Photocatalytic degradation of levofloxacin by ternary Ag2CO3/CeO2/AgBr photocatalyst under visible-light irradiation: Degradation pathways, mineralization ability, and an accelerated interfacial charge transfer process study

Construction of highly efficient ternary photocatalytic systems is strongly attracting the attention of researchers. In this study, a novel ternary Ag2CO3/CeO2/AgBr photocatalyst with a double Z-scheme configuration was fabricated by in situ loading of Ag2CO3 onto CeO2 spindles and subsequently via an acid corrosion process. The ternary Ag2CO3/CeO2/AgBr composites exhibited enhanced photocatalytic activity for the photodegradation of levofloxacin (LVF) under visible light irradiation. Three-dimensional excitation-emission matrix fluorescence spectra revealed that the structure of LVF could be destroyed from the fluorescence point of view; liquid chromatograph-mass spectrometer tests indicated that LVF can be degraded via different pathways; a total organic carbon study showed that LVF could be effectively mineralized. Transient photocurrent response, photoluminescence, and electrochemical impedance spectroscopy indicated that ternary Ag2CO3/CeO2/AgBr composites had fast photoinduced charge separation efficiency. Active-species-trapping experiments and an electron spin resonance technique confirmed that h(+), O-center dot(2)-, and (OH)-O-center dot all participated in a photodegradation process. On the basic of various performance characterization and experimental results, a double Z-scheme photocatalytic mechanism was proposed. It is expected that the ternary Ag2CO3/CeO2/AgBr composites can be used as a promising photocatalyst for energy conversion and environmental remediation. This work could provide a new approach to constructing ternary hybrid photocatalysts and a comprehensive understanding of the degradation pathways for LVF. (C) 2017 Elsevier Inc. All rights reserved.