Construction of a Hollow Bioi/Tio2/Zif-8 Heterojunction : Enhanced Photocatalytic Performance for Norfloxacin Degradation and Mechanistic Insight

The overuse of norfloxacin (NOR) has attracted wide attention because of the persistence and bio-accumulate in ecosystems and the negative impacts on human health. To solve the environmental issue, BiOI/TiO 2 p-n heterojunctions were developed and decorated with a porous metal organic framework ZIF-8 to obtain a novel hollow BiOI/TiO 2 /ZIF-8 heterojunctions, which were further characterized by XRD, SEM, HRTEM, XPS, BET, UV-vis DRS, photoluminescence, ESR, photocurrent and EIS analyses. The BiOI/TiO 2 /ZIF-8 heterojunctions exhibited evidently improved photocatalytic performance compared to pristine BiOI, TiO 2 and BiOI/TiO 2 composites under visible light irradiation. ZIF-8 plays a key role in both the enhancement of adsorption and the photocatalytic activity in NOR removal. ·O 2 - and ·OH radicals were the two dominating active species in the photocatalytic process according to the trapping experiments. Large specific surface area, highly effective charge carrier migration with inhibiting recombination, and more negative conduction band to generate the active ·O 2 - radicals resulted in the superior photocatalytic activity of BiOI/TiO 2 /ZIF-8 heterojunction compared with pristine and binary samples. This work provides a new idea to design a kind of photocatalytic heterostructure with more active species for potential application in the field of environmental treatment