Umicore Ag & Co Kg

Clarkson University

Brendan P Farrell

Dan V Goia

Egon Matijevic

Krishna Balantrapu

Benjamin Morrow

The present invention is directed to a method for preparing colloidal dispersions of precious metal nanoparticles selected from the group consisting of Pt, Au, Pd, Ag, Rh, Ru and mixtures or alloys thereof, and to a method for isolating such precious metal nanoparticles from these colloidal dispersions. The colloidal dispersions are prepared by reducing suitable precious metal precursor compounds in aqueous alkaline solutions at reaction temperatures between 40 and 70&#xb0; C. and a pH&#x2267;12.0 in the presence of polysaccharides with average molecular weights (M) in the range of 300,000 to 1,000,000. The precious metal nanoparticles are isolated after decomposing the polysaccharide by heating the colloidal dispersions to temperatures &#x3e;80&#xb0; C. The nanoparticles can be used for the manufacture of core/shell-type catalyst materials and for electronic, decorative and medical applications.

Method for preparing dispersions of precious metal nanoparticles and for isolating such nanoparticles from said dispersions

The invention provides an aqueous solution-based method for producing nanosized silver platelets, which employs the controlled mixing of a silver ion solution, a reducing solution, and an acidic solution in the presence of palladium ions.

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Cranston, RI, United States of America

Brendan P Farrell