Efficient Visible-Light-Driven Photocatalytic Degradation with Bi2O3 Coupling Silica Doped TiO2

A new TiO2-based visible light photocatalyst (Bi2O3/Si TiO2) was synthesized by both Bi2O3 coupling and Si doping via a two-step method. The structural, morphological, light absorption, and photocatalytic properties of as-prepared samples were studied using various spectroscopic and analytical techniques. The results showed that Bi2O3/Si-TiO2 catalysts held an anatase phase and possessed high thermal stability. The doped Si was woven into the lattice of TiO2, and its content had a significant effect on the surface area and the crystal size of Bi2O3/Si-TiO2. The introduced Bi species mainly existed as oxides on the surface of TiO2 particles, and the Bi2O3 photosensitization extended the light absorption into the visible region. Bi2O3 coupling also favored the separation and transfer of photoinduced charge carriers to inhibit their recombination and Si doping enlarged the surface area of photocatalysts. Compared to bare TiO2, Bi2O3/TiO2, and Si-TiO2, Bi2O3/Si-TiO2 samples showed better activities for the degradation of methyl orange (MO) and bisphenol A (BPA) under visible light irradiation (lambda > 420 nm). The highest activity was observed for 1.0% Bi2O3/15% Si-TiO2 calcined at 500 degrees C. The superior performance was ascribed to the high surface area, the ability to absorb visible light, and the efficient charge separation associated with the synergetic effects of appropriate amounts of Si and Bi in the prepared samples. The adsorbed hydroxyl radicals ((OH)-O-center dot) were also found to be the most reactive species in the photocatalytic degradation.