Anodic oxidation of copper in alkaline solutions 2—the open-circuit potential behavior of electrochemically formed cupric hydroxide films

Abstract

Copper electrodes covered with Cu(OH) 2 films grown in 1 mol dm −3 LiOH solution have been examined using X-ray diffractometry, scanning electron microscopy and electrochemical techniques. A sharp change in potential on open-circuit, due to a change in phase from Cu(OH) 2 to Cu 2O, was observed. This phase change is accompanied by a substantial amount of film dissolution. The time required for transformation, and the final amount of Cu 2O formed, are functions of both hydroxide ion concentration and electrode rotation speed. A mechanism involving Cu(OH) 2 dissolution, disproportionation (Cu 2++Cu→2Cu +) and Cu 2O precipitation, is proposed to explain these observations.