The kinetics of oxygen reduction reaction (ORR) on electrodes prepared with Nafion(superscript ®) and Pt/C were investigated by the rotating disk electrode (RDE) and cyclic voltammetry (CV) techniques. It indicated that the electrochemical active surface decreased with the increasing Nafion(superscript ®)/Pt ratio. From the Tafel plots (uncorrected for diffusion), the reaction rate of ORR increased as Pt-loading increased. However, from the corrected Tafel plots, the mechanisms of ORR were found to be chemical reaction control and mixed kinetic-diffusion control at low and high overpotential, respectively. The hydrodynamic voltammograms were analyzed to determine the kinetic parameters by using the modified Koutecky-Levich equation. The exchange current density for the Pt/C catalyst was determined to be 6.07×10^(-3) mAcm^(-2) based on the real Pt surface area. The results of this study may contribute to the design of the fuel cell electrodes using a Pt/C catalyst.
