Gold and gold–palladium alloy nanoparticles on heterostructured TiO2 nanobelts as plasmonic photocatalysts for benzyl alcohol oxidation

Abstract

Plasmonic photocatalysts composed of Au and bimetallic Au–Pd alloy nanoparticles (NPs) on one-dimensional TiO₂ nanobelts (TiO₂-NBs) were used for the aerobic oxidation of benzyl alcohol under visible light irradiation. Remarkable light-promoted activity was observed for the as-synthesized M/TiO₂-NB (M = Au, Au–Pd) nanostructures based on the TiO₂(B)/anatase heterostructured nanobelt. The difference in band structure and the well matched interface between the TiO₂(B) and anatase phases, coupled with the one-dimensional nanostructure, enable an enhanced charge transfer within the heterostructured nanobelt. This inter-phase charge transfer greatly facilitates the flow of hot electrons from the metal NPs to TiO₂ and promotes benzyl alcohol oxidation. This efficient electron transfer was identified by the much higher photocurrent response measured for the Au/TiO₂-NB nanostructure with the TiO₂(B)/anatase heterojunction than those with either of the single phases under visible light irradiation. Alloying Au with Pd in Au–Pd/TiO₂-NB results in a significant improvement in the visible light-promoted activity compared to the monometallic Au/TiO₂-NB sample. It is supposed that the plasmon-mediated charge distribution within the alloy NPs is mainly responsible for the enhanced photocatalytic activity of the bimetallic nanostructures.