Plasmon-Enhanced Photoluminescence and Photocatalysis Reactions in Metal-Semiconductor Nanomaterials: UV-Generated Hot Electron in Gold-Zinc Oxide

Herein, we introduce a mechanistic study to design a hybrid junction in metallic-semiconductor (M/SC) nanostructures. UV-light-induced hot electron generation in ZnO nanostructures is used to precisely tune the photoluminescence (PL) and photocatalytic (PC) properties in hybrid Au/ZnO nanomaterials. Both enhancement and quenching of the PL and PC functionalities are observed, depending on the properties of the Au nanoparticles (AuNPs) and the Au/ZnO molecular distance. Under UV irradiation free-ligand AuNPs quench the luminescence of ZnONPs through direct charge transfer (CT) from ZnO to the AuNPs. In contrast, capped AuNPs enhance the ZnO emission through indirect CT from AuNPs to ZnONPs facilitated by the distance created by the CTAB ligand between both constituents of the hybrid systems. It is necessary to optimise the Au/ZnO molecular distance to achieve an enhancement of both the plasmonic photocatalysis reaction and photoelectric properties of M/SC nanostructures. This phenomena is mediated by the energy transfer (ET) from ZnONPs to AuNPs. The resulting PL enhancement is described by the plasmon-induced resonance energy transfer effect (PIRET effect).