Hard-template synthesis of titanium dioxide hollow spheres

An easy approach for the fabrication of titanium dioxide hollow spheres is proposed. Nanostructures were obtained by the conventional hard template method with silica-protected calcination. The samples were characterised by differential thermal analysis and thermogravimetry, Brunauer-Emmett-Teller nitrogen adsorption isotherms, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM). Raman spectroscopy and optical properties of the prepared materials were studied as well. X-ray analysis has shown that the silica protection layer allows direct phase transformation from amorphous titania to crystalline anatase regardless of the temperature. The crystallite size is more than 5 nm. The diameter of the obtained hollow nanostructures is within the range 115-420 nm. The thickness of the walls varies from 12 to 38 nm depending on annealing conditions. TEM and SEM images confirm their spherical shape.