Rotating ring-disk electrode study on the cathodic oxygen reduction at Nafion®-coated gold electrodes

The influence of Nafion(R) films on the kinetics of cathodic oxygen reduction was investigated using Nafion(R)-coated gold electrodes. A rotating ring-disk electrode (RRDE) technique was used to determine kinetic parameters for O-2 reduction and to detect intermediate H2O2 formation. Kinetic parameters such as the kinetic current, Tafel slope, potential dependence of the ratio of the direct 4-electron reduction to the series a-electron reduction were determined and compared with those obtained at bare Au in 0.5 M H2SO4. The kinetic data showed no clear evidence of the enhancement effects of Nafion(R)-coating on the cathodic O-2 reduction at Au. This suggested that the Au surface has less affinity for the hydrophobic region of Nafion(R), in which a high O-2 solubility is expected. (C) 1998 Elsevier Science S.A. All rights reserved.