Synthesis and electrocatalytic oxygen reduction activity of graphene-supported Pt3Co and Pt3Cr alloy nanoparticles

Graphene-supported Pt and Pt3M (M = Co and Cr) alloy nanoparticles are prepared by ethylene glycol reduction method and characterized with X-ray diffraction and transmission electron microscopy. X-ray diffraction depicted the face-centered cubic structure of Pt in the prepared materials. Electron microscopic images show the high dispersion of metallic nanoparticles on graphene sheets. Electrocatalytic activity and stability of the materials is investigated by rotating-disk electrode voltammetry. Oxygen reduction activity of the Pt3M/graphene is found to be 3-4 times higher than that of Pt/graphene. In addition, Pt3M/graphene electrodes exhibited overpotential 45-70 mV lower than that of Pt/graphene. The high catalytic performance of Pt3M alloys is ascribed to the inhibition of formation of (hydr) oxy species on Pt surface by the alloying elements. The fuel cell performance of the catalysts is tested at 353 K and 1 atm. Maximum power densities of 790, 875, and 985 mW/cm(2) are observed with graphene-supported Pt, Pt3Co, and Pt3Cr cathodes, respectively. The enhanced electrocatalytic performance of the Pt3M/graphene (M = Co and Cr) compared to that of Pt/graphene makes them a viable alternative to the extant cathodes for energy conversion device applications. (C) 2010 Elsevier Ltd. All rights reserved.