Gold-core lithium-doped titania shell nanostructures for plasmon-enhanced visible light harvesting with photocatalytic activity

A simple sol-gel synthesis method has been developed to synthesize uniform nanospheres of gold lithium-doped titanium dioxide in anatase phase (Au/Li-TiO₂) with a well-defined core-shell structure with the Li-doped titania as shell and Au nanoparticles as core. The resulting core-shell nanoparticles have a high surface area (~494 m²/g) and uniform pore size (~3.5 nm) for the anatase shell. The synthesis of the gold nanoparticles refers to the classical Turkevich synthesis, and the diameter can be regulated by adjusting the amount of HAuCl₄. The gold nanoparticles were first covered with citrate group and subsequently removed by thermal treatment. The catalytic performance of Au/Li-TiO₂ was investigated using the degradation of rhodamine B in water for a model reaction using UVb and visible light. The high surface area of the anatase shells provides direct access for the reactant molecules to diffuse and subsequently interact with the gold cores.