Gold Nanoparticles Located at the Interface of Anatase/Rutile TiO₂ Particles as Active Plasmonic Photocatalysts for Aerobic Oxidation

Visible-light irradiation (λ > 450 nm) of gold nanoparticles loaded on a mixture of anatase/rutile TiO₂ particles (Degussa, P25) promotes efficient aerobic oxidation at room temperature. The photocatalytic activity critically depends on the catalyst architecture: Au particles with <5 nm diameter located at the interface of anatase/rutile TiO₂ particles behave as the active sites for reaction. This photocatalysis is promoted via plasmon activation of the Au particles by visible light followed by consecutive electron transfer in the Au/rutile/anatase contact site. The activated Au particles transfer their conduction electrons to rutile and then to adjacent anatase TiO₂. This catalyzes the oxidation of substrates by the positively charged Au particles along with reduction of O₂ by the conduction band electrons on the surface of anatase TiO₂. This plasmonic photocatalysis is successfully promoted by sunlight exposure and enables efficient and selective aerobic oxidation of alcohols at ambient temperature.