Shape-controlled growth of micrometer-sized gold crystals by a slow reduction method

A method for the synthesis of micrometer-sized gold crystals with shapes ranging from three-dimensional (3D) triangles, octahedra, and pentagonal decahedra to two-dimensional (2D) plates and one-dimensional nanowire is described. These morphologies are obtained by controlling the relative growth rates of the crystal planes by the selective use of capping ligand mixtures. The size transition and shape evolution of the crystals are monitored by electron microscopy, X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Micrometer-sized crystals with different feature shapes and sizes can be obtained by changing the composition of amine ligand mixture. The shape of the particles is determined by the relative growth rates on particular cryatallographic planes during the growth process. Several procedures exists for the preparation of 1D nanostructures such as rods and wires which includes electrochemical intemplates, photochemical synthesis and seedmediated growth.