Synthesis and Characterization of Titania Nanotubes with Au Nanoparticles

TiO2 nanotubes were prepared by hydrothermal synthesis and modified with different amounts of gold nanoparticles by deposition-precipitation with urea. The catalysts were characterized to determine the effect of the presence of Au nanoparticles on the physico-chemical characteristics of the materials and their electron storage capability. Raman spectroscopy revealed the transformation of the trititanate structure into the titania anatase domains upon gold deposition. This transformation was enhanced by an increase in Au loading and the thermal treatment of the materials. The size of Au nanoparticles increased upon the reduction treatment. The presence of Au nanoparticles produced a slight narrowing of the energy bandgap of the titania nanotubular material and had an important effect on its photoluminescence properties, important for some practical applications. Photoluminescence spectroscopy showed that the presence of Au nanoparticles on the surface of titania nanotubes significantly delayed electron-hole recombination and increased the ability of materials for charge separation. Superior performance of Au-containing titania nanotubes was illustrated by the evaluation of their photocatalytic activity. Au-containing titania nanotubes showed enhanced photocatalytic activity in the degradation of methylene blue dye in aqueous solutions upon UV irradiation compared to the pristine nanotubes and the titania Degussa P25.