Voltammetric Characterization for the Growth of Oxide Films Formed on Copper in Air

Abstract

The growth mechanisms of oxide films thermally formed on copper have been studied using “double sweep cyclic voltammetry” in strongly alkaline electrolytes. It was found that an electrolyte of 6M KOH+1M LiOH allowed perfect resolution of catholic waves due to the reduction of Cu₂O and CuO. The effect of the types of anion on copper oxidation mechanism was investigated in many factors of corrosion. Copper sheets were prepared by pre-immersion in various electrolytes of sodium salt, followed by heating in air at 80°C and 90% RH. The formation kinetics of each oxide films followed the parabolic rate law with a few exceptions. These were confirmed that the formation of the oxide films was accelerated with the increase of ions on copper and that the oxidation rate of Cu₂O or CuO was controlled by the types of anion.