Synthesis of stable dispersion of copper nanoparticles in a water-in-supercritical carbon dioxide using polydimethylsiloxane as the stabiliser

摘要

This study reportes the synthesis of stable dispersion copper nanoparticles by chemical reduction of copper chloride (CuCl_2) in a water-in-supercritical carbon dioxide medium using sodium borohydrate (NaBH_4) as a reducing agent, polydimethylsiloxane as the stabiliser and sodium bis(2-ethylhexyl)sulphosuccinate (AOT) as co-surfactant at temperature 40_C and pressure in the range 2000-2400 psi. UV-visible spectroscopy exhibits a typical emission peak at 560-590nm for Cu nanoparticles. By changing the reaction pressure and the stabiliser concentration, the size and the shape of the copper nanoparticles could be easily controlled. The X-ray diffraction pattern reveals that the Cu nanoparticles are formed in the range 4-8 nm, which is consistent with the transmission electron microscopy images.