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

Abstract PbS-sensitized K 2 Ti 4 O 9 composite photo-catalysts (hereafter designated as PbS/K 2 Ti 4 O 9 ) 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 K 2 Ti 4 O 9 , distribute in the range of 50–100 nm. The absorption edge of K 2 Ti 4 O 9 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 Na 2 S–Na 2 SO 3 –KOH aqueous solution. Finally, the mechanism of the photo-catalysis was discussed.