Colloid synthesis of monodisperse Pd nanoparticles in layered silicates

Palladium nanoparticles have been generated in the interlamellar space of montmorillonite and kaolinite by different methods in aqueous media. The in situ preparation method was based on the preferential sorption of precursor ions (Pd2+) in the ethanol-rich interlamellar space of montmorillonite in ethanol(1)-water(2) binary liquid mixture and the subsequent reduction of Pd2+ ions to Pd-0 at 65 degreesC. A second method for the generation of nanoparticles was also carried out in aqueous suspension. However, nanoparticles were stabilized by polymers, the adsorption of which promoted the adhesion of nanocrystals to the silicate layers. A new method was developed to prepare Pd subcolloids in non-swelling kaolinite. The separation (complete disaggregation) of kaolinite lamellae was achieved by direct intercalation of dimethylsulphoxide (DMSO) at 65 degreesC. Neutral and cationic polymer/kaolinite intercalation complexes were obtained by adsorption from solutions. Characterization of these materials included ICP spectroscopy, XRD and pore-size distribution analysis. TEM measurements, which showed that nearly spherical, nearly monodisperse particles were generated. (C) 2001 Elsevier Science B.V. All rights reserved.