Two novel triangular borophenes BH and BO: first-principles prediction.

By means of density functional theory calculations, we successfully predict two stable 2D triangular borophenes, namely BH and BO. Our results indicate that BH is a Dirac material and its cone point is located at the K point of the Brillouin zone (BZ). BO is identified as having a node-line ring and Dirac cones together. Its node-line ring formed by the intersection of the extended energy band from the two Dirac cones located on K point. This modified 2D borophene has great thermal and dynamic stability due to the electron transfer from the triangular boron lattice to the O atoms. The electronic structure of BO nanofilm demonstrates novel properties such as two Dirac cones, more than 1.3 eV linear dispersion bands at some points of the BZ, as well as excellent transport properties for the extremely high mobility brought by the combination of the node-line semimetal and Dirac cones. Our study may motivate potential applications of 2D materials in nanoelectronics.