Electron transfer channel in BiOBr/Bi2O3 heterojunction enhanced photocatalytic removal for fluoroquinolone antibiotics

Development of low-cost, nontoxic, highly efficient performance photocatalyst for water pollution control engineering is critical for environmental remediation. Herein, a three-dimensional polydopamine (PDA)/BiOBr/Bi2O3-450 microflowers is successfully constructed to realize high-flux charge transfer and efficient photocatalytic activity towards antibiotic degradation. The formation of C-O-Bi bonds within composites are well characterized by X-ray photoelectron spectroscopy (XPS) and In situ Fourier transform infrared (FTIR), which are employed as electron transfer channel to facilitate the extraction of photoelectrons from BiOBr to PDA. The presence of oxygen reduction reaction sites (i.e. pyridinic N and pyrrolic N) on PDA improves the photoelectron consumption and thus maximized the charge separation efficiency. On the other hand, the formation of BiOBr/Bi2O3 heterojunction is beneficial for the photoholes transfer from BiOBr to Bi2O3. As a result, the kinetic constant of norfloxacin degradation is 0.056 min−1 for PDA/BiOBr/Bi2O3-450, which is 2.54 times higher than that of pristine BiOBr. In addition, PDA/BiOBr/Bi2O3-450 exhibits the high reusability, retaining 91 % of the initial activity even after 5 repeated cycles or equivalent to 7.5 h of continuous irradiation. Briefly, this work throws light on enhancing photoelectron transfer and removal by interface control to dramatically improve the photocatalytic performance.