Hollow α-Bi2O3/TiO2 nanotube arrays hierarchical heterojunction with strong interface interaction for efficient photocatalytic ciprofloxacin degradation

Abstract

Interfacial regulation for photocatalyst is considered as an effective strategy to enhance visible-light utilization and charges transfer. But it is still a great challenge for the conscious design of interfacial engineering. Herein, hollow α-Bi2O3/TiO2 nanotube arrays (α-Bi2O3/TNAs) hierarchical heterojunction was constructed to modulate the interface structure for efficient photocatalytic degradation of ciprofloxacin (CIP). The systematic characterization analysis, density functional theory (DFT) calculations and electron paramagnetic resonance spectra revealed that the Z-scheme charges transfer mechanism was affirmed between α-Bi2O3 and TNAs. The hierarchical tubular heterostructure was contributed to enhancing light absorption, and the strong interfacial interaction could promote the separation and transfer of photogenerated charges. The optimal α-Bi2O3/TNAs exhibited higher photocatalytic activity for CIP (73.9 %) than TNAs (25.3 %) under visible-light irradiation. The anions and natural organic matters could decline CIP removal owing to competing active sites or aggravating radicals consumption. The theoretical calculations further demonstrated that the staggered energy levels produced an internal electric field at heterojunction interface to promote charges transfer. Three degradation pathways of CIP were proposed based on DFT calculations and LC-MS. The photocatalytic degradation of CIP by α-Bi2O3/TNAs could effectively reduce its toxicity, and eventually alleviate the environmental hazards of antibiotics.