Influence of anatase support on geometrical structure of vanadium oxide at varying temperatures and pressures. Periodic DFT study

Theoretical methods (periodic density functional theory) are used to investigate the vanadia−titania (V2O5/TiO2-anatase,1 Top. Catal. 2002, 21, 35) system, which is a very successful redox catalyst with a wide range of applications. A “basis set” of 12 species with the general formula VOxHy is used to construct a vanadium oxide overlayer on a TiO2-anatase support in a consistent way. Different structures are compared by means of thermodynamic analysis which also allows for the extrapolation of theoretical results to finite temperatures and pressures. Calculations show that the catalyst surface is very complicated (even within a simplified theoretical model) with many different structures that can coexist or transform one into another with slight changes of conditions. This may explain a wide range of different structures reported by experimentalists in the literature.