Copper electrodissolution in 1 M HCl at low current densities. II. Electrochemical impedance spectroscopy study

Anodic oxidation of a copper rotating disk in 1 M HCl is studied by electrochemical impedance spectroscopy (EIS). Experimental impedance diagrams show two capacitive loops separated in frequency. These diagrams validated with Kramers-Kronig relationships reveal a change in the frequency f(c), at the apex of the low frequency loop, with the electrode potential. The theoretical expression for the impedance is derived and the possible limiting shapes of the impedance diagrams are discussed. The low frequency loop can take different forms as a convective-diffusion loop, a first order semi-circle or a mixed graph. An increase in f(c) with the electrode potential should be observed. Fitting of the impedance diagrams by the kinetic model gives good agreement with the experimental frequency distribution. A discussion is presented between the theoretical and experimental results. (C) 1998 Elsevier Science Ltd. All rights reserved.