Novel Tm3+ and Yb3+ co-doped bismuth tungstate up-conversion photocatalyst with greatly improved photocatalytic properties

Abstract Tm 3+ and Yb 3+ co-doped Bi 2 WO 6 up-conversion photocatalysts (Tm 3+ /Yb 3+ :Bi 2 WO 6 ) were synthesized via co-precipitation route at different calcination temperatures. Doping Tm 3+ and Yb 3+ into Bi 2 WO 6 lattice and substituting for the fractional Bi 3+ were successfully confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The morphology and optical property of the obtained samples were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS) and up-conversion luminescence spectra (UC-PL). The photocatalytic results revealed that the Tm 3+ /Yb 3+ :Bi 2 WO 6 exhibited a much superior photocatalytic activity than the pure Bi 2 WO 6 and commercial Degussa P25 for the degradation of rhodamine B (RhB), and the degradation rate reached 97.6% in 25 min. The effects of Tm 3+ and Yb 3+ on the photocatalytic activity of Bi 2 WO 6 were studied in detail. The improved photocatalytic activity of Bi 2 WO 6 could be attributed to the efficient energy transfer between Tm 3+ /Yb 3+ and Bi 2 WO 6 via infrared to visible up-conversion and the reduced recombination rate of photogenerated electron-hole pairs through co-doping of Tm 3+ /Yb 3+ on Bi 2 WO 6 nanopaticles.