Design of three-dimensional B-C-N structures via tailoring GNRs and BNNRs

A series of porous 3D Cx(BN)y crystal structures with full sp2 hybridization are obtained by polymerizing edgefunctionalized graphene nanoribbons (GNRs) and boron nitride nanoribbons(BNNRs). Herein, the crystal structure and properties of Cx(BN)y are systematically and comprehensively investigated by first-principles calculations, deriving that it is feasible to achieve performance tuning by controlling the nanoribbon width. Thermodynamic stability, these structures have energy advantages with respect to the previously proposed B-C-N structures, and the thermodynamic stability of the structures deteriorates with the increase of the carbon content. Electrical properties, the bandgap value is tunable between 0.1 and 1.1 eV, and the bandgap value increases with the width of BNNRs at the same width of GNRs. Mechanical properties, these structures are mechanically stable, and exhibit unexpected superstretching properties, with tensile lengths up to 2.4 times the original length, bulk modulus tunable between 137-167GPa, shear modulus tunable between 81-115GPa, and the incompressibility of the structure decreases as the nanoribbon width increases.