First-principles insights of electronic and optical properties of F-doped hexagonal boron nitride nanosheets for photo-catalytic water splitting

Two-dimensional hexagonal boron nitride nanosheets ( h -BNNSs) have a wide band-gap of over 6.0 eV, which makes them pervious to visible light. In the current report, based on first-principles calculations, we demonstrate that h -BNNS bi-layers can be converted to visible light absorption materials through band-gap tuning carried out by fluorine (F) doping. Bi-layer structures with different F doping ratios can be formed via van der Waals interaction, whose band-gaps are greatly reduced comparing with those of pure h -BNNS bi-layers and isolated h -BN mono-layers. Furthermore, the optical absorption of F-doped h -BNNS bi-layers is observably enhanced in the ultraviolet-visible light range, which makes F-doped h -BNNS bi-layers potential metal-free visible-light–driven photo-catalyst for water splitting.