Plasmon-Induced Electron Transfer between Gold Nanorods and a Carbon Thin Film

Plasmonic nanostructures have been demonstrated as emergent photocatalysts because of their efficient photon absorption and their ability to produce hot carriers. However, the plasmon-generated hot carriers decay through ultrafast relaxation pathways, resulting in a short lifetime that impedes the exploitation of hot carriers for chemical reactions. Charge separation at the heterojunction of the hybrid nanostructures can counteract the ultrafast decay to extend the carrier lifetime. Here, we fabricate hybrid nanostructures composed of gold nanorods and a carbon thin film and demonstrate efficient charge transfer between these two materials. Using single-particle dark-field scattering spectroscopy, we observe a broadening of the longitudinal plasmon for gold nanorods on a carbon film compared to those on a glass substrate. We attribute this plasmon damping to the electron transfer from gold nanorods to the carbon film and exclude the contribution from plasmon-induced resonance energy transfer. The electron transfer efficiencies are calculated as 52.8 ± 4.8 and 57.4 ± 4.0% for carbon films with thicknesses of 10 and 25 nm, respectively. This work demonstrates efficient charge separation at the gold–carbon film interface, which can extend the lifetime of hot carriers to promote plasmonic photocatalysts.