Synthesis of submicrometer-sized hollow titania spheres with controllable shells

Submicrometer-sized hollow titania spheres with controllable shells have been prepared using polystyrene particles as a template in conjunction with the sol-gel method. The hollow spherical structures could be confirmed by transmission electron microscope (TEM) and scanning electron microscope (SEM). The void sizes of the hollow spheres were 15-20% smaller than the diameters of the polystyrene template. The shell thickness and surface roughness of the hollow titania spheres increased with increasing the concentrations of titanium tetrabutoxide ethanol solutions. Furthermore, when the volume ratio of titanium tetrabutoxide to ethanol was 1:5, a porous titania structure was yielded, rather than dispersive hollow titania spheres. As expected, the shell thickness of the hollow titania spheres could be readily controlled by altering the number of the titanium tetrabutoxide layers coated on the polystyrene template. (C) 2004 Elsevier B.V. All rights reserved.