A Model Study for Oxygen Reduction Reaction and Durability of Pt/C Catalyst in Triple-Phase Boundary of PEFCs

Abstract

We developed a novel solid-state electrochemical cell for modeling triple-phase boundary of polymer electrolyte fuel cells and investigated oxygen reduction reaction (ORR) activity and durability of Pt/C catalysts using the cell. ORR current was depended on relative humidity as well as the thickness of coated Nafion layer on the model electrode. We also conducted the theoretical calculation and clarified that ORR current in the model TPB region is not restricted by oxygen diffusion but by an ohmic drop due to proton migration in the coated Nafion layer on the model electrode. Durability test of Pt/C catalysts in the model TPB region was carried out under oxygen atmosphere. After the test, aggregation and somewhat larger Pt particles were observed on the model electrode at which electrode potential would reach to be open circuit potential, i.e., low overpotential region, under oxygen atmosphere.