Fabrication of Bi2WO6-x@MOF via surface engineering for efficient photocatalytic degradation of fluoroquinolone antibiotics

A Bi 2 WO 6-x @MOF heterostructure is fabricated via surface engineering combining oxygen vacancies with in-situ MOF growth. • The Bi–O bridged heterointerface effectively shields surface oxygen vacancies from oxidative deactivation. • Directional charge transfer from Bi 2 WO 6-x to Bi-MOF fragments significantly suppresses photogenerated carrier recombination. • Superoxide anion radicals (·O 2 - ) are identified as the dominant reactive species driving antibiotic mineralization. Oxygen vacancies (Ov) can significantly enhance the photocatalytic activity of metal oxide semiconductors, yet their susceptibility to oxidative deactivation under reaction conditions severely limits long-term stability. Herein, we report a surface engineering strategy to construct a Bi 2 WO 6-x @MOF heterostructure, where Bi-MOF layer is grown in situ onto oxygen-deficient bismuth tungstate nanosheets. The Bi–O bridged heterointerface not only preserves the surface Ov from oxidative erosion but also promotes directional charge transfer from the oxide substrate to the MOF particulates, as evidenced by XPS, EPR, and time-resolved photoluminescence. The Bi 2 WO 6-x @MOF achieves a levofloxacin degradation efficiency of 73.1% under simulated solar irradiation, substantially outperforming pristine Bi 2 WO 6 (44.4%) and defective Bi 2 WO 6-x (53.7%), while maintaining stable activity over five recycling runs. Mechanistic studies, including radical trapping and EPR spectroscopy, identify superoxide anion radicals (·O 2 - ) as the dominant reactive species. DFT calculations further reveal that interfacial Bi–O coordination lowers O 2 adsorption energy barrier to 0.477 eV on the Bi 2 WO 6-x @MOF and facilitates the formation of ·O 2 - . This work demonstrates that MOF encapsulation, when coupled with proper electronic modulation, offers a robust route to simultaneously stabilize defects and boost photocatalytic performance for antibiotic wastewater treatment. Download: Download high-res image (92KB) Download: Download full-size image