Enhanced UV–Vis–NIR composite photocatalysis of NaBiF4:Yb3+, Tm3+ upconversion nanoparticles loaded on Bi2WO6 microspheres

Abstract

NIR light accounts for 50% of total solar energy, but only a small amount of the energy is applied to photocatalytic reactions. The incorporation of upconversion nanoparticles with semiconductor materials is an effective tactics to exploit NIR-driven photocatalyst. In this work, we report a composite material that can convert NIR light into UV–Vis photons. The light conversion material is composed of NaBiF4: Yb3+, Tm3+ up-conversion nanocrystals. The petal-like Bi2WO6 is used as a semiconductor photocatalyst to directly degrade model pollutants, such as RhB. By controlling the morphology of Bi2WO6, the contact area between the semiconductor photocatalyst and the pollutant molecules is increased. The preparation of “double bismuth” composite material NaBiF4:Yb3+, Tm3+/Bi2WO6 provides the possibility to make full use of sunlight. Under the excitation of simulated sunlight, the photocatalyst of NaBiF4:Yb3+, Tm3+/Bi2WO6 reaches the highest degradation efficiency of 98% in 27 ​min. Compared with Bi2WO6, the prepared composite photocatalyst shows better photocatalytic performance, which is attributed to the effective energy transfer between NaBiF4:Yb3+,Tm3+ and Bi2WO6. The capture tests were used to detect active species used in the degradation process. After four continuous photocatalytic cycles, about 95% of RhB solution is degraded. Under the simulated solar light illumination, the photocatalytic mechanism of the composite photocatalyst is discussed. The results propose a promising system to improve the photocatalytic activity through the efficient use of sunlight.