Oxidations at copper electrodes

The results of an investigation of polycrystalline copper electrodes in NaOH solutions by linear sweep voltammetry are presented. Two major reaction peaks were observed in sweeping from the potential for the hydrogen evolution reaction to that for the oxygen evolution reaction. These reaction peaks have been interpreted as the formation of Cu(I) and Cu(II) oxides at the electrode. The peak for the formation of Cu(II) is ten times larger in magnitude than that for the formation of Cu(I). At fast sweep rates the Cu(II) peak is resolvable into two components. These components apparently represent the formation of soluble and insoluble Cu(II) species. It is suggested that the transference of ionic species in the solid phase is the rate controlling process in the formation of Cu2O.