Size-regulated gold nanoparticles fabricated by a discharge in reverse micelle solutions

A discharge was applied to reverse micelle solutions, which provided constant volume nanoreactors, to synthesize size-regulated gold nanoparticles. The molar ratio of water to surfactant, W was varied to regulate the nanoparticle size. A pulsed power supply was used to generate the discharge in the reverse micelle Solutions. The applied voltage, pulse width, and frequency were 960 V, 2 mu s, and 15 kHz, respectively. The synthesized gold nanoparticles were observed by transmission electron microscopy (TEM). Surface plasmon absorption band of the gold nanoparticles was measured by ultraviolet-visible (UV-Vis) spectroscopy. TEM images showed that the average particle size varied from 3.8 to 11 nm in diameter as W was increased. Thus, the size of gold nanoparticles can be regulated by the volume of water droplets in the reverse micelle solutions. Reduction of [AuCl4](-) ions and formation of gold nanoparticles proceeded only inside the water droplets formed by reverse micelles. These nanoreactors regulated by reverse micelles lead to the uniform growth of gold nanoparticles. (C) 2008 Elsevier B,V. All rights reserved.