Synthesis and optical behavior of copper nanoparticles in different media

In this report, we describe a simple and rapid chemical reduction method with inert gas protection, for preparing stable copper nanoparticle with average particle size of 9.4 nm. In our synthesis route, ascorbic acid is used as antioxidant to effectively prevent the general oxidation process during copper nuclei formation. As-prepared copper nanoparticles were transferred from water phase to different organic solvents (hexane, octane, cyclohexane, and toluene) using oleylamine as a phase transfer agent. This should allow dispersion of the particles in both polar and nonpolar solvents and avoid particle aggregation during the solvent exchange process. Transmission electron microscopy and UV–Vis spectroscopy contributed to the analysis of size and optical properties of the copper nanoparticles in different media, respectively. The advantages of such solvent exchange process can be found in the applications of metal particles as catalysts for organic reactions in nonpolar solvents and in the study of the changes in surface chemistry depending on the surrounding medium and on the adsorption of different moieties