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

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 NaBiF 4 : Yb 3+ , Tm 3+ up-conversion nanocrystals . The petal-like Bi 2 WO 6 is used as a semiconductor photocatalyst to directly degrade model pollutants, such as RhB. By controlling the morphology of Bi 2 WO 6 , the contact area between the semiconductor photocatalyst and the pollutant molecules is increased. The preparation of “double bismuth” composite material NaBiF 4 :Yb 3+ , Tm 3+ /Bi 2 WO 6 provides the possibility to make full use of sunlight. Under the excitation of simulated sunlight, the photocatalyst of NaBiF 4 :Yb 3+ , Tm 3+ /Bi 2 WO 6 reaches the highest degradation efficiency of 98% in 27 ​min. Compared with Bi 2 WO 6 , the prepared composite photocatalyst shows better photocatalytic performance, which is attributed to the effective energy transfer between NaBiF 4 :Yb 3+ ,Tm 3+ and Bi 2 WO 6 . 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.