Construction of oxygen vacancy-rich NCDs@Ov-MIL-53 via sacrificial ligand strategy for enhanced antibiotic removal

Metal-organic frameworks (MOFs) have attracted wide attention owing to unique structural advantages and excellent catalytic properties, yet the inherent poor conductivity and limited visible-light responsiveness constrain their practical applications. Herein, a dual modification strategy based on the thermal decomposition of ligands to construct nitrogen-doped carbon dots (NCDs) decorated MIL-53(Fe) with oxygen vacancies (Ov) is reported in this work. By selectively removing thermally unstable ligands from the dual-ligand MIL-53(Fe) at elevated temperatures, oxygen vacancies were successfully introduced into the MOF framework while maintaining structural integrity. The subsequently integrated amino-rich NCDs facilitated interfacial charge transfer and contributed to improved light utilization. The optimized NCDs@Ov-MIL-53 composites exhibited excellent photocatalytic performance for the degradation of tetracycline. Under visible light irradiation, a removal rate of 93.72 % was achieved within 60 min, which was 2.8 times higher than that of the original MIL-53 (Fe). Systematic characterization showed that oxygen vacancies promoted carrier separation and created active sites, while NCDs acted as electron acceptors. A new insight into defect engineering through ligand-selective pyrolysis is provided by this work and offers a viable strategy for the design of MOF-based photocatalysts for environmental applications.