PLATINUM-PROMOTED CATALYSIS BY CERIA - A STUDY OF CARBON-MONOXIDE OXIDATION OVER PT(111) CEO2/

The structure and reactivity of a series of Pt(111)/ceria model cataly sts have been studied as a function of ceria coverage and morphology. XPS and LEED data show that the method of preparation results in growt h of disordered CeO2 which converts to epitaxial (111)-oriented ceria upon annealing at >700 K. Submonolayer ceria coverages strongly promot e the oxidation of CO. Most strikingly, the fully encapsulated Pt(111) wafer is a much more effective catalyst than the bare metal itself. D isordered encapsulating films are much more active than ordered films. The results are discussed in terms of Pt-promoted oxygen vacancy form ation in ceria and the predicted relative reactivity of principal crys tal faces of the oxide.