Deposition of Gold Nanoparticles on Silica Spheres:  A Sonochemical Approach

Abstract

Gold nanoparticles with an average size of ∼5 nm were deposited on the surface of preformed silica submicrospheres with the aid of power ultrasound. The sonochemical reduction was carried out by ultrasonic irradiation in an argon atmosphere at room temperature. Ultrasonic irradiation of a slurry of silica submicrospheres, chloroauric acid (HAuCl4), and ammonia in an aqueous medium for 45 min yielded a gold−silica nanocomposite. By controlling reaction conditions, we could achieve the deposition of metallic gold on the surface of the silica spheres. A unique crystallization process of the silica particles is observed. The crystallization process is assisted by the gold nanoparticles yielding the cristobalite phase of silica at a relatively low temperature. The resulting gold-deposited silica submicrosphere samples were characterized with XRD, EDAX, TEM, TGA, DSC, HR-SEM, and FT-IR, photoacoustic, and UV−visible spectroscopy.

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

“…It is highly likely that copper nanocrystallites act as nucleation sites accelerating silica's transition from the amorphous to crystalline phase during the calcination process. This is in agreement with previous studies in which the addition of a small amount of metal ions affected silica's crystallization kinetics [32,33]. Moreover, in the 7.7 wt % copper loaded silica material, trace peaks possibly corresponding to tenorite (JCPDS # 3-884) and copper phosphate (JCPDS # 44-182) phases could also be detected.…”

Titania–silver and alumina–silver composite nanoparticles: Novel, versatile synthesis, reaction mechanism and potential antimicrobial application

“…All reagents were > 99 % purity and were used as received. 2 or Al 2 O 3 powder was stirred with 10 ml of 1X10 -2 M oleic acid in methanol at 500 rpm on a magnetic stirrer at room temperature until evaporation. 10 ml of 1X10 -2 M aqueous AgNO 3 solution, sufficient to yield a final loading of silver nanoparticles of 1 wt% (calculated with respect to the initial mass of oxide), was added to the dried sample.…”

“…Numerous reports describe the synthesis of such composite materials, with particular emphasis on immobilization of noble metal nanoparticles on oxides such as SiO 2 [1][2][3], TiO 2 [4][5][6][7][8][9][10] and Al 2 O 3 [11][12][13][14][15][16]. These oxides are of interest due to their ready availability, ease of handling, low toxicity and low cost.…”

Applications of nanomaterials in liquid chromatography: Opportunities for separation with high efficiency and selectivity

“…Previous studies have also demonstrated their potential applications in LC as mentioned above. Recently, synthesis of nanometer-sized core-shell structures consisting of silica core and precious metal shell (e. g., Au, Pt, Ag) as well as precious metal core and silica shell has become an increasingly important topic [53][54][55][56][57][58][59][60][61]. The precious metal nanoparticles are of several nanometers in diameter in the resulting core-shell composites of several hundred nanometers in size.…”