Simultaneous formation of silica-protected and N-doped TiO 2 hollow spheres using organic–inorganic silica as self-removed templates

Synthesis of N-doped TiO 2 hollow spheres with a small grain size, large surface area and high degree of crystallinity is favorable to achieve an overall high photocatalytic activity. But traditional synthetic approaches generally involve many tedious steps and are time-consuming. Here we present a facile method to synthesize N-doped TiO 2 hollow spheres using organic silane-doped silica nanoparticles as templates. The organic–inorganic silica can be simultaneously etched during the deposition of TiO 2 shell to create a thin silica layer on the TiO 2 surface. Such a thin silica layer can efficiently protect the TiO 2 nanocrystals from growing larger during high-temperature calcination. At the same time, the organic silane can serve as a nitrogen source to be doped in the TiO 2 shell. The developed silica-protected and N-doped TiO 2 hollow spheres can be directly employed as photocatalysts without SiO 2 etching and show obvious light utilization in both UV and visible bands.