Cyclic voltammetric studies of the electrochemical behaviour of copper-silver alloys in NaOH solution

Cyclic voltammetric curves of two (Cu-20% Ag and Cu-80% Ag) binary alloys were recorded in NaOH solutions at 25 degreesC. The resulted voltammograms of the alloys are complex and consist of the superposition of the cyclic voltammograms of pure Cu and Ag. Below certain critical anodic potentials, Cu dissolves preferentially and the voltammograms exhibit three anodic and cathodic peaks corresponding to the formation and reduction of Cu2O, Cu(OH)(2) and CuO. Beyond a critical potential, Ag dissolves and the voltammograms show three further anodic and cathodic peaks corresponding to the formation and reduction of AgO. Ag2O and AgO. Grazing-angle X-ray diffraction of the surface products at different anodic potentials confirmed results. The heights and locations of the peaks depend on the composition of the alloy. the concentration of the alkali, and the sweep rate. (C) 2002 Published by Elsevier Science B.V.