Nanoassembled model catalysts

A review with 96 refs. on the basis of specific examples taken from our lab., the most important steps in (i) prepg. supported nanoassembled model catalysts and (ii) investigating their size-dependent catalytic properties. We describe the cluster generation and present evidence for soft landing of the clusters onto solid surfaces. Subsequently, the growth and the characterization of the cluster support material, thin magnesium oxide films, are discussed, including the role of surface defects. Then the thermal stability of Cu clusters and the individual electronic structure of small Ag and Cu clusters on MgO are addressed. Finally, two examples of cluster size-dependent heterogeneous catalytic reactions are presented, (i) the cyclotrimerization of acetylene on nanoassembled Pd catalysts, and (ii) the CO oxidn. on nanoassembled Au catalysts. We show exptl. and together with first-principle calcns. that the interaction of such small metal clusters with the oxide surface strongly changes their catalytic properties. In contrast to large particles an addnl. electron in localized valence states of small clusters represents a major change. It is this charge transfer which turns inactive gold and palladium clusters into active model catalysts opening new perspectives to tune catalytic processes on the nanoscale. [on SciFinder(R)]     «

A review with 96 refs. on the basis of specific examples taken from our lab., the most important steps in (i) prepg. supported nanoassembled model catalysts and (ii) investigating their size-dependent catalytic properties. We describe the cluster generation and present evidence for soft landing of the clusters onto solid surfaces. Subsequently, the growth and the characterization of the cluster support material, thin magnesium oxide films, are discussed, including the role of surface defects. Th...     »