APPLICATION OF TIME-RESOLVED EQCM TO THE STUDY OF THE MECHANISM OF SILVER(I) OXIDE FORMATION ON A POLYCRYSTALLINE SILVER ELECTRODE IN ALKALINE-SOLUTION

The time-resolved EQCM was used to investigate the mechanism of the el ectrochemical formation of silver(I) oxide on a polycrystalline silver electrode in 0.1 M NaOH. The mass change was monitored in a series of potentiodynamic experiments. The first stage of the oxidation can be unambiguously attributed to the formation of a monolayer of Ag2O. In t he second stage of the oxidation, a very small amount of Ag or its oxi de dissolves into the solution and the Ag2O layer thickens gradually. No species other than Ag2O was detected during the whole oxidation pro cess. The structure of the Ag2O layers formed is different at differen t stages of the oxidation. Compact Ag2O layers are formed in the first two stages, while Ag2O formed at more positive potentials is porous. The roughening of the electrode during the formation and reduction of the oxide is also discussed on the basis of the mass changes.