PbS-sensitized K2Ti4O9 composite: Preparation and photocatalytic properties for hydrogen evolution under visible light irradiation

PbS-sensitized K2Ti4O9 composite photo-catalysts (hereafter designated as K2Ti4O9) were prepared by a facile deposition-precipitation method. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence measurement (PL). The photo-catalytic activities were investigated under visible light irradiation. The results indicated that the size of PbS, which uniformly scattered on the surface of K2Ti4O9, distribute in the range of 50-100 nm. The absorption edge of K2Ti4O9 shifted to the visible light region and recombination of electrons and holes was suppressed after the deposition of PbS. The composite photo-catalyst loading 25 wt.% PbS synthesized by deposition-precipitation method showed the highest photo-catalytic activity. The amount of hydrogen evolution is 1.85 mmol/g after 3 h irradiation over 0.5 g catalyst in the reaction system containing Na2S-Na2SO3-KOH aqueous solution. Finally, the mechanism of the photo-catalysis was discussed. (C) 2012 Elsevier B.V. All rights reserved.