Ab initio DFT cluster studies of angle-resolved NEXAFS spectra for differently coordinated oxygen at theV2O5(010) surface

At the (010) surface of vanadium pentoxide, V2O5, there are differently coordinated oxygen centers (1-, 2-, Mold) which can participate as active sites in specific oxidation reactions. In the present work we use ab initio density functional theory together with cluster models to calculate Is core excitation spectra of the differently coordinated oxygen centers at V2O5(010). Corresponding excitation energies and dipole transition moments are determined by details of local V-O-binding where the results vary strongly with oxygen coordination. As a result, a strong dependence of the (angle-resolved) excitation spectra on oxygen coordination is found. The differences can also be seen in the superimposed spectrum combining excitations from all oxygen centers. A comparison of our theoretical spectra with experimental near edge X-ray absorption fine structure data yields good agreement and allows an assignment of the experimental peaks to the different surface oxygen centers. (C) 2004 Elsevier B.V. All rights reserved.