Rapid and fine tailoring longitudinal surface plasmon resonances of gold nanorods by end-selective oxidation

Abstract Facile achievement of gold nanorods (AuNRs) with controllable longitudinal surface plasmon resonance (LSPR) is of great importance for their applications in various fields. The LSPR of AuNRs is sensitive to their aspect ratio, which is still hard to be precisely tuned by direct synthesis. In this work, we report a simple approach for end-selective etching of AuNRs by a rapid oxidation process with Au(III) in cetyltrimethylammonium bromide (CTAB) solution at a mild temperature. The LSPR wavelength and the length of AuNRs blue shifted linearly as a function of the amount of Au(III), while the diameter of AuNRs remained nearly constant. The oxidative rate is temperature dependent, and the oxidative process for a desired LSPR can be accomplished within 15 min at 60 °C. Further investigations indicated that Br– determine the occurrence of the oxidation between AuNRs and Au(III), and a small amount of surfactant chain (CTA+) is crucial for stabilizing AuNRs. This method presents a quick but robust strategy for acquiring AuNRs with an arbitrary intermediate LSPR wavelength using the same starting AuNRs, and can be a powerful tool for subsequent applications.