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 H ₂O₂. 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 O ₂ → H₂O₂.