Oxygen-vacancy-mediated energy transfer for singlet oxygen generation by diketone-anchored MIL-125

[Display omitted] •Post-synthetic modification with β-diketone is a useful strategy to fabricate MOFs.•Diketone anchoring improves the ability of MIL-125 to generate 1O2.•Diketone-anchored MIL-125 generate 1O2 via an energy transfer pathway.•Diketone-derived oxygen vacancies account for the enhanced energy transfer. The importance of singlet oxygen (1O2) in synthesis of fine chemicals, inactivation of viruses and bacteria, degradation of pollutants, and photodynamic therapy has promoted the research on photocatalytic generation of 1O2. Metal-organic frameworks (MOFs), owing to the tunable structure, are good candidate photocatalysts for 1O2 generation. However, due to the poor visible-light absorption capacity and the invalid recombination of charge carriers, the 1O2 generation yields of most MOFs are still limited. Here, we demonstrate that β-diketone anchoring could improve the photocatalytic generation of 1O2 by MIL-125 through enhanced energy transfer. The enhanced energy transfer was attributed to both the narrowed bandgap and the diketone-derived oxygen vacancies, which function as the trapping sites for charge carriers. The results here shed light on the generation of 1O2 by visible-light-responsive MOFs and provide a new strategy for the design of MOFs-based photocatalysts.