Interaction between Monomeric Vanadium Oxide Clusters Supported on Titania and Its Influence on Their Reactivity

This is the authors' abstract. We don't add key points for this paper.

Density functional theory is used to study monomeric vanadium oxide clusters formed by exposing to oxygen a rutile TiO 2 (110) surface on which vanadium atoms have been preadsorbed. Past calculations examined such systems by using one V atom per supercell. This forces all VO x clusters to be identical and precludes interactions between them. To examine the consequences of this choice, we examine a VO x and a VO y cluster in the same supercell. We find that the most stable configuration is obtained when the supercell contains one VO 2 and one VO 3 cluster. The stabilization occurs because of a Lewis acid–base interaction: VO 2 donates electron charge to VO 3 and this lowers the energy substantially. No such interactions were found when the supercell contained VO x clusters with the same number of oxygen atoms. These finding demonstrate that in some cases it is essential to have two clusters in the supercell and that results obtained with one cluster in the supercell can be misleading. We have also studied the reactivity of the clusters with hydrogen, which is considered a descriptor of the ability of the cluster to catalyze the breaking of a C–H bond in an alkane.