Size Effect on Formic Acid Dehydrogenation over Plasmonic Au@Pd Core–Satellite Nanostructures

Plasmon-derived photocatalysis intimately depends on the optical properties of plasmonic nanoparticles (NPs), which are strongly sensitive to the size of the particles. Herein, we chose the plasmonic Au@Pd core–satellite NPs to investigate their size effect on the photocatalytic formic acid (FA) dehydrogenation under visible light irradiation. We synthesized various hybrid Au@Pd NPs with a spherical Au core spanning a wide size range to delicately tune the scattering/absorption ratio of the plasmonic NPs. The relative contribution of scattering to extinction significantly increased by increasing the Au core size from 50 to 120 nm. The Au@Pd NPs demonstrated a size-dependent catalytic activity, and the smallest Au@Pd NPs with the highest absorption/extinction ratio possessed the best catalytic performance. More impressively, the high-scattering large Au@Pd NPs exhibited unexpectedly enhanced activities by moderately raising the reaction temperature or shortening the interparticle distance, which was caused by an improved photon utilization through multiple absorptions of scattered light as a consequence of increased photon path length. The insights gained from this work shed light on the underlying role of particle size-correlated scattering on the plasmon-enhanced catalysis for FA dehydrogenation.