THE IDENTIFICATION OF THE REDUCTION PEAK OF TETRAGONAL PBO ON PB BY LASER RAMAN-SCATTERING AND X-RAY-DIFFRACTION

The debate about the reaction causing the cathodic peak at about -800 mV on the linear sweep voltammogram of a Pb electrode in H2SO4 solution is still unsettled. In this paper, ex situ laser Raman scattering and in and ex situ x-ray diffraction techniques are used to identity the peak, which proved to be the reduction of tetragonal PbO according to the changes of the diagnostic diffraction lines with d = 3.12, 2.81, and 1.87 angstrom and Raman bands at 148 and 343 cm-1. Electrochemically inert PbSO4 also exists on the Pb surface.