Penta-B(x)N(y) sheet: a density functional theory study of two-dimensional material

By using density functional theory with generalized gradient approximation, we have carried out detailed investigations of two-dimensional B(x)N(y) nanomaterials in the Cairo pentagonal tiling geometry fully composed of pentagons (penta-B(x)N(y)). Only penta-BN and BN(2) planar structures are dynamically stable without imaginary modes in their phonon spectra. Their stabilities have been further evaluated by formation energy analysis, first-principles molecular dynamics simulation, and mechanical stability analysis. Penta-BN(2) is superior to penta-BN in structural stability. Its stability analysis against oxidization and functional group adsorption as well as its synthesizing reaction path analysis show possibilities in fabricating penta-BN(2) on experiment. Furthermore, the penta-BN(2) could be transferred from metallic to semiconducting by ionizing or covalently binding an electron per dinitrogen. Also, it has been found to have superior mechanical properties, such as the negative Poisson’s ratio and the comparable stiffness as that of hexagonal h-BN sheet. These studies on the stabilities, electronic properties, and mechanical properties suggest penta-BN(2) as an attractive material to call for further studies on both theory and experiment.