Structure and reactivity of V2O5: bulk solid, nanosized clusters, species supported on silica and alumina, cluster cations and anions†
Abstract
Vanadyl bond dissociation energies are calculated by density functional theory (DFT). While the hybrid (B3LYP) functional results are close to the available reference data, gradient corrected functionals (BP86, PBE) yield large errors (about 50 to 100 kJ mol−1), but reproduce trends correctly. PBE calculations on a V20O62H24 cluster model for the (001) surface of V2O5 crystals virtually reproduce periodic slab calculations. The low bond dissociation energy (formation of oxygen surface defect) of 113 kJ mol−1
(B3LYP) is due to substantial structure relaxations leading to formation of V–O–V bonds between the V2O5 layers of the crystal. This relaxation cannot occur in polyhedral (V2O5)n clusters and also not for V2O5 species supported on