Formation of Crystalline Nanoclusters of Ag, Cu, Os, Pd, Pt, Re, or Ru in a Silica Xerogel Matrix from Single-Source Molecular Precursors

Abstract

Metal complexes containing bifunctional ligands which possess alkoxysilyl functional groups have been prepared for seven metals of the first, second, or third transition metal series. Incorporation of these single-source precursors into silica xerogel matrixes using sol−gel chemistry affords molecularly doped xerogels. Subsequent thermal treatment of these doped xerogels under reducing or oxidizing-then-reducing conditions affords nanoclusters of Ag, Cu, Os, Pd, Pt, Re, or Ru which are highly dispersed throughout the bulk of the xerogel matrix. Characterization of these nanocomposite materials by TEM, EDS, XRD, and electron diffraction indicates that the metal nanoclusters are highly crystalline. A visible spectrum of the silver nanocomposite shows the expected surface plasmon resonance near 415 nm.

Conductive sol–gel films

“…1,2 ), with metal particles, 3 or with dissolved salts. [4][5][6] Other methods have utilized direct metallization of the porous sol-gel matrix, by electrochemical reduction, [7][8][9][10] irradiation, 11 thermal treatment of dopants, 12 reduction reactions, 3,13 or by self-propagating hightemperature synthetic methods. 14 Approaches to immobilize metallic nanoparticles in sol-gel matrices [15][16][17][18] result in 10 to 100 fold conductivity increase 19,20 at the percolation threshold of particles.…”

Effect of calcination on microstructure and antibacterial activity of silver‐containing silica coatings

“…Alternative to some other processing techniques such as melt quenching, ion implantation, sputtering, and ion exchange, one easy way of preparing silver‐introduced coatings on glass or silica substrates is the sol–gel route. This can be achieved by dissolving silver salts in the sol and subsequent reduction of Ag + to metallic particles by using a reducing agent,23, 24 UV or gamma rays,25, 26 or by thermal treatment in reducing atmosphere 27–29. For sol–gel‐derived silver nanoparticle containing silica coatings, most work has been dedicated on exploring of metallic silver formation mechanism during thermal densification, while the number of investigations on direct correlation of antibacterial activity with structural and chemical changes of the coating surface due to thermal treatment is yet quite limited 9, 30…”

Self-Assembly of Silver−Aminosilica Nanocomposites through Silver Nanoparticle Fusion on Hydrophobic Surfaces

“…Formation of sol−gel layers can be achieved through self-assembly of surface-bound silane , or bioinspired and solution deposition techniques , . Synthesis or immobilization of metallic nanoparticles in nanocomposite can be carried out using bioinspired approaches , , synthesized through reductive hydride terminal groups , immobilized using polyelectrolytes , thermal treatment , radiation , or spontaneous reduction within silica matrix , . Fabrication of silica matrix that contains metallic nanoparticles can be performed after synthesis of nanoparticles, examples are direct nanoparticle encapsulation , , and self-assembly of silica coated nanoparticles , .…”