Direct Colloidal Route for Pt-Covered AuPt Bimetallic Nanoparticles

Pt-covered AuPt bimetallic nanoparticles were synthesized in a polar organic environment using HAuCl 4 and H 2 PtCl 6 as precursors. Electrochemical and UV−vis measurements showed that these AuPt nanoparticles have Pt-rich surfaces and their effective electrochemical Pt coverage is dependent on the Pt nominal composition. By mixing the two precursors in one pot, the interaction of two precursors lowered the temperature for Pt reduction and further favored the formation of a smooth Pt shell on the particle surface. The synthesis is a unique approach for controlling the surface electrochemical properties of bimetallic nanoparticles via varying particle nominal compositions.