Photochromism of WO3 Colloids Combined with TiO2 Nanoparticles

WO 3 and TiO 2 colloids were synthesized by the forced hydrolysis technique, and different amounts of the TiO 2 colloids were added to WO 3 colloids under sonication to get stable combined TiO 2 and WO 3 colloids (WO 3 /TiO 2 ). The experimental results indicate that the UV-light coloration of WO 3 colloids can be improved greatly after the TiO 2 combination. When the molar ratio of TiO 2 and WO 3 is about 1:40, ΔOD at 900 nm for WO 3 /TiO 2 colloids is about 12.7 times that of WO 3 colloids. The improvement effect increases with the increased concentration of TiO 2 in the composite colloids, and the maximum enhancement can increase more than 50-fold. It is shown that after the combination, the recombination of photogenerated carriers is suppressed efficiently, and more electrons can be trapped within the band gap of WO 3 to contribute to the coloration process.