ELECTRODE POTENTIAL REDISTRIBUTION DURING SILVER OXIDATION AND REDUCTION IN ALKALINE SOLUTION

摘要

Unexpected changes of measured cyclic voltammograms were observed upon applying automatic ohmic-drop compensation in the electro-oxidation of silver electrodes. A relatively strong shift was observed for the anodic peak which corresponds to AgO formation. No such shifts were measured for the oxidation process leading to Ag2O and for the sharp cathodic peak that corresponds to the reduction of Ag2O to Ag. With a new technique, which allows the in situ recording of the uncompensated resistance R(u), pronounced changes of its magnitude were observed during the cyclic sweep. Photocurrent and impedance spectra measurements during the cyclic voltammetry revealed that a significant potential drop appears in the semiconducting Ag2O, due to the formation of a depletion layer at the oxide/electrolyte interface. The importance of the redistribution of the electrode potential for the interpretation of cyclic voltammetry data is pointed out and discussed. [References: 35]