Enhanced visible-light response of natural V-bearing rutile by annealing under argon

摘要

Like synthetic V-doped TiO_2, natural semiconducting V-bearing rutile (TiO_2) has potential capability for visible-light absorption. The traditional modification for the synthetic V-doped TiO_2 was to enhance the sample's visible-light absorption by increasing the doping concentration. This paper demonstrates that the visible-light absorption of natural rutile with low V doping concentration (1.0 mol%) is significantly enhanced simply through annealing under argon. In the visible-light region of 400-750 nm, the integral absorbance of rutile treated at 1173 K increased by around 63 % compared to untreated rutile. Electronic paramagnetic resonance (EPR) measurements indicated that argon annealing induced a substantial increase of V~(4+) as an active state of V doping ions for the visible-light absorption. This argon annealing can provide a simple modification method for enhancing the visible-light absorption of V-doped TiO_2.