DFT cluster model study of MoVO-type mixed-metal oxides

Cluster models of the proposed active site of MoVO mixed-metal oxides (MMOs) have been explored computationally using density functional methods. Besides the density functional approximation, the size of the cluster models, the number of reduced metal centers, and the effect of the crystal environment on anionic cluster models have been examined. We studied the electronic structure of the MMO and, as a model reaction, the hydrogenation of a surface vanadyl group as well as the subsequent formation of a water molecule. For an adequate description of the electronic structure and the resulting reaction energies, it is necessary to use a density functional that accounts, at least partially, for the self-interaction error, e.g., the hybrid functional PBE0. To predict adequate reaction energies, one has to employ cluster models featuring at least two layers of the MoVO structure, so that inter-layer interactions can be modeled.