The cathodic reduction behavior of the anodic Pb(II) oxides film formed on Pb for 2 h in 4.5 mol/L H_2SO_4 solution at 0.9 V (vs. Hg/Hg_2SO_4) has been investigated by X-ray diffraction method (XRD), photocurrent measurements, linear sweep voltammetry (LSV) and open circuit decay curve (OCD). The results show that: (1) The major components of the anodic Pb(II) oxides film are PbO particles and PbO· PbSO_4 particles, and the interstitial liquid may serve as the major passage for ion transportation during the reduction of the anodic film. (2) The anodic Pb(II) oxides film is reduced via a dissolution- precipitation mechanism during the negative LSV. At first, the surface layer of the PbO particles is reduced to the metal Pb, and then the PbO and PbO·PbSO_4 particles are reduced together, when the metal Pb in the surface layer of the PbO particles meets the PbO·PbSO_4 particles, and the reduction of PbO·PbSO_4 particles is slightly faster than that of the PbO particles.

Key words: LEAD, PHOTOCURRENT, DISSOLUTION, SEDIMENTATION, ELECTRODE