One-pot controllable synthesis of BiOBr/β-Bi2O3 nanocomposites with enhanced photocatalytic degradation of norfloxacin under simulated solar irradiation

Abstract

The low quantum yield and weak catalytic ability of bismuth oxyhalides retard their applications in photocatalytic degradation. To promote the performances of bismuth oxyhalides in photodegradation of antibiotics, a series of BiOBr/β-Bi2O3 nanocomposites was synthesized via a facile solvothermal process in which one-pot strategy was adopted to accomplish the purpose by adjusting the mole ratio of the bismuth and bromine. The formation of heterojunction at the BiOBr/β-Bi2O3 surface boundary was confirmed by XRD, PL, DRS, XPS and HR-TEM. The photocatalytic properties of these BiOBr/β-Bi2O3nanocomposites were evaluated by the photodegradation of norfloxacin under simulated sunlight irradiation. The BiOBr/β-Bi2O3 nanocomposites obtained at the molar ratio of 3:1 (Bi:Br) exhibit the best photodegradation activity. The photocurrent density of BiOBr/β-Bi2O3 nanocomposites (Bi:Br = 3:1) is twice higher than that of the pristine BiOBr, indicating the in-situ generating Bi2O3 on the BiOBr surface can effectively promote the separation of photogenerated electron-hole pairs and thus improving the photocatalytic performance. Furthermore, the photocatalytic mechanism was investigated using trapping experiments and ESR study. The results reveal that the matched energy band structure between BiOBr and Bi2O3 was able to facilitate the charge transfer and reduce the recombination of the photogenerated carriers. This work supplies a simple procedure for the in-situ growing Bi2O3 on Bi-based photocatalysts and an effective measurement for degrading norfloxacin.