MoB₂: A new multifunctional transition metal diboride monolayer

Several layered transition metal borides can now be realized by a simple and general fabrication method (Fokwa et al 2018 Adv. Mater. 30 1704181), inspiring our interest to transition metal borides monolayer. Herein, we predict a new two-dimensional (2D) transition metal diboride MoB₂ monolayer (ML) and study its intrinsic mechanical, thermal, electronic, and transport properties. The MoB₂ ML has isotropic mechanic properties along the zigzag and armchair directions with a large Young's stiffness, and has an ultralow room-temperature thermal conductivity. The Mo atoms dominate the metallic nature of MoB₂ ML. It shows an obvious electrical anisotropy and a current-limiting behavior. Our findings suggest that MoB₂ ML is a promising multifunctional material used in ultrathin high-strength mechanical materials, heat insulating materials, electrical-anisotropy-based materials, and current limiters. It is helpful for the experimentalists to further prepare and utilize the transition metal diboride 2D materials.