Insight into the effect of boron doping on electronic structure, photocatalytic and adsorption performance of g-C3N4 by first-principles study
Non-metal doping is an effective technique to adjust the electronic structure and modify the photocatalytic activity of graphitic carbon nitride (g-C3N4). On the basis of first-principles density functional theory, the formation energies, electronic, optical, and adsorption characteristics of boron doped monolayer g-C3N4 were determined. The results show that boron atom preferentially substitutes for the edge N2 atom. The energy band gap was reduced from 3.06 eV to 1.33-1.80 eV because of the introduction of boron impurity through three sites (N2, C1, interstitial). The strengthen delocalization of the HOMO and LUMO distribution caused by B-N2 and B-interstitial doping could facilitate the enhancement of the carrier mobility. The interstitial doped B atom acted as a bridge between two adjacent units, which is partly helpful to improve the carrier mobility and to separate photo-generated e-/h+ pairs. The absorption of visible light was also enhanced by the doping of B impurities. Furthermore, the interstitial doping of B atom significantly promoted the adsorption of pollutants by g-C3N4. The computational results could provide useful insights and effective strategies for design of non-metal photocatalysts.