Bi2O3-Modified Rice-Like Brookite TiO2 for Enhancing the Photocatalytic Activity under Visible-Light Irradiation

Abstract

Brookite TiO₂ is a metastable crystalline phase, which is difficult to prepare manually. In this study, brookite TiO₂ with controllable morphology was synthesized by a simple hydrothermal method. The prepared brookite TiO₂ was a complete rice-like granular particle with a smooth surface and sharp edges at the tip of both ends. And the diameter of an individual brookite TiO₂ was approximately 200 nm. Then, to improve the photocatalytic degradation performance of brookite TiO₂, we prepared Bi₂O₃/brookite TiO₂ nanocomposites. After Bi₂O₃ composite, the crystalline phase of brookite TiO₂ did not change, and still maintained high purity and crystallinity. The Bi₂O₃ nanoparticles were dispersed on the surface of brookite TiO₂, forming heterogeneous structures in close contact. The Bi₂O₃/brookite TiO₂ nanocomposite exhibited a significantly higher degradation rate of ofloxacin (20 mg L⁻¹) under visible light (300 W Xenon lamp, λ ≥ 400 nm) compared to pure brookite TiO₂. The photocatalytic activity of 5 mol% Bi₂O₃/brookite TiO₂ was the best, the degradation rate of OFX reached 90.7%. The enhancement of photocatalytic activity of Bi₂O₃/brookite TiO₂ nanocomposites was attributed to the formation of Bi₂O₃/brookite TiO₂ heterojunction, which accelerated the photogenerated charge-hole separation. This study provided theoretical support for efficient photocatalytic degradation of pollutants.