Encapsulation of Gold Nanoclusters in Silica Materials via an Inverse Micelle/Sol−Gel Synthesis

Abstract

Nanometer-sized gold particles were encapsulated in the micropores of xerogels and aerogels. The synthesis involves the sequential reduction of a gold salt followed by sol−gel processing in an inverse micelle solution. The inverse micelle solution solubilizes the metal salt and provides a microreactor for the nucleation, growth, and stabilization of the nanometer-sized clusters. Hydrolysis and condensation of an added siloxane precursor produces a wet gel embedding the particles. Characterization of the particle size and composition and the particle growth process was completed with transmission electron microscopy (TEM), electron diffraction, and UV−visible absorption spectrometry. Characterization of the gel surface areas was completed with N2 porosimetry. Material properties determined as a function of the gel precursor (TEOS vs a prehydrolyzed form of TEOS), the water to gel precursor reaction stoichiometry, and surfactant concentration are discussed in terms of the unique solution chemistry occurring in the microheterogeneous inverse micelle solutions.

Palladium(0) Nanoparticles on Glass‐Polymer Composite Materials as Recyclable Catalysts: A Comparison Study on their Use in Batch and Continuous Flow Processes

“…[5] Physical methods for preparation, such as the electrochemical route developed by Reetz, [6] are also numerous. [7,8] Currently, several diverse protocols for preparing nanoparticles are being pursued such as impregnation, [9] co-precipitation, [9,10] deposition/pre-cipitation, [11] sol-gel, [9,12] gas-phase organometallic deposition, [13] sonochemical, [14] micro-emulsion, [15] laser ablation, [16] electrochemical, [17] and cross-linking modalities. [18] Polymers provide stabilization for Pd(0) nanoparticles through the framework or by binding weakly to the nanoparticle surface through a heteroatom that plays the role of a ligand.…”

Surface Organometallic Chemistry on Metal: Synthesis, Characterization and Application in Catalysis

“…These include precipitation [148] , organometallic preparation and deposition [149] , sonochemical methods [150] and via microemulsions created using organic stabilizing agents [151] . Most routes mentioned include nucleation, growth and stabilization of the particles, which results in a range of particle sizes.…”

Nickel Nanoparticles Catalyzed Knoevenagel Condensation of Aromatic Aldehydes with Barbituric Acids and 2-Thiobarbituric Acids

“…Metal nanoparticles offer new possibilities for designing and constructing structure controllable catalysts, which can be synthesized in a solvent or even be deposited on a support without obvious aggregation [32][33][34]. A variety of chemical methods have been developed for the preparation of metal nanoparticles [35] including those wherein, polymers carrying functional groups have been used as specific stabilizers for the solution synthesis of nanoparticles as they prevent irreversible aggregation of nanometer-sized metal particles due to steric repulsion [36,37] and also make them ''soluble'' in solvents.…”