Shape-Controlled Gold Nanoparticle Synthesis

Report No. ARL-TR-6662
Authors: Hailey E. Cramer; Lily Giri; Mark H. Griep; Shashi P. Karna
Date/Pages: September 2013; 24 pages
Abstract: At the nanoscale, the optical, electrical, and catalytic properties of a material depend on its size and shape. Therefore, synthesis of nanoparticles with controlled size and shape is important for their application in biosensors, photonics, and other optoelectronic devices. Whereas the effect of size on the properties of nanoparticles has been extensively studied in the past two decades, similar studies on the shape of nanoparticles have received little attention. The specific goals of this research are to synthesize nanoparticles with desired shapes and investigate their structure-property relationships. Recently, we successfully synthesized colloidal gold (Au), silver (Ag), and mixed Au–Ag nanoparticles using aqueous chemistry. The particles exhibited a mixture of shapes, including spheres, rods, and prisms. In the present work, we synthesize Au nanorods, nanospheres, and nanotriangles using a wet-chemical, seed-mediated growth method employing the surfactant cetyltrimethylammonium bromide as a growth-directing micellar template. It was possible to obtain these shapes through precise tuning of thermodynamic and kinetic parameters and the addition of small concentrations of halide and metal ions. Characterization of the particles was performed using tunneling electron microscopy, energy-dispersive spectroscopy, ultraviolet-visible spectroscopy, and dynamic light scattering.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2013