Pentagonal B2N3-based 3D metallic boron nitride with high energy density

Abstract

Abstract Different from conventional insulating or semiconducting boron nitride, metallic BN has received increasing attention in recent years as its intrinsic metallicity grants it great potential for broad applications. In this study, by assembling the experimentally synthesized pentagonal B2N3 units, we have proposed the first pentagon-based three-dimensional (3D) metallic boron nitride, labeled penta-B4N7. First-principles calculations together with molecular dynamics simulations and convex hull diagram show that penta-B4N7 is not only thermally, dynamically and mechanically stable, but also three dimensionally metallic. A detailed analysis of its electronic structure reveals that the intrinsic metallicity comes from the delocalized electrons in the partially occupied antibonding N–N π orbitals. Equally important, the energy density of penta-B4N7 is found to be 4.07 kJ g−1, which is the highest among that of all the 3D boron nitrides reported so far.