Abstract
The electrochemical reactions of a copper electrode in Na2S solution were studied using cyclic voltammetry, potentiostatic and galvanostatic measurements. In addition surface examination and morphological studies were applied using scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), and X-ray powder diffraction. Three anodic peaks were found in the anodic branch of the voltammograms. These peaks correspond successively to the formation of Roxbyite (Cu2-xS), Covellite (CuS) and possibly CuO. On the other hand, the cathodic branch contains four peaks. These peaks correspond mainly to the reduction of copper oxide and the copper sulfides formed on the anodic branch. The ternary compound NaCu5S3 is formed by a consecutive reaction of cuprous sulfide with sodium sulfide.