Water-Gas Shift Catalysis at Corner Atoms of Pt Clusters in Contact with a TiO2 (110) Support Surface

The redox and associative carboxyl pathways of the water gas shift reaction have been investigated at a corner Pt site of the Pt/TiO2 (110) interface using density functional theory and microkinetic modeling techniques. Overall rates calculated from the microkinetic model suggest that the redox pathway dominates in the temperature range of 473-673 K and that the oxygen vacancy structure plays a critical role in dissociating H2O. Because of the strong adsorption of CO at the corner Pt atoms, these sites are less active than the edge Pt sites at low temperatures; however, the activity of corner atoms becomes higher above 573 K. The CO adsorption strength and the ability to dissociate H2O are the two main factors that determine the activity of a particular site or catalyst for the water gas shift reaction.