Plasmonic photocatalysis properties of Au nanoparticles precipitated anatase/rutile mixed TiO2 nanotubes

Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au-3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 degrees C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au-3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au-3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail.