Anodic Dissolution of Copper in Oxygenated Sulfuric Acid Solution as Examined by Rotating Ring-Disk Electrode

The anodic dissolution of copper was examined in oxygenated sulfuric acid solution. A characteristic property of the anodic process is that the oxidation process Cu → Cu2+ involves the detectable intermediate Cu+, which should disproportionate into Cu and Cu2+ in the thermodynamic equilibrium state. On the other hand, H2O2 was formed during anodic dissolution in oxygenated solution by the reaction of Cu+ with O2. The intermediate Cu+ and the byproduct H2O2 were detected in this study using a rotating ring-disk electrode. The anodic dissolution process including the role of oxygen was elucidated through the detection of Cu+ and H2O2. The decrease in the activity of Cu+ in the presence of O2 involved a negative shift of the partial current of Cu → Cu2+ (or Cu+), and resulted in a negative shift of the corrosion potential with increasing stirring rate of the solution. In addition, Cu+ was found to be not a transient intermediate, but rather, a thermodynamic equilibrium species. The acceleration of the corrosion rate in the presence of O2 was elucidated successfully to be due to the couple of the partial currents for Cu → Cu+ and O2 → H2O2.