Pt-Oxide Coverage-Dependent Oxygen Reduction Reaction (ORR) Kinetics

Oxygen Reduction Reaction (ORR) currents have been measured under the potential range of an operating fuel cell (0.72–0.9 Volts) while keeping proton and oxygen transport-related overpotentials insignificant by testing with pure O2, at 100%RH and at low current densities. Low potential points are achieved by reducing the platinum loading on the cathode and operating under sub-ambient (<101.3 kPaabs) pressure. The resulting experimental data are fit to Pt-oxide-coverage-dependent kinetics and the kinetic parameters extracted. The impact of Pt-oxide on apparent Tafel-slope transition (i.e., a function of potential) and on ORR performance is discussed.