The effect of the "metal-support" interaction on the metallic nanosystems state

The paper deals with the results of the investigation "in situ" of the effect of the interaction of the "metal-support" (SiO2, Al2O3, ion-exchange resin) on the size particles and the surface state of Pd, Pt, Rh-Co, Ir-Co and Rh-Co-Ir nanosystems. The information concerning the surface state can be obtained by studying the chemisorbed test-molecule (CO), using IR-spectroscopy. The investigation of the dispersity has been performed with a wide and a small angles X-ray scattering. It was shown that the nature of the support influences only the average particle size changes but it does not influence the surface composition for Pd, but it affects both particle size and surface composition for Pt-systems. A clear trend is evident for metal particle size SiO2>Al2O3>ion-exchange resin. It has been found out that the interaction "metal-support" decreases in the following order: ion-exchange resin>Al2O3>SiO2. In the case of bi- and multimetallic nanosystems the change of the surface state depending on the support, i.e. the redistribution of M+, Mdelta+, and Mo- sites, was observed. (C) 2004 Published by Elsevier B.V.