Electrochemical Properties of PbO[sub 2] and the Anodic Corrosion of Lead and Lead Alloys

The total amount of anodic corrosion of Pb and Pb‐Sb alloys in sulfuric acid under conditions of O 2 evolution can be evaluated by measuring the length of the potential plateau (transition time) during the electrochemical reduction of the layers, with a constant current, taking into account self ‐discharge and degree of utilization of the . Using high resolution techniques, a characteristic step in the potential plateau during discharge of the layer was discovered. This step can be attributed to a difference in discharge over‐voltage between . For alloys of the Pb‐Sb system, constant current corrosion increases slightly with increasing Sb concentration, whereas oxygen overvoltage decreases and constant potential corrosion strongly increases with increasing Sb concentration. Precise electrode potential measurements of the and the couple gave and , respectively, vs. H 2 in 4.40M sulfuric acid at 31.8°C. These two oxides have different oxygen overvoltage characteristics. Removal of oxygen from results in a new crystalline compound , with a pseudo‐face‐centered cubic orthorhombic lattice. This new compound is a nonconductor. The influence of the oxygen content of the lead oxides on their electrochemical behavior is discussed.