Stable monodisperse colloidal spherical gold nanoparticles formed by an imidazolium gemini surfactant-based water-in-oil microemulsion with excellent catalytic performance

摘要

A facile and versatile method for the synthesis of stable monodisperse colloidal gold nanoparticles was developed using a water-in-oil microemulsion-templating strategy. The water-in-oil microemulsion was composed of cationic imidazolium gemini surfactant [C-14-4-C(14)im]Br-2, 1-heptane, 1-pentanol and HAuCl4 aqueous solution. The properties of these Au nanoparticles have been fully characterized using transmission electron microscopy (TEM), high-resolution TEM (HR-TEM) observations, X-ray diffraction (XRD), and UV-vis measurements. It can be observed that the monodisperse gold nanoparticles possess a hexagonal close-packed mode and can further aggregate to a rotundity which is shaped like a micro emulsion template while we can not get this kind of morphology using other templates such as [C(14)min] Br, sodium 1-tetradecanesulphonate or tetradecyltrimethylammonium bromide (TTAB). Moreover, the catalytic efficiency of the gold nanoparticles was evaluated by using the reduction of 4-nitroaniline (4-NA) by potassium borohydride (KBH4) in aqueous solution and electrochemical reduction of hydrogen peroxide (H2O2). These Au nanoparticles possess excellent properties making them fascinating candidates for a variety of applications such as catalysis and life science.