Hydrothermal Synthesis of Porous Ag2S Sensitized TiO2 Catalysts and Their Photocatalytic Activities in the Visible Light Range

Porous Ag2S sensitized TiO2 catalysts were synthesized by the hydrothermal process. The crystallization and porous structure of the Ag2S/TiO2 composite photocatalysts were investigated by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, UV-Vis diffuse reflectance spectroscopy, and N-2 adsorption. The Ag2S/TiO2 composites were mainly composed of anatase TiO2 and acanthite Ag2S. The absorption edge wavelengths of TiO2 and the Ag2S/TiO2 composite prepared with 3 mmol Na2S center dot 5H(2)O were 400 and 800 nm, respectively, that is, the absorption edge of the composite had a pronounced red shift. The photocatalytic activity under visible light was investigated by the degradation of methylene blue with a UV-Vis spectrophotometer. The photocatalytic activities under visible light of the Ag2S/TiO2 photocatalysts were much higher than that of TiO2.