Surface oxygen in catalysts based on transition metal oxides: What can we learn from cluster DFT calculations?

Cluster model studies by means of ab initio DFT method are performed to examine electronic properties of different surface O atoms in several VOX systems and to correlate them with catalytic behavior. Since chosen compounds vary in metal oxidation state and in X element, reactivity of differently coordinated surface O is studied as a function of different parameters such as coordination number, geometrical and chemical environment. In addition, the mobility of different surface oxygen species, formation of surface oxygen vacancies and the adsorption of O2 molecule at the different vacancy is discussed on the examples of the V2O5 and MoO3 systems.