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 O-2, 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 kPa(abs)) 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. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.088205jes] All rights reserved.