Gold nanoparticles prepared by sonochemical method in thiol-functionalized ionic liquid

A convenient sonochemical method in preparation of gold nanoparticles capped by thiol-functionalized ionic liquid (TFIL) using hydrogen peroxide as a reducing agent was described in this paper. The obtained gold nanoparticles (GNPs) were characterized by ultraviolet–visible (UV–vis) absorption spectra, transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectra. It is found that the molar ratio of gold atom in chloroauric acid to thiol group in TFIL (Au/S) has great effects on the particles size and distribution of GNPs. The FT-IR spectra reveal that the function of thiol-containing ionic liquids is to form the bond of S–Au for stabilization of the gold cluster. Small gold nanoparticles size of 2.7 ± 0.3 nm with narrow uniform distributions can be obtained at the molar ratio of Au/S = 1:2 under ultrasound irradiation for 12 h. The reported method, which is performed in ionic liquid and hydrogen peroxide solution under ultrasound irradiation, is friendly to environment.