Lanthanide doped bismuth tungstates: an investigation for LED and photocatalysis applications

Abstract

In this work, we studied optical, photocatalytic and photoelectrochemical properties of a series of lanthanide-doped double layered Aurivillius type bismuth oxides. The visible-light harvesting photocatalysts doped with Eu, Pr, Nd, Tm, Ho and Ce ions were synthesized by solid-state synthesis method. Doping amount was varied between 0.2-to-10 percent. X-ray diffraction (XRD) analysis revealed that lanthanide atoms were incorporated into the Bi2W2O9 lattice successfully up to 5%. Higher dopant ratios resulted in formation of secondary phases. Particles crystallized in micro-platelet morphology. Furthermore, luminescence of Pr 3+ and Eu 3+ ion doped catalysts are evaluated and the study showed that red emission intensity of Pr 3+ doped powder is 29 times higher than that of Eu 3+ doped ceramics. Lanthanide doped powders absorb in the visible regions. Especially, doping double layered bismuth oxide with Ce significantly narrowed down the band gap from ~3.3 eV to ~2.1 eV. Photoelectrochemical behaviour of the powders was also investigated and rare-earth dependent enhanced photocurrent production is demonstrated. Best photoelectrochemical response is achieved with Tm 3+ ion doped sample.