Effect of interfacial oxides on the electrochemical activity of lead dioxide film electrodes on a Ti substrate.

The electrochemical activities of PbO(2) thin-film electrodes were systematically studied with an oxygen-transfer reaction, i.e., the oxidation of thiourea. Five different types of PbO(2) film electrodes were prepared using various methods to investigate the influence of the interfacial oxide layer formed between the Ti substrate and the PbO(2) layer contacting the electrolyte. Among the electrodes tested, PbO(2) electrode prepared by minimizing the formation of the interfacial oxide by either the electrochemical or thermal decomposition method generally exhibited better electrochemical activity. From the results, it can be inferred that the enhanced electrochemical activity of the electrode is due to minimization of the interfacial resistance by the introduction of a metallic Pb layer between the Ti substrate and the PbO(2) layer, and to an increase in the roughness on the surface of the PbO(2) layer.