Beyond the concentration limitation in the synthesis of nanobipyramids and other pentatwinned gold nanostructures.

Gold nanoparticles offer unique opto-electronic properties relevant for a wide range of processes and products, in biology and medicine (therapeutic agents, diagnostic, drug delivery), but also in electronics, photovoltaics, catalysis. So far, the various synthesis methods proposed lead to rather limited concentration and purity of the colloidal suspensions, severely hindering their use. Here, we present a simple and versatile procedure for the synthesis of gold pentatwinned nanostructures including nanobipyramids based on a seed-mediated growth process that overcomes the concentration limitations of current methods by two orders of magnitude. Moreover, our novel process offers quantitative yields, while allowing easily a fine control of the particles shape, size (with a high monodispersity), and plasmonic properties. Finally, we demonstrate that our method can be easily up-scaled to produce large amounts of nanostructures, up to the gram scale, with minimal waste and post-processing, thus, facilitating their use for further applications and industrial developments.