Branched Au Nanoparticles as Light‐Harvesting Antennae for Photosensitized Reactions

Abstract Branched Au nanoparticles (NPs) were developed as nanoantennae that can enhance photoelectrochemical reaction rates. The branched Au NP generates a strong oscillating electric field (i.e., optical near field) under light of various polarizations and incident angles. Here we prepare branched Au NPs by electrodeposition and coat them with a ZnO thin film at a relatively low temperature to improve the thermal and chemical stabilities of the NPs. The ZnO‐coated branched Au NPs are modified further with PbS NPs. The PbS‐sensitized photocurrents are enhanced even at 1300 nm by the branched Au NPs. The enhancement peak wavelength can be controlled in the 700–1300 nm range by changing the branch length.