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

• Published in: Denki kagaku oyobi kōgyō butsuri kagaku 2013/07/05, Vol.81(7), pp.547-552
• Main Authors: KANZAKI, Yasushi, BRUCKENSTEIN, Stanley
• Format: Article
• Language: English
• Subjects: Anodic Dissolution; Byproducts; Copper; Electrodes; Mixed Potential; Oxygen; Oxygenated; Rotating; Sulfuric acid; Thermodynamic equilibrium
• ISSN: 1344-3542; 2186-2451
• DOI: 10.5796/electrochemistry.81.547

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.