Recyclable (Fe3O4-NaYF4:Yb,Tm)@TiO2 nanocomposites with near-infrared enhanced photocatalytic activity

Abstract

Herein, the design and synthesis of a multifunctional (Fe₃O₄-NaYF₄:Yb,Tm)@TiO₂ photocatalyst through a facile sol–gel process combined with electrostatic self-assembly has been reported. Particularly, as an upconversion sensor, NaYF₄:Yb,Tm nanoparticles have the ability to convert near-infrared (NIR) light into ultraviolet (UV) emissions, so that the catalytic body TiO₂ can indirectly utilize the NIR part of sunlight but not UV light. The excellent photocatalytic activity of the hybrid samples is evaluated using a model of the degradation of methylene blue (MB). Most importantly, the obtained materials exhibit remarkable magnetic properties because of the addition of a magnetic component (Fe₃O₄), therefore, the photocatalysts possess desired recyclability and reusability, which is significant for actual applications. Finally, the possible photocatalysis mechanism of the nanohybrids is discussed and hydroxyl radicals (OH˙) are confirmed as the main reactive species.