Electrochemical behavior of copper electrode in sodium hydroxide solutions

Abstract

The cyclic voltammograms of the copper electrode in different concentrations of NaOH solutions was studied using cyclic voltammogram's (CV's) technique. In addition surface examination and morphological studies were also conducted using scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDAX). The four anodic peaks where founds to correspond successively to the formation of a mono layer of Cu 2 O, a thick layer of CuO and CuO 2 2- and finally the formation of a higher oxide Cu2O3 before the evolution of oxygen. It is suggested that the CuO is formed from the oxidation of Cu 2 O and/or direct oxidation of metallic copper in 5M NaOH solution. The ratio of anodic and cathodic charge was found to be about unity, indicating the quantitative reduction of solid oxidation product. The behavior of copper electrode in NaOH solutions was found to be quite complicated. Thus, no simple relation were found between the voltage scan rate and both the peak current and peak potential or between the peak K current and alkali concentration of alkali.