Dual-responsive F-N-W-codoped TiO_2 nanoparticles with strong visible light response and low-temperature thermo-oxidation activity

摘要

F-N-W-codoped TiO_2 nanoparticles were successfully prepared by a sol-gel-mixing method without hydrothermal or calcining treatment. Effects of the F, N and W ion dosage concentration on crystallinity, morphology, grain size and chemical status of TiO_2 were investigated. The results showed that the appearance of F-N-W-codoped TiO_2 powders was uniformly spheroidal nanoparticles, whose average particle size was about 7 nm. The F-N-W-codoped TiO_2 nanoparticles owned high catalytic activity under visible light irradiation and low-temperature thermo-oxidation activity in the dark. The highest degradation rate of Rhodamine B dye was obtained by TiO_2 powders modified with 0.5 at.% W (N/W = 6/ 7) and 4.0 at.% F. Even in the dark, the degradation rate increased with the increasing of temperature. It was as high as 92% when the mixing liquid was kept at 60 ℃ for 2 h. The high catalytic activity of the F-N -W-codoped TiO_2 might result from larger specific surface area and high surface acidity because of surface F ions, the band gap narrowing caused by W_xTi_(1-x)O_2 or O-Ti-N, as well as lower recombination rate of charge carriers because of valence Variation of W ions (W~(6+) → W~(5+)) in the forbidden band.