Preparation of Pd0 nanoparticles stabilized by polymers and layered silicate

The synthesis of palladium nanoparticles on montmorillonite layer silicates was studied. The solid/liquid interfacial layer was utilized as a nanoreactor for the synthesis of particles in the interlamellar space. pd(2)+ ions are first adsorbed from acidic PdCl2 solution in an aqueous suspension of montmorillonite and are next reduced to Pd-0 by ethanol within the adsorption layer. Pd-0 nanoparticles appear and grow in the internal, interlamellar space as well as on the external surface of the lamellae. Another method for generation of nanoparticles was also carried out using aqueous polymer solutions in the presence of clay; however, the nanoparticles can be bond to the clay mineral lamellae. In the course of clay/polymer aggregation following reduction, the larger clusters formed in the bulk phase may become attached to the silicate layers via macromolecules acting as molecular bridges. The structure, specific surface area, porosity, etc., of montmorillonite are significantly altered by the incorporation of nanoparticles. These alterations were monitored by various techniques (N-2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM)). TEM is also eminently suitable for the determination of average particle size and size distribution functions. (C) 2001 Elsevier Science B.V. All rights reserved.