Hexagonal boron-carbon fullerene heterostructures; Stable two-dimensional semiconductors with remarkable stiffness, low thermal conductivity and flat bands

Abstract: Among exciting recent advances in the field of two-dimensional (2D) materials, the successful fabrications of the C60 fullerene networks has been a particularly inspiring accomplishment. Motivated by the recent achievements, herein we explore the stability and physical properties of novel hexagonal boron-carbon fullerene 2D heterostructures, on the basis of already synthesized B40 and C36 fullerenes. By performing extensive structural minimizations of diverse atomic configurations using the density functional theory method, for the first time, we could successfully detect thermally and dynamically stable boron-carbon fullerene 2D heterostructures. Density functional theory results confirm that the herein predicted 2D networks exhibit very identical semiconducting electronic natures with topological flat bands. Using the machine learning interatomic potentials, we also investigated the mechanical and thermal transport properties. Despite of different bonding architectures, the room temperature lattice thermal conductivity of the predicted nanoporous fullerene heterostructures was found to range between 4 to 10 W/mK. Boron-carbon fullerene heterostructures are predicted to show anisotropic but also remarkable mechanical properties, with tensile strengths and elastic modulus over 8 and 70 GPa, respectively. This study introduces the possibility of developing a novel class of 2D heterostructures based on the fullerene cages, with attractive electronic, thermal and mechanical features.