A computer simulation of voltammograms describing the active-passive transition of Pb in sulphuric acid

Abstract

A computer simulation of active-passive transition voltammograms of Pb in 5M H₂SO₄ is presented The model unphes alternatlve pathways leading to the formatron of Inner and outer structurally different PbSO₄ layers The inner layer consists of a dtsordered crystallme conductmg phase, which 1s formed followmg an instantaneous nucleation and twodlmenslonal growth mechanism under chargetransfer control Electrodlssolutlon of Pb proceeds by the dlffuslon of cations through the inner layer and, when Pb²⁺ ion concentration in solution exceeds the cntical supersaturation concentration, the precqutatlon of the outer highly crystalline PbSO₄ layer takes place, leading to passlvatlon Calculations are based on premously reported kinetic data. Good agreement was found between theory and practice.