Well-organized 3D urchin-like hierarchical TiO₂ microspheres with high photocatalytic activity

This article reported a well-organized 3D urchin-like hierarchical TiO₂ which was synthesized by a simple solvothermal method without using any template or surfactant. The results of scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction showed that the hierarchical morphology and size of TiO₂ could be effectively controlled by adjusting the precursor ratio of tetrabutyl titanate to TiCl₄ solution, the concentration of TiCl₄ solution, the solvothermal temperature, and the reaction time. It is believed that the formation of the urchin-like hierarchical TiO₂ followed a ‘nucleation–self-assembly–dissolution-recrystallization’ growth mechanism. In addition, the excellent photocatalytic activity of the urchin-like hierarchical TiO₂ was confirmed by photodegradation of methyl blue in water.