Synthesis, structure evolution, and optical properties of gold nanobones

Anisotropic nanoparticles, such as rods or bones, exhibit new properties due to their specific geometries. The development of unique properties on the surface of gold nanorods, such as sharp corners or edges that form gold nanobones, adds more catalytic and optical characteristics. However, because of the difficulty and lack of good facet control of the gold nanorods’ surface, the achievement of high precision of the transformation from gold nanorods to gold nanobones remains challenging. Herein, we developed a method for the growth of {200} facets of single crystalline gold nanorods to form gold nanobones using an anionic aromatic additive, 5-bromosalicylic acid, as a co-factor that will lead the evolution of the gold nanorods’ geometry throughout their overgrowth. An increase in the amount of 5-bromosalicylic acid plays a key role in the development of uniform and high yield bone shape. Several high-index facets appear at the corners during the transformation of gold nanorods to gold nanobones. The synthesized gold nanobones exhibit different mechanisms of assembly in water as well as unique optical properties compared to gold nanorods, which display a high extinction coefficient. In conclusion, we developed a new growth technique using 5-bromosalicylic acid to produce a high-yield of highly uniform gold nanobones. Studying their structural evolution and optical properties could be a useful tool for many catalytic and optical applications. Graphic abstract Scheme of the synthesis of gold nanobones using 5-bromosalicylic acid.