2D boron-nitride featuring B4 tetrahedros: An efficient photocatalyst for water splitting

Abstract

Two-dimensional hexagonal boron nitride (h-BN) is an insulator with polar covalent B−N bonds. Based on current research on boron-nitrogen 2D materials and the cluster assembling method, here, we designed five novel monolayers with square lattice formed by tetrahedral B4 units covalently linked to V-group atoms, namely the B4N2, B4P2, B4As2, B4Sb2, and B4Bi2 monolayers, via first-principles calculations. Both the B4N2 and B4P2 have good stability, as demonstrated by high cohesive energies, all positive phonon modes, high in-plane Young's modulus and structural integrity through 5 ps's molecular dynamics simulations at both 300 and 500 K. Moreover, the B4P2 monolayer exhibits metallic properties, whereas the B4N2 monolayer is an indirect bandgap semiconductor with the bandgap of 2.56 eV and appropriate band edge positions, the optical adsorption in UV light region, and high electron mobility for photocatalytic water splitting. Our theoretical study adds new members of 2D boron nitrides (B4N2), which can be used as an efficient photocatalyst for water splitting.