ADHESION OF RHODIUM, PALLADIUM, AND PLATINUM TO ALUMINA AND THE REDUCTION OF NO ON THE RESULTING SURFACES - A THEORETICAL-ANALYSIS

We report here approximate molecular orbital computations of adhesion and NO reduction in the three-way catalyst, modeled by a monolayer of either Rh, Pd, or Pt on the (0001)0 and (0001)Al faces of alpha-Al2O3. The support is not electronically innocent but affects NO reduction c apability significantly. Platinum and palladium form stable interfaces with both oxygen and aluminum faces. Only the aluminum interface is s table with rhodium. Depending on the nature of the interface, the Ferm i level of the composite systems varies dramatically. This, in turn, a ffects the adsorption mode, molecular or dissociative, of nitric oxide . From our study, it appears that an oxygen-platinum interface is best suited for both dissociative adsorption of NO as well as the coupling of two adsorbed nitrosyls to form a reduced dinitrosyl species with s ignificant N-N double-bond character.