Transverse axis morphological control for tailored gold nanorod (GNR) synthesis

Abstract

Over the past decade, the quest to engineer gold nanorods (GNRs) with tailorable optical properties has intensified. Modifications to the shape and size have led to unprecedented control over the optical and localized properties of gold nanomaterials. Extensive research has demonstrated GNRs of various aspect ratio can be achieved through slight chemical modifications of the fabrication procedure. However, many of these methods suffer from poor batch-to-batch reproducibility and low overall yield. Additionally, localizing the growth to one axis has proven difficult as growth occurs from all sides in a typical seed-mediated synthesis procedure, which is a critical step for fine-tuned control. In this contribution, we demonstrate a reproducible methodology to specifically and systematically tailor the GNR transverse axis, which corresponds to the GNR radial width, to control plasmonic properties over the 550–850 nm spectral region. A remarkably high reproducibility is obtained allowing for the prediction of the optical absorption within ±12 nm. Derived from the combination of two high yield GNR wet chemical synthesis methods, herein we alter the reducing agent and gold concentration during synthesis demonstrating precise control over the transverse axis morphology and subsequent plasmonic resonance peaks.