Fabrication of Ag-modified hollow titania spheres via controlled silver diffusion in Ag–TiO2 core–shell nanostructures

Inorganic hollow spheres find a growing number of applications in many fields, including catalysis and solar cells. Hence, a simple fabrication method with a low number of simple steps is desired, which would allow for good control over the structural features and physicochemical properties of titania hollow spheres modified with noble metal nanoparticles. A simple method employing sol–gel coating of nanoparticles with titania followed by controlled silver diffusion was developed and applied for the synthesis of Ag-modified hollow TiO2 spheres. The morphology of the synthesized structures and their chemical composition was investigated using SEM and X-ray photoelectron spectroscopy, respectively. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag–TiO2 hollow nanostructures with different optical properties were prepared simply by a change of the annealing time in the last fabrication step. The synthesized nanostructures exhibit a broadband optical absorption in the UV–vis range.