Impedance Relaxation Spectrum Analysis of Oxidized Silver Electrodes

Abstract : The real and imaginary parts of the impedance of the oxidized silver electrode in 1M KOH solutions, have been measured in a frequency range of 1- 13,000,000 Hz. When the electrode is oxidized at a potential when only Ag2O is formed, we were able to isolate three passive elements: the high frequency capacitance and the high and low frequency resistances. On further oxidation, at a potential in which AgO can be formed, we were able to isolate five passive elements: two capacitance and three resistive. Two of these elements were identified as originating from the Ag2O layer. The functional dependence of all these elements on the amount of charge that is used for oxidation, reveals that the Ag2O layer can be analyzed in terms of a single dielectricum in a parallel plate capacitor. Parameters such as thickness of the layer, resistivity of the material and roughness factor could be evaluated. We have found that at the potential in which AgO is formed, significant fraction of the charge is being used for formation of Ag2O. (Author)