In-situ prepared MIL-53(Fe)/BiOI photocatalyst for efficient degradation of tetracycline under visible-light driven photo-Fenton system: Investigation of performance and mechanism

In this work, a series of MIL-53(Fe)/BiOI composites were synthesized by a combined hydrothermal and facile co-precipitation method. The heterojunctions were further used as photocatalysts for tetracycline (TC) degradation in photo-Fenton system. The TC degradation rate constant for MIL-53(Fe)/BiOI (0.0906 min−1) was 2.1 and 2.3 times higher than that for MIL-53(Fe) (0.0432 min−1) and BiOI (0.0389 min−1), respectively. The photoelectrical characterization results suggested that the enhanced photocatalytic activity of the MIL-53(Fe)/BiOI composite was attributed to the high electron and holes separation efficiency. The scavenging experiment results and electron spin resonance analysis demonstrated that h+ and singlet oxygen were the main reactive species in the degradation process. The possible photo-Fenton degradation mechanism was further elucidated based on the band structures of MIL-53(Fe) and BiOI with the generation process of reactive species. This work provided a new idea to construct metal-organic-framework-based composite photocatalysts for photo-Fenton system, and it is also promising for the applications in environmental restoration and protection field.