Self-assembly of Bi_xTi_(1-x)O2 visible photocatalyst with core-shell structure and enhanced activity

摘要

Mesoporous Bi_xTi_(1-x)O2 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 Bi_xTi_(1-x)O2 spheres exhibited much higher activity than the undoped TiO2, the Bi2O3/TiO2 obtained by impregnating the TiO2 with Bi(NO3)3 solution, and the Bi_xTi_(1-x)O2 after being ground during photodegradation of p-chlorophenol under visible light irradiation. Meanwhile, the Bi_xTi_(1-x)O2 could be used repetitively for 10 times owing to the high hydrothermal stability and the absence of Bi-leaching.