A channel flow electrode system has been applied to the studies of copper anodic dissolution mechanism in alkaline aqueous solutions (pH>10) containing chloride and carbonate ions. Anodic polarization curve of Cu indicates two pronounced Tafel regions followed by respective anodic peaks. It is found by the channel flow electrode method that Cu dissolves as Cu (I) ion and Cu (II) ion into the solution in the first Tafel region and the second Tafel region, respectively. The first Tafel region has the slope of 60mV/decade in the potential range of -0.5 to -0.2V vs. Ag/AgCl electrode. The current in this region depends upon the pH (∂ logi/∂ pH=1). On the other hand, the current in the second Tafel region, having a slope of 40mV/decade in the potential range of -0.2 to 0V, is independent of pH and the concentration of Cl-. The remarkable effect of carbonate ion appears on the current in the second Tafel region (∂logi/∂log[CO32-]=1). The anodic oxidation mechanisms of Cu in alkaline aqueous solutions containing carbonate and chloride ions have been proposed on the basis of the Tafel slopes and the reaction orders of proton, carbonate and chloride ions.
