First-principles study of N-doped and N-V co-doped anatase TiO2

The ground state atomic configurations and electronic structures of anatase TiO2, N-doped TiO2 and N-V co-doped TiO2 are studied by the projector augmented wave method and the generalized gradient approximation plus U (Hubbard correction) (GGA+U) based on the density functional theory. The results indicate that the volume of cell is slightly larger and the ground state configuration has no change significantly for N-doped TiO2, but the symmetry of cell is broken and the position of V atom is more close to N atom after co-doping with N and V. The band gap of anatase TiO2 is calculated to be 3.256 eV, which is in agreement with experimental value (3.23 eV). When N is doped, the gap is reduced by more than 0.4 eV. but for N-V co-doped system, the gap reduces to 2.555 eV. Moreover, the acceptor level and donor level, which can be formed between the valence band maximum and the conduction band minimum because of co-doping with N and V, are more favorable to the separation of photoelectron-hole pairs and reduce the rate of recombination. Therefore, the co-doping of anatase TiO2 with N and V can effectively improve the photocatalytic performance of anatase.