Self-assembly of BixTi1-xO2 visible photocatalyst with core-shell structure and enhanced activity

Mesoporous BixTi1-xO2 spheres with core-shell chamber were prepared by alcoholysis under solvothermal conditions. The cross-condensation between Ti-OH and Bi-OH ensured complete incorporation of Bi-dopants into TiO2 lattice, though Bi atom is much bigger than Ti. Meanwhile, the aggregation of titania building clusters into spheres and their subsequent reactions including dissolution and re-deposition processes lead to the hollow spheres with tunable interior structure. The Bi-doping induced strong spectral response in visible region owing to the formation of narrow intermediate energy band gaps. Meanwhile, multiple reflections within the sphere interior voids promoted the light absorbance. As a result, the as-prepared BixTi1-xO2 spheres exhibited much higher activity than the undoped TiO2, the Bi2O3/TiO2 obtained by impregnating the TiO2 with Bi(NO3)(3) solution, and the BixTi1-xO2 after being ground during photodegradation of p-chlorophenol under visible light irradiation. Meanwhile, the BixTi1-xO2 could be used repetitively for 10 times owing to the high hydrothermal stability and the absence of Bi-leaching. (C) 2009 Elsevier B.V. All rights reserved.