Atomic structures of V-Ti-O intermixed oxide monolayer on rutile TiO2(011) substrate predicted by extensive structural search

The formation of various structural V-Ti-O intermixed oxide monolayers on the rutile TiO2(011) substrates have been observed in experiments. The atomic structures and formation mechanism of them are still unclear. To this end, a global search of V-Ti-O ordered structures on rutile TiO2(011) surface is performed based on the evolutionary method. Nine energetically stable or metastable structures of different compositions are predicted, which can be considered as V-doping in different type of 2 x 1 reconstruction of rutile TiO2 (011) surface. The calculated electronic structures indicate that the V atoms in most structures are not fully oxidized and introduce localized impurity states in the band gap. The oxidation states of the V atoms and surface Ti atoms are determined. The stabilization regions of them are determined based on the calculated surface energies. Our results are instructive for the experimental synthesis of different structural V-Ti-O monolayers, and significant for deep understanding of the photo- or electro-catalytic properties of them.