The electrochemical responses of Pb and Pb-3.4% Sb electrodes in 5 M H2SO4 were examined combining potential sweep and potential step techniques. The presence of antimony prevents the complete blockage of the electrode active surface by PbSO4 crystals during electro-oxidation, changing the composition and structure of the passive layer. The electro-oxidation of Sb was interpreted in terms of an adsorption-dissolution mechanism where in the rate-determining step one electron is transferred. The growth kinetics of the PbO inner layer was also studied. On the Pb-Sb electrode, the growth rate of PbO decreases because of a change in the transport mechanism of ions through the anodic layer.
lead-antimony; lead-antimony electro-oxidation; lead-antimony alloy electrochemical behavior
