Synthesis and characterization of mesoporous Bi/TiO2 nanoparticles with high photocatalytic activity under visible light

Under the strategies of doping to extend the absorptive response region of a semiconductor and fabricating a mesoporous structure with large specific surface area to enhance the photocatalytic property, an efficient visible-light-driven photocatalyst of bismuth-doped titanium dioxide (Bi/TiO2) was prepared via a facile sol-gel route. The resulting materials were characterized by powder x-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG), UV–vis diffuse reflectance spectrum (DRS), and N2 adsorption–desorption measurements (BET). The photocatalytic performances of as-synthesized particles were monitored by degradation of 2,4-dichlorophenol (2,4-DCP) in transparent aqueous solutions under visible light illumination. The results revealed that mesoporous PEG-modified Bi-doped TiO2 exhibited much higher photocatalytic activities than Bi-doped TiO2 without modification, and noticeably the optimized doping level was increased from 2 to 4 mol%. The visible-light photocatalytic activity enhancement of PEG-modified Bi-doped TiO2 could be attributed to appropriate proportional mixed crystal phase, large surface area, porosity, mesoporous network with interconnected small nanocrystals, and its strong absorption in the visible region.