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Abstract:
The Pd(111) surface has been extensively used as a model substrate to study CO oxidation. The reverse reaction, CO2 dissociation, however, has not been investigated to a comparable extend on this surface. We report angle-resolved photoemission studies on the system CO2 (+Na)/Pd(111). On a clean Pd(111) surface at 85 K no CO2 adsorption takes place. Upon small precoverages of Na, adsorption of CO2 occurs at T = 85 K. Via an analysis of the angular dependence of the photoelectron spectra we obtain information about the orientation of the adsorbed molecules. Upon annealing the surface to 125 K, CO2 reacts to form co-adsorbed CO and O. For a thick Na film on Pd(111) we also find CO2 adsorption but the reaction of the adsorbed species occurs along different reaction channels, ending at adsorbed carbonate species.
