Preparation and catalysis of polymer-protected coinage metal nanoclusters

Preparation, characterization and catalyses of polymer-protected coinage metal nanoclusters were investigated, especially from the viewpoint of bimetallization. Poly (N-vinyl-2-pyrrolidone) (PVP)-protected Au/Rh bimetallic nanoclusters with an average diameter of 2.6 nm were prepared by alcohol reduction of HAuCl4 and RhCl3 in the presence of PVP. The Au/Rh bimetallic nanoclusters having an Au-core/Rh-shell structure work as more active catalysts for visible-light-induced hydrogen generation from water than the corresponding Au and Rh monometallic nanoclusters. Ag nanoclusters protected by poly(sodium acrylate) (PSA) were prepared by UV irradiation of an alcohol-water solution of silver perchlorate in the presence of PSA and were applied to the catalyst for oxidation of ethylene. The activity of Ag nanoclusters thus prepared remarkably increases with increasing the reaction temperature. Addition of cesium and rhenium ions increases the catalytic activity of PSA-Ag nanoclusters as well. Thus, PSA plays an important role in this system. PVP-protected Cu/Pd alloy nanoclusters were prepared by reduction in glycol at 198 degrees C, revealing high activity as a catalyst for hydration of acrylonitrile to acrylamide as well as for partial hydrogenation of 1,3-cyclooctadiene to cyclooctene.