Hybrid assemblies of two-dimensional octagonal monolayers of C and BN*

In the dominating regime of hexagonal family, 2D octagonal monolayers (o-MLs) have emerged recently. High coordination cluster assembly route [J. Phys.: Condens. Matter 29, 335501 (2017)] is employed to form o-MLs of C and BN and their hybrid assemblies. The o-MLs are dynamically and thermally stable. Most of the MLs reveal charge transfer among atoms and asymmetric sp² hybridization. Hybrid assemblies can be tuned from metallic to insulating (4.13 eV). Stacking of zigzag buckled o-MLs forms stable body centered tetragonal bulk phase of C and BN. Dynamically stable nanotubes (NT), obtained by cutting chunk, with diameter 3.6 Å and 3.57 Å for o-C and o-BN respectively, can also be realized as vertically stacked o-rings and can be contrasted with the rolling of hexagonal ML. We thus report a CNT with a size smaller than the reported theoretical limit and synthesized experimentally till now.
Present work has established octagonal ring as a basic unit to form 1D, 2D and 3D materials of groups IV, III-V and II-VI. Studies of their properties, possible constraints, mechanism for stabilization, bonding and hybridization are fascinating and can unlock unusual facts for many applications.