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

Abstract

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 Au₃(DP₃₅₀)/TiO₂ with a loading of 3 wt% Au NPs and calcining at 350 °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 Au₃(DP₃₅₀)/TiO₂ sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au₃(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.