Photoelectrochemical degradation of Methylene Blue with beta-PbO2 electrodes driven by visible light irradiation.

Beta-PbO2 electrodes were prepared by electro-deposition and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and linear sweep voltammetry. We confirmed pure (beta-PbO2 crystals were on the electrode and it had a high oxygen evolution potential. The photoactivity and photoelectrochemical (PEC) properties of the beta-PbO2 electrode were investigated under visible light irradiation (lambda > 420 nm) for the decolorization of Methylene Blue. Pseudo first-order kinetics parameter (K(app)) for dye decolorization using the beta-PbO2 electrode achieved 6.71 x 10(-4) min(-1) under visible light irradiation, which indicated its excellent visible light-induced photoactivity. The K(app) of the PEC process was as much as 1.41 x 10(-3) min(-1) and was 1.71 times that of visible light irradiation or electrolysis even in the presence of the beta-PbO2 electrode. A significant synergetic effect was observed in the PEC system. We also employed TiO2 modified beta-PbO2 electrodes in this test, which revealed that the TiO2 immobilized on the beta-PbO2 electrode inhibited the visible light-induced PEC efficiency despite the amount of TiO2 used for electrode preparation. The beta-PbO2 electrode was also superior to the dimensionally stable anode (Ti/Ru(0.3)Ti(0.7)O2) in visible light-induced photoactivity and PEC efficiency.