐CeO2 achieved ∼80 % elimination of the radicals generated at the Fe−N 4 sites. A fuel cell prepared with the Fe−NC/Sca ad‐CeO2 showed a smaller peak power density decay after 30,000 cycles determined with US DOE PGM‐relevant AST, increasing the decay of Fe−NC Phen from 69 % to 28 % decay.