THEORETICAL CLUSTER MODEL STUDIES OF BIMETALLIC HETEROGENEOUS CATALYSIS - DISSOCIATION OF HYDROGEN ON PURE AND RHENIUM-DOPED PT(1,O,O)

The chemisorption of hydrogen molecules on clusters of pure and rheniu m-doped platinum has been investigated as a possible model for reactio ns on the corresponding (1,0,0) surfaces. When rhenium replaces platin um at the chemisorption site, the shape of the potential energy surfac e undergoes a major change. The doped cluster has a higher hydrogen bi nding energy and also a higher barrier to further surface diffusion. T his indicates that, compared with the pure Pt surface, the doped compo und will have a higher preference for desorption of recombined hydroge n molecules.