Effect of SiO2 Content on the Catalytic Performance of SiO2-TiO2 Composite Photocatalyst

SiO2-TiO2 composite photocatalysts were synthesized by sol-gel method with different SiO2 content (mol%). The specific surface area, structure, the band gap, the relative surface hydroxyl content and the photo-induced charge separation rate of the photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (DRS), and surface photovoltage spectroscopy (SPS), respectively. The results show that the presence of SiO2 increases the specific surface area and the surface hydroxyl content, and influences the separation rate of photo-induced charge. The photocatalytic performance of SiO2-TiO2 for decolorization of methyl orange (MO) aqueous solution was investigated, the results show that SiO2-TiO2 composite photocatalyst with 16.7% SiO2 (mol%) possesses the best photocatalytic activity among the experimented compositions and the underlying mechanisms are discussed.