The kinetics of the reduction processes of PbO film in H 2SO 4: Part 5. Potential step method on Pb + Sb alloy electrodes

Abstract

The kinetics of the processes of reducing tetragonal PbO to Pb on Pb + Sb alloy electrodes has been studied by the potential step technique. Experimental results indicate that the process is limited by solid state nucleation and growth. Antimony can accelerate the initial instantaneous nucleation and growth of metallic lead, so that the process is mainly controlled by ion diffusion on the high antimony alloy electrodes. In the potential step from 600 to −750 mV (vs. Hg/Hg 2SO 4), the reduction of tetragonal PbO on Pb + Sb electrodes with antimony contents lower than 1.9% exhibits a two-dimensional instantaneous nucleation mechanism. The nucleation and growth rate perpendicular to the metal surface become more rapid with the decrease of antimony content and the increase of the reduction overpotential.