A very simple method for the preparation of Au/TiO2 plasmonic photocatalysts working under irradiation of visible light in the range of 600-700 nm.

By using a facile calcination method, we succeeded in the preparation of partially spherical gold particles supported on TiO2 exhibiting photoabsorption due to surface plasmon resonance at around 620 nm. Surprisingly, the selective oxidation of benzyl alcohol to benzaldehyde occurred in an aqueous suspension of thus-prepared Au/TiO2 under irradiation of light from a Xe lamp with an R60 cut-off filter (λ > 600 nm), and the apparent quantum efficiency reached 7.2% at 625 nm and 4.2% even at 700 nm.