Potential dependent growth of Cu(OH)2 nanostructures on Cu and their thermal conversion to mixed-valent copper oxides p-type photoelectrode

Abstract

Abstract Herein, we report the anodic growth of nanostructured Cu(OH)2 thin films on the copper surface by potentiostatic and potentiodynamic methods. The phase formation, crystalline feature, morphology and the progressive growth of Cu(OH)2 thin films were controlled by the applied potential and concentrations of alkali utilized in anodization process. Electrochemical investigations suggest the rapid growth of Cu(OH)2 and passivation at higher anodization potentials. In contrast, the lower anodization potentials favours the progressive growth of Cu(OH)2 nanorod like features. The thermal treatment of Cu/Cu(OH)2 reveals the formation of crystalline mixed copper oxide film with predominantly Cu2O phase at 673\xa0K and 773\xa0K. Photoelectrochemical investigations of these copper oxide thin films exhibit the p-type behavior with repeatable photovoltage (55\xa0mV) and stable photocurrent responses (20–60\xa0μA\xa0cm−2). The hydrogen evolution studies show better activity with nanostructured Cu(OH)2 and copper oxides than with aggregated thin films and bare substrate.