A KINETIC-STUDY OF THE ELECTROFORMATION OF PBO2 ON PB ELECTRODES IN SULFURIC-ACID-SOLUTIONS

The electrochemical behaviour of Pb electrodes in 5 M H2SO4 was examin ed in the potential range of PbO2 stability using steady-state polariz ations and voltammetry combined with potentiostatic current transient techniques. The potentiostatic electroformation of PbO2 can be mainly interpreted as an instantaneous nucleation and two-dimensional growth mechanism under charge transfer control associated with the beta-PbO2 phase generation. From the parametric identification procedure of the whole set of potentiostatic current transients and the corresponding p otential dependence of the fit parameters, reasonable values of the ph ysicochemical constants included in the reaction model have been obtai ned. Reaction and system modelling also take into account the contribu tion of the oxygen evolution reaction (OER) kinetics on the top and ed ges of beta-PbO2 growth centres at high overpotentials. Copyright (C) 1996 Elsevier Science Ltd