Hydrogenated and halogenated MB (M=As, Sb and Bi) monolayers: Structural, electronic, optical and topological properties by first principles calculations

Abstract The electronic and optical properties of the functionalization of MB (M = As, Sb and Bi) by hydrogen and halogen atoms, namely MBX2 are investigated by first principles calculations. The analysis of the phonon spectra show that all the structures are dynamically stable. The electronic structures indicate that AsBH2 and SbBH2 are suitable catalyst for water splitting, while, BiBI2 and BiBBr2 are intrinsic 2D topological insulators with a large gap of 0.43 eV. Interestingly, BiBCl2, BiBH2, SbBBr2, AsBBr2, SbBCl2 and AsBCl2 monolayers can transform trivial to nontrivial phases under the tensile strain of 2, 10, 10, 12, 14 and 18%, respectively. This work indicates that the functionalized groups can effectively broaden the applications of MBX2 for water splitting and good topological insulators by tuning the band gaps and the band edges under tensile strains.