Abstract
The understanding of reaction intermediates in heterogeneous catalysis has important implications for the design of novel catalysts. We investigate the adsorption of CO 2 on oxygen precovered Ag(100) at low temperature (17 K) by scanning tunneling microscopy and inelastic electron tunneling manipulation at 5 K. On the terraces, the adsorption leads to O-Ag-CO 2 -Ag-O compounds with reduced binding of the oxygen to the surface as compared to the separately adsorbed molecules. The compound can be either dissociated into a bistable O-Ag-CO 2 compound at 1.6 V, dissociated into its constituents at 2.2 V, or reacted at 6.5 V into a species, which we tentatively attribute to CO 3 . The thus obtained carbon trioxide or carbonate is an intriguing reaction intermediate, because it is not stable in the gas phase. Our detailed study of coadsorbed species outlines a possibility to investigate precursors of reactions that involve the substrate atoms. © 2010 American Chemical Society.