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Langmuir 1999, 15, 674-681
Colloidal Gold Aerogels: Preparation, Properties, and Characterization Michele L. Anderson,† Catherine A. Morris,† Rhonda M. Stroud,‡ Celia I. Merzbacher,§ and Debra R. Rolison*,† Surface Chemistry Branch (Code 6170), Surface Modification Branch (Code 6670), and Optical Physics Branch (Code 5610), Naval Research Laboratory, Washington, D.C. 20375 Received June 30, 1998. In Final Form: November 24, 1998 Colloidal metal aerogels are composite nanoscale materials that combine the high surface area and porosity of aerogels with the unique optical and physical properties of metal colloids. As such, they are being developed as advanced sensor, catalytic, and electrocatalytic materials. We have prepared colloidal gold-silica aerogels containing gold colloids ranging in size from 5 to 100 nm. The results presented herein focus on 5- and 28-nm Au-containing silica aerogels for the initial characterization of the interaction between the metal colloid and the silica matrix. A blue-shift of the Au plasmon resonance for silicaimmobilized Au colloids (relative to the same colloids in a native Au sol) indicates an interaction between the Au colloid and the nanoscale silica network. Transmission electron microscopy measurements have been used to determine the average size and distribution of the colloidal Au particles, as well as to image the nanoscale silica environment supporting an immobilized Au colloid. Small-angle neutron scattering measurements show no significant changes in the three-dimensional structures of either the base- or acid-catalyzed silica aerogels upon incorporation of small amounts (
