Hard anodization of copper in potassium carbonate aqueous solution

Abstract Anodization of copper was performed in potassium carbonate aqueous solution. Registered current curves allowed to claim that the anodic oxide film growth occurs according to the hard anodization mechanism. Detailed investigation of the anodization products revealed formation of nanowires made of crystalline phases including various oxides and complex phases containing hydroxyl anions and carbonates. It was found that the diameter of the nanowires grows linearly with the anodizing voltage between 30 (10 V) and 47 nm (50 V). The major, crystalline components of the anodically grown nanowires were: paramelaconite (Cu4O3), cuprite (Cu2O) and tenorite (CuO). The presence of malachite, Cu2CO3(OH)2 was also reported and meant effective incorporation of the electrolyte anions into the growing anodic film.