Anodic oxidation of lead indium alloys in sulphate solution. The electrocatalysis of the anodic oxygen transfer reaction.

In order to enhance the electrocatalytic activity of the lead dioxide towards the anodic oxygen transfer reaction, the anodic oxide layer formed in the lead dioxide potential region was modified by alloying lead with indium. First, XRD and SEM analyses have shown a weak influence of the indium on the structure and the morphology of the modified anodic oxide layer, suggesting that the doping element is introduced in the PbO2 lattice by the substitution of Pb+IV by In+III ion. Secondly, the oxygen evolution reaction (OER) was studied in neutral sulphate solution in terms of oxygen overvoltage and Tafel plot measurements. The influence of the indium content in the PbO2 layer towards the electrocatalysis of the anodic oxygen transfer reaction during the oxidation of DMSO chosen as model molecule was outlined. The enhancement of the anodic O-transfer reaction with the increase of the indium content is confirmed by the results of the phenol electrochemical oxidation. The improvement of the electrocatalytic effect can be ascribed to a better interaction between the active oxygen surface sites and the adsorbed organic molecules.