Preparation of nitrogen-doped TiO2/SiO2 microspheres with core-shell structure and their photocatalytic activity under visible light

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 coreshell 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 degrees C 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.