ChemInform Abstract: The Electrochemical Oxidation of Silver in Chromate Solutions

ChemInform Abstract

and the subsequent reduction of the Ag₂CrO₄ formed are investigated by using linear potential sweep voltammetry as the main technique. In a solution containing only perchlorate Ag dissolution and deposition are observed exclusively. When the electrolyte contains 1·10^-3 M chromate a small shoulder in the voltammogram points at additional Ag₂CrO₄ formation. At higher concentration of chromate this peak is fully resolved. The Ag₂CrO₄ grows as a film and does not impede the Ag dissolution when formed at < 10^-2 M. In more concentrated chromate solution the Ag surface is passivated by a layer of Ag₂CrO₄ and the dissolution process is suppressed. At chromate concentration of 1 M, anodic oxidation of the Ag electrode yields a duplex layer of Ag₂CrO₄ consisting of a compact layer, formed below about 0.4 V (SSCE), and a powdery film, which forms above this potential on the surface of the compact layer.