Mesoporous titanium dioxide coating on gold modified silica nanotubes: A tube-in-tube titanium nanostructure for visible-light photocatalysts

A novel tube-in-tube structured titanium dioxide (TiO₂) based visible-light photocatalyst with non-metal doping and plasmonic metal decoration was fabricated using a well-controlled programmed synthesis method and was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), N₂ adsorption/desorption, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy. The as-obtained tube-in-tube structure is composed of inner mesoporous silica nanotubes with high specific surface area and an outer layer of anatase TiO₂ nanocrystals with considerable visible-light activity. For the photocatalytic degradation of rhodamine B (RhB) in aqueous solution, the photocatalyst showed superior photocatalytic activities compared with commercial TiO₂ and nanometer-sized photocatalyst Degussa P25. The strategy is simple, but efficient, and can be extended to the synthesis of other multifunctional composites. It has opened a new pathway for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest.