Synthesis of gold nanoparticles dispersed within pores of mesoporous silica induced by ultrasonic irradiation and its characterization

Gold (Au) nanoparticles loaded within pores of mesoporous silica were in situ synthesized by sonochemical reduction of chloroauric acid (HAuCl4) within pores of silica. The sonochemical reduction was carried out by ultrasonic irradiation in argon atmosphere at room temperature. The composite was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HREM) techniques. It has been shown that nearly spherical shaped Au nanoparticles, with a fairly narrow size distribution, are isolated from each other and uniformly dispersed within the pores, which are less than 9 nm in diameter. With the decrease of particles size, a significant red-shift of surface plasma resonance (SPR) band of Au particles was observed in the optical absorption measurement.