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

Abstract

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 (λ > 420 nm). The highest activity was observed for 1.0% Bi₂O₃/15% Si–TiO₂ calcined at 500 °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) were also found to be the most reactive species in the photocatalytic degradation