Seed-Mediated Synthesis of Gold Octahedra in High Purity and with Well-Controlled Sizes and Optical Properties

Abstract

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.