Electrochemical performance of a Pb/Pb-MnO2 composite anode in sulfuric acid solution containing Mn2+

The influence of Mn2+ on oxygen evolution kinetics and corrosion behaviour of Pb/Pb-MnO2 composite anode in sulfuric acid electrolyte was investigated using SEM, XRD, and several electrochemical methods. The results indicate that a high concentration of Mn2+ (e.g. 3.0 gL(-1)) in the electrolyte resulted in the formation of a MnO2 layer on the surface of the anode. This layer decreased the oxygen evolution activity of the anode, but at the same time made the underlying PbO2 layer more compact and flat, effectively improving the anodic corrosion resistance. When the Mn2+ concentration was low (e.g. 0.1 g L-1), no MnO2 layer was formed but the structure of the PbO2 anodic layer was modified. As a result, the oxygen evolution activity and corrosion resistance were both significantly improved. In addition, Mn2+ in the electrolyte did not change the kinetic mechanism of oxygen evolution reaction. The reaction was exclusively controlled by the formation and adsorption of first intermediate, and the adsorption resistance played a dominant part in the whole reaction resistance. (C) 2011 Elsevier B.V. All rights reserved.