Plasmonic Janus‐Composite Photocatalyst Comprising Au and C–TiO 2 for Enhanced Aerobic Oxidation over a Broad Visible‐Light Range

Asymmetric Janus nanostructures containing a gold nanocage (NC) and a carbon–titania hybrid nanocrystal (AuNC/(C–TiO 2 )) are prepared using a novel and facile microemulsion‐based approach that involves the assistance of ethanol. The localized surface plasmon resonance of the Au NC with a hollow interior and porous walls induce broadband visible‐light harvesting in the Janus AuNC/(C–TiO 2 ). An acetone evolution rate of 6.3 μmol h −1 g −1 is obtained when the Janus nanostructure is used for the photocatalytic aerobic oxidation of iso ‐propanol under visible light (λ = 480–910 nm); the rate is 3.2 times the value of that obtained with C–TiO 2 , and in photo‐electrochemical investigations an approximately fivefold enhancement is obtained. Moreover, when compared with the core–shell structure (AuNC@(C–TiO 2 ) and a gold–carbon–titania system where Au sphere nanoparticles act as light‐harvesting antenna, Janus AuNC/(C–TiO 2 ) exhibit superior plasmonic enhancement. Electromagnetic field simulation and electron paramagnetic resonance results suggest that the plasmon–photon coupling effect is dramatically amplified at the interface between the Au NC and C–TiO 2 , leading to enhanced generation of energetic hot electrons for photocatalysis.