Band gap engineering of (N, Ta)-codoped TiO2 : a first-principles calculation

The electronic properties and photocatalytic activity of X (N, C) / transition metal (TM=Ta, Hf, Fe) – codoped anatase TiO2 have been investigated using density functional theory. It was found that only the (N, Ta)-codoping case narrows the band gap significantly by about 0.48 eV, driven by the continuum-like p-d hybridized states above the top of valence band and d states at the bottom of conduction band. The calculated energy results suggest that codoping of Ta with N can increase the N concentration in N-doped TiO2 based on energy results.