POTENTIODYNAMIC BEHAVIOR OF BETA-LEAD DIOXIDE IN NEUTRAL MEDIA AT POSITIVE POTENTIALS

The behaviour of the PbO2 electrode in NaNO3, Na2SO4, NaClO4 and NaCl in the pH range 3.0-10.5 has been studied by cyclic voltammetry. When the electrode is cycled between 0.30 and 1.90 V, a large cathodic current peak appears in the negative scan; in the subsequent cycle, two anodic peaks appear. The addition of H2O2 at low concentrations to the electrolyte also results in two anodic peaks at the same potentials. A number of possible explanations for the appearance of the cathodic peak, and a mechanism for the oxidation of PbO to PbO2 through Pb3O4 corresponding to the two anodic peaks, are proposed.