Electrochimica Acta, Vol.40, No.2, 175-179, 1995
Semiconducting Properties of the Anodic Pb(II) Oxide Film in Alkaline-Solution
The semiconducting properties of the anodic film formed on Pb in 0.1 M NaOH solution (60 degrees C) at 0.2 V (vs. Hg/HgO) have been investigated by the ac impedance and photocurrent methods at room temperature. The Mott-Schottky plots show that the anodic film is an n-type semiconductor. Values of flatband potential for the anodic film anodized for 0.5 and 1.0 h are -0.79 and -0.78 V (vs. Hg/HgO), and the corresponding values of donor density are 3.73 x 10(16) and 5.42 x 10(16) cm(-3), respectively. The analysis of the photocurrent spectra shows the band gap width of the anodic film for indirect transitions as 1.88 eV. The relation between photocurrent and applied potential for the anodic film has been analyzed by the Gartner model, from which the values of the absorption coefficients of t-PbO were found to be much larger than that of t-PbO single crystals. This may be caused by the extrinsic photogeneration of electron-hole pairs.
Keywords:SULFURIC-ACID-SOLUTION;LEAD ELECTRODE;PHOTOELECTROCHEMICAL PROPERTIES;OXIDATION;ANTIMONY;LAYER;H2SO4