UiO-66-mediated Bi2WO6/AgI heterojunction photocatalyst for efficient visible-light-driven tetracycline degradation

The persistence and removal of antibiotic residues in aquatic environments represent a global environmental challenge. In this study, a novel ternary Bi 2 WO 6 /UiO-66/AgI heterojunction photocatalyst was designed and constructed for the deep removal of tetracycline (TC). AgI nanoparticles and Bi 2 WO 6 nanosheets were in situ anchored onto a porous UiO-66 framework, successfully integrating high adsorption capacity, visible-light response, and efficient charge separation. It was demonstrated that the composite, when exposed to visible light, exhibited a significantly enhanced level of TC degradation activity in comparison with its single- and binary-component counterparts. Mechanistic investigations revealed that UiO-66 not only served as an adsorptive substrate to concentrate pollutants but also functioned as an electron transfer mediator, promoting a direct Z-scheme charge transfer pathway between Bi 2 WO 6 and AgI. This configuration effectively suppressed charge-carrier recombination and enhanced the generation of reactive oxygen species ·O 2 − , ·OH and h + ). The proposed reaction pathway was confirmed by radical-trapping experiments and electron paramagnetic resonance (EPR) spectroscopy. Additionally, this composite material demonstrated favourable performance in stability and toxicity assessments. This work provides a new design concept for metal–organic framework-based composite photocatalysts and elucidates their potential application in synergistic adsorption–photocatalytic degradation of organic pollutants in water treatment. Graphical abstract