DFT calculation insights into effects of N-doped WO3 at different sites on electronic structure, optical property and photocatalytic activity

The electronic structure and optical property of N-doped WO3 at different sites were calculated by B3LYP function. Although WO3 as a photocatalyst had deep level of the valence-band edge resulting in strong oxidizing ability, it was troubled by insufficient absorption of sunlight and low separation efficiency of carriers. The effects of O substitution by N in WO3 on its light absorption and charge separation were investigated. N-doping narrowed the band gap of WO3 and promoted the separation of electron and hole pairs. The O atom in WO3 was the most difficult to replace by N atom at site 2, followed by sites 1 and 3. The N2s-doped WO3 might demonstrate the highest photocatalytic activity, followed by N3s-doped WO3 and N1s-doped WO3 in sequence. This work will be beneficial to design promising WO3-based photocatalysts.