Novel simulated sunlight-driven NaYF4:Yb,Tm@MIL-53(Fe) nanorods photocatalysts for degradation of organic pollutants and enhanced antibacterial activity

We developed new NaYF4:Yb,Tm@MIL-53(Fe) (UM) and NaYF4:Yb,Tm@MIL-53(Fe)@Rf (UMR) rods for efficient photocatalytic oxidation of organic matter and bacteria in wastewater. These rods feature core–shell mesoporous structures and broad spectrum-response capabilities, achieved through a self-assembly method. The NaYF4:Yb,Tm nanorods were synthesized hydrothermally. UM was obtained by assembling Polyvinylpyrrolidone-modified NaYF4:Yb,Tm under stirring and heating conditions, while UMR was synthesized by adding riboflavin (Rf) during stirring. UM demonstrated the ability to degrade 92.2% of RhB under simulated sunlight, with 81.8% degradation even after four recycling cycles. Superoxide radicals, hydroxyl radicals, electrons, and holes played crucial roles in the photocatalytic process. The outstanding performance of these nanophotocatalysts can be attributed to the interfacial electron transfer between upconversion nanorods (UCNRs) and the metal–organic framework (MOF), along with their unique core–shell mesoporous structure. Additionally, UMR exhibited excellent antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under simulated sunlight, as UCNRs activated the MOFs or Rf through fluorescence resonance energy transfer to enhance redox capability. Notably, the inhibition performance against S. aureus was superior, possibly due to the unique outer membrane structure present on E. coli. This work introduces a novel nanophotocatalyst for effective treatment of organic pollutants and pathogenic bacteria in wastewater.