Changes of local electronic structure of perfect (VO)2P2O7(1 0 0) surface in response to oxygen vacancy formation: effect of electron trapping

This paper reports theoretical calculations based on density functional theory applied to investigate how the formation of oxygen vacancies modify the catalytic properties of the (VO)2P2O7(1 0 0) surface. Although a detailed understanding of the structure of the perfect surface is crucial, it must be stressed that in most practical cases oxide surfaces are defective and irregular. Among the various defects occurring in the metal oxides, the oxygen vacancy at the surface has received particular attention from both experimentalists and theoreticians. In spite of its simplicity this relatively common defect has very interesting properties. In this work one type of surface oxygen monovacancy is considered––the neutral Fs0 center i.e. vacancy with two trapped electrons. Electronic structures of vacancies at the (VO)2P2O7(1 0 0) surface are studied using a cluster model. The energetics of defect formation and the effect of electron trapping on the atomic arrangement is discussed. It is shown that the vacancies significantly modify the physical and chemical properties of the (VO)2P2O7(1 0 0) surface, thus influencing its catalytic behavior. A link between the sensitivity of the reactivity of the chemical system and the perturbation in the electronic density of the system due to the point anionic defects is demonstrated.