Use of transient techniques in the study of electrocrystallisation in the reduction of Cu + ions in fused LiCl+KCl

Abstract

Transient electrochemical methods are applied in the study of the early stages of copper deposition on inert electrodes of vitreous carbon or graphite from a solution of Cu + in fused LiCl−KCl. The rising current transient resulting from the three-dimensional electrochemical nucleation is related to the number density of surface nuclei in terms of diffusion of metal ions towards isolated growing hemispheres. In this approach the diffusion coefficient of Cu + ions deduced from other independent measurements (capillary technique with radioactive tracers) is used. The kinetics of nucleation of the metal deposit are described for potentiostatic and galvanostatic conditions. The overvoltage required for the growth of stable nuclei is examined as a function of nucleus size and of interfacial energy. It is shown that the surface properties of the electrode material may have a catalytic effect on the nucleus creation.