Abstract: Solid precursory microspheres composed of Ti/Si species were in situ formed on the surface of a colloid carbon microsphere template derived from glucose polymerization and carbonization by a one-pot hydrothermal method using ammonium fluorotitanate, ammonium fluorosilicate, and glucose as source materials. Si-doped TiO₂ hollow microspheres were then obtained after calcination and removal of the carbon microsphere template at high temperature. High-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and N₂ adsorption-desorption were used to characterize the samples. The effect of Si doping on the microstructure and photocatalytic performance of the TiO₂ hollow microspheres was investigated. The results confirmed that the Si element entered into the lattice of TiO₂ and formed Si–O–Ti bond, which could not only effectively suppress the phase transformation from anatase to rutile, but also restrain the rapid growth of TiO₂ nanocrystallites during the calcination process. The average grain size of the nanocrystallites constituting the shell of the microspheres decreased gradually and the specific surface area and pore volume of the hollow microspheres increased progressively with the increase in the amount of Si doping. The photocatalytic activity of the Si-doped TiO₂ hollow microspheres was measured under ultraviolet light using methylene blue solution as a simulated degradation model. The results demonstrated that the degradation efficiency of TiO₂ hollow microspheres enhanced gradually with increasing Si doping in its mol fraction range of 0–0.5. Especially, the degradation efficiency of TiO₂ hollow microspheres is 1.25 times that of P25 when the Si mol fraction is 0.5.

Key words: silicon doping, titania, carbon microsphere template, hydrothermal synthesis, hollow microsphere, photocatalysis