Spectroscopic Observation of Dual Catalytic Sites During Oxidation of CO on a Au/TiO 2 Catalyst

The prevailing view of CO oxidation on gold-titanium oxide (Au/TiO(2)) catalysts is that the reaction occurs on metal sites at the Au/TiO(2) interface. We observed dual catalytic sites at the perimeter of 3-nanometer Au particles supported on TiO(2) during CO oxidation. Infrared-kinetic measurements indicate that O-O bond scission is activated by the formation of a CO-O(2) complex at dual Ti-Au sites at the Au/TiO(2) interface. Density functional theory calculations, which provide the activation barriers for the formation and bond scission of the CO-O(2) complex, confirm this model as well as the measured apparent activation energy of 0.16 electron volt. The observation of sequential delivery and reaction of…