Adsorption and Reaction on Oxide Surfaces: CO and CO₂ on Cr₂O₃(111)

Abstract

Abstract We have investigated the adsorption of CO and CO 2 on epitaxially grown Cr 2 O 3 (111) by means of EELS. LEED, ARUPS, NEXAFS and XPS. CO is found to adsorb on the oxide surface in an ordered (√3 × √3)R30° structure with the molecular axis oriented approximately parallel to the surface. CO 2 on the other hand reacts with the chromium oxide to form a surface carbonate. Adsorption of CO, respectively reaction of CO 2 only takes place on a clean, freshly flashed oxide surface. Preadsorption of oxygen leads to a surface which is rather inert to adsorption, likely due to electronic or steric reasons.