Visible-light activity of N-LiInO 2 : Band structure modifications through interstitial nitrogen doping

Abstract Element doping is a promising strategy to improve the photo-response and photocatalytic activity of semiconductor photocatalyst with a wide band gap. To reduce the band gap of LiInO 2 that is considered as a novel photocatalyst, nitrogen-doped LiInO 2 (N-LiInO 2 ) is successfully fabricated by treating LiInO 2 and urea at 200 °C. It is found that interstitial instead of substitutional configurations are formed in the crystal structure of N-LiInO 2 due to the low-treating temperature and rich-oxygen conditions. The interstitial N-doping forms a doping state with 0.6 eV above the valence band maximum and a defect state with 0.1 eV below the conduction band minimum, reducing the band gap of LiInO 2 from 3.5 to 2.8 eV. N-LiInO 2 exhibits higher photocatalytic activity towards methylene blue (MB) degradation under 380 nm light irradiation, which is 1.4 times that of pure LiInO 2 . The enhanced photocatalytic activity of N-LiInO 2 is attributed to the extended light absorption and the improved charge carrier separation, which result in more reactive species participating in the photcatalytic process. This work provides a further understanding on tuning the band structure of semiconductor photocatalyst by N-doping strategies.