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.