Surface analysis of anodic lead oxide films prepared in hot alkaline solutions

Lead oxide films such as alpha-PbO, beta-PbO and PbO2-x (x = 0-1) have been prepared on a Pb electrode by anodic oxidation in hot alkaline solutions and characterized by X-ray photoelectron spectroscopy (XPS). Anodic oxidation of a Pb electrode in hot alkaline solution facilitates selective growth of specific lead oxide phases depending upon the anodization potential. The O Is core level binding energy (B.E.) values of both alpha and beta-PbO phases were identical (530.1 eV), whereas PbO2-x film exhibited a value about 0.7 eV lower (529.4 eV). These values are overall higher than those reported in the literature. In addition, the literature data for the O Is B.E. values were almost the same for all lead oxide phases irrespective of the Pb oxidation state. The present results which exhibit an overall higher O Is B.E. for these films with a lower B.E. value for PbO2-x film in comparison with PbO films appears to be a new finding. Furthermore, the controversy existing in the literature on the interpretation of O is core level spectra of various lead oxide phases is also reviewed. (C) 1998 Elsevier Science B.V.