Enhancement of light-matter interaction and photocatalytic efficiency of Au/TiO₂ hybrid nanowires.

Metal/TiO₂ hybrid nanostructures offer more efficient charge separation and a broader range of working wavelengths for photocatalytic reactions. The sizes and shapes of such hybrid nanostructures can affect the charge separation performance when the structures interact with light, but assessments of the interaction of light with these metal-TiO₂ nanostructures have only been carried out on ensemble averages, hindering both systematic descriptions of such hybrid structures and the design of new ones. Here, we fabricated TiO₂ nanotubes (NTs) with and without core Au nanowires (NWs), and used spectroscopy and calculations to assess their scattering and absorption of light at the single NW level. According to the results of spectral imaging and numerical calculations, the Au/TiO₂ NWs scattered and absorbed light substantially more strongly than did the plain TiO₂ NTs. Measurements of the degradation of the AO7 dye to assess the photocatalytic performance of the Au/TiO₂ NWs were consistent with optical measurements demonstrating a two-fold improvement over plain TiO₂ NTs under 360-nm-wavelength UV illumination. Our results suggests that nanoscale optical imaging can be used to visualize the performance of the photocatalytic reaction at the single nano-object level.