Growth Mechanism of Gold Nanorods

Abstract

Gold nanorods (Au NRs) are the archetype of a nanoantenna, enabling the directional capture, routing, and concentration of electromagnetic fields at the nanoscale. Solution-based synthesis methods afford advantages relative to top-down fabrication but are challenged by insufficient precision of structure, presence of byproducts, limited tunability of architecture, and device integration. This is due in part to an inadequate understanding of the early stages of Au NR growth. Here, using phase transfer via ligand exchange with mono-thiolated polystyrene, we experimentally demonstrate the complete evolution of seed-mediated Au NR growth in hexadecyltrimethylammonium bromide (CTAB) solution. Au NR size and shape progress from slender spherocylinders at short reaction times to rods with a dumbbell profile, flattened end facets, and octagonal prismatic structures at later stages. These evolve from a single mechanism and reflect the majority of reported Au NR morphologies, albeit reflecting different stages. Add...