Cyclic voltammetry and passivation behaviour of lead in Na2HPO4 solution

The electrochemical and passivation behaviour of lead electrode in 0.10 mol dm−3 Na2HPO4 solution was studied using cyclic voltammetric technique and complemented by X-ray surface analysis. The anodic half-cycle of the voltammogram exhibits active, pre-passive, passive and transpassive regions before the oxygen evolution. Passivity is due to the formation of thick porous PbO film by three-dimensional nucleation and growth on the electrode surface. The transpassive region is attributed to the electroformation of PbO2. The cathodic half-cycle shows two cathodic peaks as well as a small shoulder at the extreme negative potential just before the hydrogen evolution. The mechanism of formation of the passive film is discussed.