Direct Synthesis and Characterization of Gold and Other Noble Metal Nanodispersions in Sol−Gel-Derived Organically Modified Silicates

Abstract

A general approach to prepare nanodispersions of noble metals in organically modified silicates is presented with particular emphasis on the synthesis of gold nanodispersion and its characterization. Organically modified sol−gel monomers containing amine functional groups are used to stabilize the metal salts before the reduction step and to cap and prevent coagulation of the metal sol after reduction and through gel formation, drying, and aging. Uniform spherical metal nanodispersions of Au, Pt, and Pd with average diameter of 4−6 nm were obtained. The particle size distribution and the average size of silver nanoparticles prepared by the same method were considerably larger. This was attributed to the lower stability of the silver−amine complex and to the lower affinity of amines to silver surfaces. Stable aqueous colloidal solutions and supported metal nanodispersions in porous films and monoliths can be prepared by this route.

Enhanced Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl) Ruthenium(II)/tripropylamine in the Presence of Pyridine and Its Analogues

“…Further increasing its concentration, 4,4'-dipyridine began to suppress two ECL signal at the same time, as shown in Figure 5. As reported [33,34], there exit strong affinity between Au À N bond. Concentrated 4,4'-dipyridine can formed a dense monolayer on gold electrode surface which otherwise exclude electron transfer.…”

“…Previous reports [33,34] showed that there exists strong affinity between gold and nitrogen bond, as well as platinum and nitrogen bond. So it is reasonable to presume that pyridine which contains nitrogen atom in the molecule could adsorb at noble metal electrode surface as surfactant [25 -30].…”

Gold nanoparticle-based sensing platform of hydrazine, sulfite, and nitrite for food safety and environmental monitoring

“…APS-Au NPs were synthesized by a simple chemical reduction strategy (Bharathi et al 1999). In typical, total of 10 mL of sol with molar ratios of 100:0.1, 100:1, and 100:10 (3-(aminopropyl)triethoxysilane (APS)/HAuCl 4 ) were prepared by dissolving appropriate amount of APS and Au salt in methanol and 1 mL of 0.01, 0.1, and 1.0 M HAuCl 4 .…”

Green Synthesis, Cytotoxicity and Utilization of Carboxymethylchitosan-Stabilized Gold Nanoparticles.

“…Unlike most gold colloid, few amount of nonspherical particles beside most spherical one was observed. These non-spherical particles seemed to be fabricated by gathered interference of two or three spherical particles during the nucleation process [14,23]. Spectrophotometry is another important aspect for characterization of gold nanoparticles.…”