posted on 2024-01-04, 17:35authored byYongjun Peng, Jialiang Lin, Ji-Liang Niu, Xiaolan Guo, Yazhen Chen, Tongke Hu, Jianhua Cheng, Yongyou Hu
Heterojunction structure and ion doping techniques are
viable tactics
in facilitating the generation and separation of photogenerated electrons
and holes in photocatalysis. In the current study, a novel Bi ion-doped
MIL-68(In,Bi)-NH2@BiOBr (MIBN@BOB) type-II heterojunction
was first synthesized in a one-step solvothermal reaction. Doping
of Bi ions not only broadened the light-sensing range but also provided
reliable anchor sites for the in situ growth of BiOBr. Meanwhile,
the heterostructure supplied new channels for photogenerated carriers,
accelerating the transfer and inhibiting the recombination of photogenerated
electron–hole. The obtained MIBN@BOB exhibited enhanced photocatalytic
performance (91.1%) than MIL-68(In)-NH2 (40.8%) and BiOBr
(57.5%) in ciprofloxacin (CIP) degradation under visible light, with
excellent reusability. Photocatalysts were characterized in detail,
and a series of photoelectrochemical tests were utilized to analyze
the photoelectric properties. MIBN@BOB were deduced to conform the
electron conduction mechanism of conventional type-II heterojunctions.
More importantly, based on the above experiments and density functional
theory (DFT) calculation, BiOBr-Bi in MIBN@BOB can serve as the major
active sites of CIP enrichment, and •O2– and 1O2 generated at the BiOBr interface can
react with the adsorbed CIP directly. Lastly, the possible degradation
products and pathways of CIP were analyzed by liquid chromatography-tandem
mass spectrometry (LC/MS/MS). This study provides a reference for
the construction of ion-doping-modified metal–organic framework
(MOF)-based heterojunction photocatalysts and their application in
antibiotic removal.