Synergistic defect engineering of Bi-MOF/Bi2O2[BO2(OH)] heterojunctions via UV-induced oxygen vacancies for efficient ciprofloxacin degradation

Defect engineering coupled with heterojunction construction represents a pivotal strategy for optimizing the charge separation dynamics of photocatalysts. Herein, we report the fabrication of a novel Z-scheme heterojunction composed of bismuth-based metal-organic frameworks (NOTT-220) and layered Bi 2 O 2 [BO 2 (OH)] nanosheets via a hydrothermal approach. To further potentiate the photocatalytic activity, surface oxygen vacancies (OVs) were precisely introduced into the heterostructure through controlled ultraviolet (UV) irradiation. This defect-rich engineering strategy significantly broadened the visible-light absorption range and facilitated the separation of photogenerated carriers. Consequently, the optimized catalyst (OVs-BN-20) exhibited a superior photocatalytic reaction rate constant of 0.8133 min −1 , achieving 95.9% degradation rate of CIP within 2 h. Detailed mechanistic investigations, including liquid chromatography-mass spectrometry (LC-MS) and electron spin resonance (ESR), elucidated the degradation pathways and confirmed the synergistic role of superoxide radicals (·O 2 -) and photogenerated holes (h + ). This work not only provides a facile pathway for designing defect-modulated Z-scheme photocatalysts but also offers profound insights into the mineralization mechanisms of persistent antibiotic pollutants.