KINETICS OF OXIDATION PROCESSES ON LEAD ELECTRODE IN H2SO4 .2. THE GROWTH OF THE PBSO4 AND PBO LAYER

The growth kinetics of both PbSO4 and PbO layers has been studied further. The growth rate of the PbSO4 layer depends on the migration of the SO42- ion through the micropores while that of the PbO layer depends on the migration of the Pb2+ and OH ion in the PbO layer and the H+ ion in the PbSO4 layer. The PbSO4 and PhO layers grow at the PbO . PbSO4/PbSO4 and metal/PbO interfaces, respectively. In the PbSO4 layer the concentrations of the SO42- and H+ ions decrease linearly with the distance from the PbSO4/bulk solution interface and the largest potential drop appears at the PbO . PbSO4/PbSO4 interface. Yet the concentrations of the Pb2+ and OH- ions remain unchanged and the diffusion potential drops linearly in the PbO layer.