High yield shape control of monodispersed Au nanostructures with 3D self-assembly ordering

High purity Au nanoparticles and nanorods have been synthesized using seed-mediated approach in aqueous solution with the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The control of seed concentration and the addition of silver nitrate yield Au nanostructures of high monodispersivity. After obtaining high concentration dispersion of anisotropic monodispersed colloidal nanocrystals, evaporation induced self-assembly of Au nanostructures was carried out. The Au nanocrystals experience strong capillary forces through the surface of the drying solvent which forces them to self-assemble while CTAB assist in drawing the nanocrystals closer without aggregating them and finally homogeneity in the shapes and sizes of the as-synthesized Au nanocrystals facilitate the self-assembly of Au nanostructures into ordered 3D assemblies. Thus, in the preparation of a large-scale assembly, high concentration, surfactant capping and monodispersivity of the Au nanostructures are essential.