Synthesis and characterization of hierarchical TiO2 microspheres composed of nanorods: effect of reaction conditions on nanorod density

Urchin-like hierarchical TiO2 microspheres consisting of numerous nanorods were successfully synthesized by a facile hydrothermal process. The effects of reaction conditions ( such as additives and reactant concentrations) on TiO2 morphology, particularly on rod density, were systematically investigated. The relationship between rod density and rod diameter was discussed. Based on the above results including a morphological evolution study, a possible mechanism was also proposed to elucidate the growth process of hierarchical TiO2 microspheres using nanorods as building units.