Impedance of a Disk Electrode with Reactions Involving an Adsorbed Intermediate: Experimental and Simulation Analysis

A comparison of experimental results with numerical simulations is presented that shows the influence of electrode geometry on the impedance response for reactions involving one adsorbed intermediate. The local electrochemical impedance measurements performed on an iron disk electrode were in qualitative agreement with the numerical calculations. Both the experimental and calculated local impedances exhibit a time-constant dispersion induced by the nonuniform current and potential distributions on a disk electrode. The geometry effects were reflected in the complex local ohmic impedance behavior at low frequencies as well as at high frequencies. It was shown that the low frequency imaginary contribution to the ohmic impedance became more significant at a more anodic potential. © 2009 The Electrochemical Society. DOI: 10.1149/1.3123193 All rights reserved.