Kinetics and Mechanisms of Cu Electrodissolution in Chloride Media

Ring‐disk electrode studies of anodic polarization of Cu in acidic chloride solutions indicate four distinct potential regions: the apparent Tafel region, the peak current and current minimum region, the limiting current region, and potentials above the limiting current region. Ring currents measured the flux of cuprous and cupric species from the disk. Dependence of disk and ring currents on H + and Cl − and on rotating rate has been determined. Models are proposed to describe Cu electrodissolution in the apparent Tafel region and the potential region above the limiting currents. The results indicate mixed mass‐transfer and kinetic control with cuprous chloride complex as the limiting diffusion species in the apparent Tafel region. At potentials above the limiting current region, there is simultaneous mass‐transfer control of the cuprous chloride complex and kinetic control of Cu ++ formation via the reaction, CuCl 2 − = Cu + + + 2 Cl − + e . Within the peak current and current minimum region and the limiting current region, Cu electrodissolution by mass transport is controlled in accord with previous work.