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

Abstract

Porous Ag 2 S sensitized TiO 2 catalysts were synthesized by the hydrothermal process. The crystallization and porous structure of the Ag 2 S/TiO 2 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 Ag 2 S/TiO 2 composites were mainly composed of anatase TiO 2 and acanthite Ag 2 S. The absorption edge wavelengths of TiO 2 and the Ag 2 S/TiO 2 composite prepared with 3 mmol Na 2 S·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 Ag 2 S/TiO 2 photocatalysts were much higher than that of TiO 2 . The hydrothermal synthesis and visible light photocatalytic activity of Ag 2 S/TiO 2 catalysts fabricated with Ag 2 S as photosensitizer are reported. The improved catalytic activity was due to the excellent electrical properties of the Ag 2 S semiconductor that was well dispersed.