Seed-mediated synthesis of gold octahedra in high purity and with well-controlled sizes and optical properties

We report a facile method for the synthesis of uniform Au octahedra with well-controlled sizes and optical properties by seed-mediated growth. Starting from single-crystal seeds of Au spheres with a uniform size, we could reproducibly obtain Au octahedra with a narrow size distribution (<7% in standard deviation) and in high purity (>90%). Moreover, the edge lengths of these Au octahedra could be readily tuned in a controllable fashion from 16 to 77 nm by varying the amount of seeds, the concentration of HAuCl(4) , or both. We have also investigated the effects of water and poly(vinyl pyrrolidone) (PVP) in the system, as well as the reaction temperature, on the evolution of octahedral shape.