Relative stability of low-index V2O5 surfaces: a density functional investigation

Abstract

Ab initio density functional calculations of the structural and electronic properties ofV2O5 bulk and its low-index surfaces are presented. For the bulk oxide and the (010) surface (thenatural cleavage plane) a good agreement with experiment and with earlier ab initiocalculations is found. For the first time, the investigations are extended to otherlow-index surfaces: (001) and (100). On both surfaces, termination conserving abulk-like stoichiometry is preferred, but—in contrast to the (010) surface—a strongstructural relaxation takes place. Relaxation reduces the surface energy from 1.16 to0.48 J m−2 for the (001) andfrom 0.61 to 0.55 J m−2 for the (100) surface. Although the relaxed surface energies are stillone order of magnitude higher than calculated for the (010) surface(0.047 J m−2), theWulff construction demonstrates that (001) and (100) surfaces contribute about 15% of the total surfacearea of a V2O5 crystallite, indicating a non-negligible role in the catalytic activity ofV2O5.