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

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, lambda >= 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.