Electrochemical behaviour of a silver electrode in NaOH solutions

Studies of the electrochemistry of metals and alloys are very important fie lds of scientific and industrial work. The present investigation includes d etailed studies on the corrosion and electrochemical behaviour of Ag in aqu eous NaOH solutions under various conditions using cyclic voltammetry, chro noamperometry, and potentiostatic techniques. It was found that the anodic polarization curve of Ag in NaOH solutions is characterized by the occurren ce of five anodic peaks (A1-A5). A1 is due to the electroformation of solub le [Ag(OH)(2)](-) complex species, A2 to the electroformation of Ag2O, A3 t o nucleation and three dimensional growth of the Ag2O layer, A4 to the form ation of AgO, and A5 presumably to the formation of Ag2O3 X-ray diffraction patterns confirmed the existence of passive Ag2O and AgO layers on the ele ctrode surface potentiodynamically polarized up to oxygen evolution. The cathodic part of the cyclic voltammograms is characterized by the occur rence of an activated anodic peak (A6) corresponding to the electrooxidatio n of Ag to Ag2O and three cathodic peaks (C1, C2, C2') corresponding to the electroreduction of AgO to Ag2O and Ag2O to Ag, respectively.