A novel Ag2O/CeO2 heterojunction photocatalysts for photocatalytic degradation of enrofloxacin: possible degradation pathways, mineralization activity and an in depth mechanism insight

Abstract

Semiconductor photocatalysis has been considered as one of the most promising technologies for the removal of antibiotics from aqueous solutions. In this study, Ag2O/CeO2p-n heterojuction photocatalysts were fabricated by an in situ loading Ag2CO3 on CeO2 spindles and subsequent via a thermal decomposition process. The Ag2O/CeO2 composites exhibited enhanced photocatalytic activity for the photodegradation of enrofloxacin (EFA) under visible light irradiation. A plausible degradation pathway for EFA was proposed. The Ag2O/CeO2 heterojuction photocatalysts exhibited the high mineralization ability towards the EFA molecule degradation based on three-dimensional excitation–emission matrix fluorescence spectroscopy (3D EEMs) and total organic carbon (TOC) analysis. Transient photocurrent response, PL spectrum and EIS indicate high photoinduced charge separation efficiency possess in Ag2O/CeO2 composites. Active species trapping experiments and ESR technique confirmed that h+ and O2 were the main active groups involved in photo-degradation of organic pollutants. Through the combination of various performance characterization and experimental results, a possible photocatalytic mechanism was proposed. Moreover, the energy band alignments of Ag2O/CeO2 heterostructure were calculated, which provided strong support for the proposed mechanism. This work could provide a new approach to construct new heterojunction photocatalysts and a deeper insight for the heterojunction catalyst.