The Role of Atomic Vacancy on Water Dissociation over Titanium Dioxide Nanosheet: A Density Functional Theory Study

The interaction of water with titanium dioxide (TiO2) nanosheets has been studied under the framework of density functional theory plus Hubbard model. Particularly, the effect of an oxygen vacancy and a titanium vacancy on the dissociation of water has been investigated. It is found that molecular adsorption is favored on perfect TiO2 nanosheets and a titanium vacancy, while over an oxygen vacancy water prefers to dissociate spontaneously due to the strong bonding between water and unsaturated titanium and oxygen. With the formation of water water hydrogen bonds, dissociated water can be further stabilized. The role of titanium and oxygen vacancies is further discussed from the viewpoint of electronic structure.