Harvesting hot electrons on Au nanoparticle monolayer by efficient compensation of holes

Abstract Plasmonic metal nanoparticles (NPs), due to its unique optical properties, has been employed in various fields, including photocatalysis and surface-enhanced Raman scattering (SERS). Hot electrons generated from non-radiative decay of plasmons can be transferred to reactant molecules adsorbed on the metal surface and thus greatly facilitate photocatalytic chemical conversions under far milder conditions than conventional thermal catalysis. However, due to the ultra-fast relaxation or recombination, the number of hot electrons that can be effectively utilized is very limited. Herein, we report the efficient compensation of holes and harvesting hot electrons by adding NaBH4 or acidic Na2SO3 solution as holes scavenger to contribute for the lasting generation of hot electrons as well as active hydrogen species. A six-electron photocatalytic reduction of nitroarenes is achieved under laser illumination even on the catalytically inert ∼80 nm Au NP self-assembled monolayer (SAM) after NaBH4 or acidic Na2SO3 solution are added. The role of NaBH4 or acidic Na2SO3 solution is elucidated to compensate holes rather than directly reduce the nitroarene. This concept of harvesting hot electrons by quick compensation of holes offers new opportunities for driving efficient light-to-energy conversion.