STRUCTURE AND CHEMICAL-COMPOSITION OF A SUPPORTED PT-RU ELECTROCATALYST FOR METHANOL OXIDATION

High resolution electron microscopy and X-ray microchemical analysis w ere used to characterize the composition, size, distribution, and morp hology of Pt-Ru particles with nominal Pt:Ru ratios of 1:1 and 3:1, su pported on carbon black. The particles are predominantly single nanocr ystals with diameters in the order of 2.0 to 2.5 nm. Occasionally, twi nned particles are also observed. All investigated particles represent solid solutions of Pt and Ru with compositions very close to the nomi nal one. Based on two-dimensional projection in high resolution images , it is suggested that the well-resolved particles are of cubooctahedr al shape. In addition to {200} and {111} facets, {113} facets are also observed. (C) 1995 Academic Press, Inc.