PHYSICOCHEMICAL PROPERTIES OF ELECTRODEPOSITED BETA-LEAD DIOXIDE - EFFECT OF DEPOSITION CURRENT-DENSITY

The influence of current density on the coulometric efficiency of beta-PbO2 deposition in 0.5 M lead nitrate, the nonstoichiometry, impurity of alpha-PbO2 and voltammetric double layer capacitance have been studied. While the coulometric efficiency is about 95% at current densities less than 30 mA cm-2, it decreases at higher current densities. The oxygen deficiency, delta, in beta-PbO2-delta has been found to be invariant with the current density. X-ray diffraction studies provide a linear decrease in the weight percent of alpha-PbO2 as an impurity in the beta-PbO2 with increase in current density, and the alpha-PbO2 is found to be absent at 100 mA cm-2 or higher. The estimated double layer capacitance from the cyclic voltammograms recorded in the potential range 0.70-1.10 V, increases with deposition current density, indicating enhanced surface area.