Silica coating of copper nanoparticles by a fast and facile microwave method

Abstract

A rapid process of silica coating of colloidal copper nanoparticles by microwave method was studied. Copper nanoparticles were prepared from CuCl 2 aqueous solution using hydrazine as reducing agent and cetyltrimethyl ammonium bromide and citric acid as stabilizers. Obtained copper nanoparticles having the mean diameter of around 30 nm were surface-treated by 3-aminopropyltriethoxysilane and then surface-coated with silica using tetraethoxysilane or silanol terminated polydimethylsiloxane as silica precursors. The uncoated and silica coated copper nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction measurements. By varying several conditions, Cu nanoparticles could be coated with uniform silica shell with the reaction time, i.e. the microwave irradiation time, of only 5 min, although single core containing core-shell nanoparticels could not be obtained. Conclusively, this microwave method is one of the green processes for its short reaction time.