ELECTRODE POTENTIAL REDISTRIBUTION DURING SILVER OXIDATION AND REDUCTION IN ALKALINE-SOLUTION

Unexpected changes of measured cyclic voltammograms were observed upon applying automatic ohmic-drop compensation in the electro-oxidation o f silver electrodes. A relatively strong shift was observed for the an odic peak which corresponds to AgO formation. No such shifts were meas ured for the oxidation process leading to Ag2O and for the sharp catho dic peak that corresponds to the reduction of Ag2O to Ag. With a new t echnique, which allows the in situ recording of the uncompensated resi stance R(u), pronounced changes of its magnitude were observed during the cyclic sweep. Photocurrent and impedance spectra measurements duri ng the cyclic voltammetry revealed that a significant potential drop a ppears in the semiconducting Ag2O, due to the formation of a depletion layer at the oxide/electrolyte interface. The importance of the redis tribution of the electrode potential for the interpretation of cyclic voltammetry data is pointed out and discussed.