AC ADMITTANCE STUDY OF THE PLATINUM-SULFURIC ACID INTERFACE

Apparatus for the measurement of the a-c admittance of electrodes using sweep-frequency techniques is described. Measurements of the Pt/1.0N H2SO4 interface are reported for the hydrogen adsorption, double-layer, and oxide regions. Rotating disk electrodes were used, and necessary corrections for nonuniform current distributions are discussed. A single relaxation time closely characterizes the hydrogen adsorption process at all potentials. No evidence for Faradaic processes was evident in either the double-layer or oxide regions, but the double layer capacitance exhibits a dispersion resembling that of a diffusional process. © 1979, The Electrochemical Society, Inc. All rights reserved.