The time-resolved EQCM and study of the kinetics of silver(I) oxide formation on a polycrystalline silver electrode in alkaline solution

Abstract The time-resolved EQCM method is described and a theoretical analysis of the relation between the frequency resolution and the sampling rate (time resolution) is presented. It is shown that the time-resolved EQCM can fulfil simultaneously good frequency resolution and time resolution. The kinetics of the oxidation of Ag to Ag 2 O are studied using this method combined with the potentiostatic technique. The monolayer Ag 2 O formed at the first stage shows a potential dependent coverage. In the first two stages, the Ag 2 O layer thickens layer by layer with a rate-determining step of diffusion of Ag + to the surface, where it forms an Ag 2 O base layer. The frequency transients associated with the formation of the bulk phase Ag 2 O are well consistent with the current transients, and both indicate an instantaneous nucleation and 3D growth mechanism. A relatively accurate method to estimate the mean height h of the cavities at the rough surface is also presented based on the frequency transient and charge density, and a linear increase of h with anodic charge is observed during the potentiostatic process. It has been demonstrated that the time-resolved EQCM can provide valuable information on the transient change of the morphology at the electrode|electrolyte interface.