Abstract
Abstract: The electronic properties of defected TiO2 were investigated using the first-principles
calculations based on density functional theory and generalized gradient approximation. Three
typical defects, oxygen vacancy, titanium interstitial, and titanium vacancy, were considered in
three TiO2 polymorphs, anatase, rutile, and brookite, respectively. Our calculations demonstrated
that defect band is formed by removing oxygen atom from or inserting interstitial Ti atom into
the TiO2 lattice, which is responsible for the improvement of photocatalytic ability due to the
enhanced visible-light absorption. Our calculations further revealed that the defect formation
energy increases as following brookite, anatase, and rutile, indicating that defects are easy to be
created in brookite TiO2. The relatively high defect density and wide defect band contribute to
the better photocatalytic performance of brookite TiO2 in visible light.
