Anchoring NaYF4:Yb,Tm upconversion nanocrystals on concave MIL-53(Fe) octahedra for NIR-light enhanced photocatalysis

Abstract

Fe-Based MOFs can serve as low cost, stable, eco-friendly and visible light-driven photocatalysts, exhibiting promising applications in a broad range of fields. However, the present modification or semiconductor-coupling routes are still unable to extend their light response to the NIR region. Herein we present a microwave-assisted method to prepare MIL-53(Fe) octahedra with uniform concave facets. This unique structural geometry enables MIL-53(Fe) to trap upconversion nanocrystals (UCNPs) on their concave surface with a stable morphology. The developed MIL-53(Fe)/UCNP composites exhibit remarkable photocatalytic activity under NIR light and enhanced performance under Vis-NIR light. Through modifying the organic linkers with amino groups, both light absorption and utilization of upconverted emission of the composites can be enhanced, showing an improved activity. The formation and working mechanisms of the MOF/UCNP composite photocatalysts are also explored.