Synthesis of Copper Nanoparticles in Aqueous Ambient Using Dismutation Reaction Khodarahm Ghandi and Yousef Zeraatkish* 1 Department of physiscs, Behbahan Branch, Islamic Azad University, Behbahan, Iran The present study has investigated the synthesis of copper nanoparticles via copper dismutation reaction in an aqueous solution and ambient conditions. Copper (II) chloride hydrate (     ), sodium oleate (SO), sodium chloride (NaCl) and ethylene diamine (EN) have been used as copper (I, II) ions source, surfactant, chloride ions supplier and ligand, respectively. Also, an amount of hydrochloric acid (HCl) was used as a multiplier for reaction rate. To perform copper dismutation reaction in the aqueous solution, the copper (I)–chloride complexes were first prepared from       at a high concentration of chloride solution. Then, sodium oleate was added to solution as a size modifier. The reaction proceeded through the addition of ethylenediamine as a ligand to the solution. The crystalline structure, size, and morphology of the copper nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) techniques, respectively. According to the analyses, the synthesized particles are less than 20 nanometers in size and spherical in shape. Keywords: Dismutation; Comproportionation; TEM; SEM; Copper nanoparticles © 2014 Published by Journal of NanoAnalysis. 1. Introduction Reports on the various methods for synthesis of nanoparticles have shown the growing importance attached to the synthesis of metal nanoparticles in the recent literature. Metal nanoparticles have numerous industrial and scientific applications and are used for qualifying materials and instrument properties, improving human health etc. In this context, copper nanoparticles are commonly applied and many researchers have stressed the emphasis of copper nanoparticles properties, applications and synthesis. Previous studies on the thermal conductivity and viscosity of copper nanoparticles in fluids have shown an increase in the aforementioned properties versus the normal fluids. The measurements of some Cu suspensions indicate that the nanoparticle diameter, volume fraction, and bulk temperature have a considerable impact on the effective thermal conductivity of these nanofluids (1, 2). It has been reported that copper nanoparticles show good catalytic activity both as homogeneous and heterogeneous catalytic hydroxylation of phenol by hydrogen peroxide to dihydroxybenzenes (3-5). Copper nanopaste and atmospheric-pressure plasma (APP) sintering is highly adoptable for mass production of printable and flexible electronic devices at low cost. The Cu patterns sintered at 250 W for 40 min showed the lowest electrical resistivity of 21.06 μΩ cm, which is around 12.61 times less than the bulk Cu (6). Copper nanoparticles show also antimicrobial activity. In this case, the starch-stabilized copper nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micro molar concentrations (7). The copper nanoparticles have lethal effects against Escherichia coli, B. subtilis and S. aureus microorganism (8, 9). Moreover, Copper nanoparticles are promising for application in cancer cell battling (10). Laser ablation, a physical process, is used to synthesize metal (copper and so on) nanoparticles in arbitrary fluids directly (11). Another synthesis method is wire explosion. In this method a thin copper wire is exploded by passing high current through it. In wire explosion technique, average diameter of particles depends on the applied pressure (12). The synthesis of copper nanoparticles using reverse micelles in organic solvents has also been reported. Sodium bis(2-ethylhexyl)sulfosuccinate (AOT), for instance, is an important process to create reverse micelle in this * Corresponding author. Tel.: +982123064350 E-mail address:Yousefkish2@gmail.com