Controlled synthesis of heterogeneous metal-titania nanostructures and their applications

We describe a new synthetic approach to heterogeneous metal-TiO₂ nanomaterials based on conversion of Ti³⁺ to hydrous TiO₂ occurring uniquely on the nanostructured metallic surfaces such as Pt, Au, and Ni nanowires and nanoparticles. The TiO₂ growth mechanism was studied by designing an electrochemical cell. A variety of heterogeneous metal-TiO ₂ nanostructures, such as segmented metal-TiO₂ nanowires, core-shell metal-TiO₂ nano/microparticles, and composite metal-TiO₂ nanotubes, can be fabricated by varying the morphology of the seeding metal nanostructure or controlling selective TiO₂ growth on different surfaces of the metallic nanomaterial. Altering the reaction time and Ti³⁺ concentration allows the TiO₂ segment lengths or TiO₂ shell thicknesses to be finely tuned. Coaxial Au-TiO₂ nanorod arrays were demonstrated to be fast lithium-ion storage materials, while the core-shell Ni-TiO₂ nanoparticles exhibited excellent photodegradation properties as magnetic recyclable photocatalysts.