Cluster and periodic ab initio calculations on the adsorption of CO 2 on the SnO 2(1 1 0) surface

Abstract

The interaction of CO 2 with the Sn cations and the bridging oxygen anions sites of the SnO 2(1 1 0) surface has been investigated by means of gradient corrected density functional theory calculations and cluster models and periodic slabs. CO 2 interacts electrostatically with the five-coordinated Sn cations; the molecule is bound with the molecular axis perpendicular to the surface and is slightly distorted compared with the gas-phase molecule. On the bridging oxygen anions and in the limit of zero coverage, CO 2 is chemisorbed with the formation of a surface carbonate; the process, however, is almost thermoneutral and the chemisorbed state is metastable. As the coverage increases, the adsorbate–adsorbate repulsion make the formation of chemisorbed CO 2 unfavorable. The non-defective SnO 2 surface exhibits therefore very little reactivity towards CO 2.