Preparation and characterization of titania/ZnS core-shell nanotubes.

Core-shell nanocomposites of titania nanotubes/ZnS quantum dots have been prepared by using a hydrothermal synthetic method and characterized by using various microscopic and spectroscopic methods. ZnS quantum dots surround the outsides of titania nanotubes having the inner and the outer diameters of 15 and 30 nm, respectively, with a thickness of 2 nm. The nanocomposites suspended in water show a broader absorption spectrum shifted to a longer wavelength by 20 nm and emit substantially stronger ZnS luminescence having significantly slower decay kinetics than bare ZnS nanoparticles in water. The support of TiO2 nanotubes is found to enhance the optical properties of ZnS considerably.