ELECTROSYNTHESIS OF LEAD-OXIDE FILM ON A LEAD ELECTRODE IN ALKALINE-SOLUTION BY A POTENTIODYNAMIC METHOD - ITS CHARACTERIZATION AND PHOTOELECTROCHEMICAL PROPERTIES

A lead electrode was anodized by potential cycling for various times i n the region -0.35 to +0.75 V/SCE (sweep rate, 200 mVs-1) in 0.1 M NaO H + 0.1 M Na2SO4 at 80-degrees-C. The anodic lead oxide films obtained were found to contain mostly alpha-PbO with varying amounts of alpha- PbO2 and to show improved semiconducting behaviour. The lead oxide fil ms were characterized by X-ray diffraction UV-visible reflectance, las er Raman spectroscopy, X-ray photoelectron spectroscopy, scanning elec tron microscopy, and impedance and photoelectrochemical techniques. Th e oxide growth rate under the conditions given above is found to be hi gh, yielding a film about 10 mum thick in 1-2 h of potential cycling t ime. The lead oxide film thus formed shows a varying photocurrent dens ity with increase in potential cycling time. This behaviour has been a ttributed to changes in the composition and thickness of the oxide fil m. The lead oxide film obtained by anodization for 1 h showed a 15.1% quantum yield in 0.1 M Fe(CN)64- redox electrolyte and a solar to elec trical energy conversion efficiency of 0.33%.