Abstract: TiO2/SiO2 microspheres with core-shell structure were synthesized by chemical adsorption and in situ hydrolysis using well-dispersed SiO2 microspheres as the template and tetrabutyl titanate as the precursor. The samples were calcined in a tube furnace under ammonia atmosphere at various temperatures to dope with nitrogen. The structure and morphology of the obtained samples were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated by the degradation of rhodamine B solution under visible light irradiation. TiO2/SiO2 was of core-shell structure, and the TiO2 shell was about 10 nm in thickness. The phase transition of TiO2 at high temperature was inhibited by the formation of the Ti-O-Si bond. TiO2/SiO2 was modified by N doping in the form of the Ti-O-N bond. The effects of calcination temperature on the photocatalytic activity were investigated. The highest activity was obtained with TiO2/SiO2 calcined at 600 ℃ for 1 h under ammonia atmosphere. The SiO2 core resulted in better adsorption property, and the N-doped TiO2 shell resulted in visible light sensitization. N-doped TiO2/SiO2 benefited from both of the effects.

Key words: nitrogen doping, visible light, titania, silica, core-shell structure, photocatalysis