Interplay between External Strain and Oxygen Vacancies on a Rutile TiO₂(110) Surface

Comprehensive first-principle calculations on strained rutile TiO₂(110) indicate that the formation energy of different types of oxygen vacancies depends on the external strain. For the unstrained state, the energetically favorable oxygen vacancy (EFOV) appears on the bridging site of the first layer; when 3% tensile strain along [11̅ 0] is applied, EFOV moves to the in-plane site, while 2% compressive strain along either [001] or [11̅ 0] shifts EFOV to the subbridging site. We therefore suggest that the distribution of oxygen vacancies can be engineered by external strain, which may help to improve the applications of a TiO₂ surface where oxygen vacancy plays an important role.