Electrochemistry of Lead, Antimony, and Lead-Antimony Alloys in Sulfuric AcidSolutions

摘要

The effect of Sb on the electrochemical behavior of Pb in H2SO4 solutions isclarified using two different approaches. First, Sb is found to increase the rate constant for the parabolic growth of oxide on Pb in the PbO2 potential region. This indicates that the presence of Sb increases the diffusion rate of oxygen species in the Pb oxide layer. Second, the electrochemical behavior of pure Pb, pure Sb, and Pb-Sb eutectic is investigated from a mechanistic point of view. The release of soluble Pb(IV) species into H2SO4 during the polarization of Pb is proved, and their role is discussed. A mechanism for the dissolution of Sb is suggested. Only trivalent soluble and solid oxidation products of Sb are detected, even at potentials well above the equilibrium potential of the Sb(V)/Sb(III) couple. Sb is found to affect the electrochemical behavior of Pb both via the formation of a doped Pb oxide or a mixed Pb-Sb oxide, which improves the conductivity of the anodic layer, and via the adsorption of Sb species on the oxidation products of Pb.