EXPERIMENTAL AND THEORETICAL-STUDIES OF FUEL-CELL CATALYSTS - DENSITY-FUNCTIONAL THEORY CALCULATIONS OF H-2 DISSOCIATION AND CO CHEMISORPTION ON FUEL-CELL METAL DIMERS

Gradient-corrected density functional theory (GC-DFT) calculations hav e been performed for molecular hydrogen, carbon monoxide and the metal dimers Pt-Pt, Pt-Ni, and Pt-Ru. The dissociative adsorption of molecu lar hydrogen on these metal dimers has been modelled. Derived potentia l energy surfaces for the dissociation of molecular hydrogen on these dimers are presented. Furthermore, the interaction with carbon monoxid e has been studied. Here we fmd that Pt-2 binds CO significantly stron ger than Pt-Ni and Pt-Ru. We present equilibrium geometries, calculate d binding energies, Mulliken charge distributions, and orbital energie s. Our results correlate well with our experimental studies of the hyd rogen electro-oxidation reaction in a proton-exchange fuel cell where the fuel to the anode (Pt/Pt alloy on carbon electrode) is hydrogen, p repared by reforming of methane, which contains trace amounts of carbo n monoxide.