Coupled Partial Ion‐Transfer Steps in the Anodic Dissolution of Metals

Abstract

A new model is proposed for the anodic dissolution of metals. It is assumed (i) that the rate‐determining process is the transfer of metal ions through the double layer, (ii) that ion‐transfer proceeds in two steps via an adsorbed, partially solvated ionic intermediate, and (iii) that the surface concentration of the intermediate species affects the potential distribution across the double layer, hence also the ionic transfer rate. It is shown that the model can explain the current‐potential characteristics and the electrical impedance of anodically dissolving metals. The low‐frequency loop of the electrical impedance is shown to arise from relaxation of the double layer during transfer of an ion. © 1999 The Electrochemical Society. All rights reserved.