Nitrogen doping concentration influence on NaNbO3 from first-principle calculations

The nitrogen concentration effects on electronic band structures and photocatalytic performance of N-doped sodium niobate (NaNbO₃) have been investigated by first-principles calculations based on density functional theory (DFT). At lower nitrogen doping levels, some localized N 2p states are formed above the valence band (O 2p) in N-doped NaNbO₃, leading to the reduction of the photon transition energy in comparison to that of undoped compound. Under higher doping levels, the N 2p states mix with O 2p states and then move the top of valence band upward. Two possible mechanisms for increasing visible light absorbance in N-doped NaNbO₃ are tentatively put forward according to the doping levels, which would be of importance in understanding and developing the visible-light-sensitive nitrogen-doped multimetal oxide.