New crystal structure prediction of fully hydrogenated borophene by first principles calculations

We predict by first principles calculations that the recently prepared borophene is a pristine two-dimensional (2D) monolayer superconductor, in which the superconductivity can be significantly enhanced by strain and charge carrier doping. The intrinsic metallic ground state with high density of states at Fermi energy and strong Fermi surface nesting lead to sizeable electron-phonon coupling, making the freestanding borophene superconduct with $T_c$ close to 19.0 K. The tensi...

Borophene has triggered a surge of interest due to its outstanding properties including mechanical flexibility, polymorphism, and opto-electrical anisotropy. Very recently, a novel semi-hydrogenated borophene, called $\alpha'$-4H, was synthesized in large-scale freestanding samples, which exhibits excellent air-stability and semiconducting nature. Herein, using the density functional theory (DFT) and many-body perturbation theory (MBPT), we investigate the electronic and exci...

We report a previously unknown monolayer borophene allotrope and we call it super-B with a flat structure based on the ab initio calculations. It has good thermal, dynamical, and mechanical stability compared with many other typical borophenes. We find that super-B has a fascinating chemical bond environment consisting of standard sp, sp2 hybridizations, and delocalized five-center three-electron $\pi$ bond, called $\pi$(5c-3e). This particular electronic structure plays a pi...

We introduce two-dimensional borane, a single-layered material of BH stoichiometry, with promising electronic properties. We show that, according to Density Functional Theory calculations, two-dimensional borane is semimetallic, with two symmetry-related Dirac cones meeting right at the Fermi energy $E_f$. The curvature of the cones is lower than in graphene, thus closer to the ideal linear dispersion. Its structure, formed by a puckered trigonal boron network with hydrogen a...

We report first principle calculations of electronic and mechanical properties of few-layer borophene with the inclusion of interlayer van der Waals (vdW) interaction. The anisotropic metallic behaviors are preserved from monolayer to few-layer structures. The energy splitting of bilayer borophene at $\Gamma$ point near the Fermi level is about 1.7 eV, much larger than the values (0.5--1 eV) of other layered semiconductors, indicating much stronger vdW interactions in metalli...

Using density functional theory combined with a semi-empirical van der Waals dispersion correction, we have investigated the stability of lattice defects including boron vacancy, substitutional and interstitial X (X=H, C, B, N, O) and $\Sigma$5 tilt grain boundaries in borophene and their influence on the anisotropic mechanical properties of this two-dimensional system. The pristine borophene has significant in-plane Young's moduli and Poisson's ratio anisotropy due to its st...

The structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron have been studied by first-principles calculations. Both a-boron and a*-boron consist of equivalent icosahedra B12 clusters in different connecting configurations of "3S-6D-3S" and "2S-6D-4S", respectively. The total energy calculations show that a*-boron is less stable than a-boron but more favorable than beta-boron and Gamma-boron at zero pressure. Both a-boron and a*-...

Recent success in synthesizing two-dimensional borophene on silver substrate attracts strong interest in exploring its possible extraordinary physical properties. By using the density functional theory calculations, we show that borophene is highly stretchable along the transverse direction. The strain-to-failure in the transverse direction is nearly twice as that along the longitudinal direction. The straining induced flattening and subsequent stretch of the flat borophene a...

Fast-growing electronics industry and future energy storage needs have encouraged the design of rechargeable batteries with higher storage capacities, and longer life times. In this regard, two-dimensional (2D) materials, specifically boron and carbon nanosheets, have garnered enthusiasm due to their fascinating electronic, optical, mechanical and chemical properties. Recently, a hydrogen boride (HB) nanosheet was successfully fabricated showing remarkable stability and super...

The effect of external static charging on borophenes - 2D boron crystals - is investigated by using first principles calculations. The influence of the excess negative charge on the stability of the 2D structures is examined using a very simple analysis of decomposition of the binding energy of a given boron layer into contributions coming from boron atoms that have different coordination numbers. This analysis is important to understand how the local neighbourhood of an atom...