Single-Particle Spectroelectrochemistry: Electrochemical Approaches for Tuning Chemical Interfaces and Plasmon Damping in Single Gold Nanorods

Abstract

The strong adsorption of thiol molecules on gold nanorods (AuNRs) results in localized surface plasmon resonance (LSPR) energy loss via chemical interface damping (CID). This study investigated the CID effect induced by thiophenol (TP) adsorption on single AuNRs and the in situ tuning of LSPR properties and chemical interfaces through electrochemical potential manipulation. The potential-dependent LSPR spectrum of bare AuNRs exhibited redshifts and line width broadening owing to the characteristics of capacitive charging, Au oxidation, and oxidation dissolution. However, TP passivation provided stability to the AuNRs from oxidation in an electrochemical environment. Electrochemical potentials induced electron donation and withdrawal, causing changes in the Fermi level of AuNRs at the Au–TP interface, thereby controlling the LSPR spectrum. Additionally, the desorption of TP molecules from the Au surface was electrochemically achieved at the anodic potentials further away from the capacitive charging region, which can be used to tune chemical interfaces and the CID process in single AuNRs.