Sequential growth of rutile TiO₂ nanorods and anatase TiO₂ nanoparticles on TiO₂/SiO₂ template spheres

TiO₂ nanorod spheres were synthesized in a highly acidic hydrothermal solution by using TiO₂/SiO₂ spheres as template. Electron microscopy observation and X-ray diffraction analysis indicate that the dissolution of anatase TiO₂ in the template spheres leads to the growth of rutile TiO₂ nanorod on the surface of the template spheres in the initial stage of hydrothermal process and the deposition of anatase TiO₂ nanoparticles on the preformed nanorods in the later stage of hydrothermal process. Herein, SiO₂ in the template spheres assisted the loading of rutile TiO₂ nucleuses on the surface of template spheres through preventing the collapse of the template spheres in highly acidic hydrothermal solution. With the dissolution of anatase TiO₂, the template spheres gradually transformed from solid to hollow. The nanorod hollow spheres prepared by a hydrothermal period of 24 h showed high stability of physical property, excellent cycle reproducibility of photocatalytic activity, and enhanced photocatalytic activity as compared with the template spheres. - Highlights: • TiO₂ nanorod spheres are synthesized. • TiO₂/SiO₂ microspheres are used as template. • Depositions of nanorod and nanoparticle are self-controlled. • Hollow structure is obtained through dissolution-redeposition. • Phase hybrid TiO₂ nanorod spheres show high photocatalytic activity.