Beryllium dinitride monolayer: a multifunctional direct bandgap anisotropic semiconductor containing polymeric nitrogen with oxygen reduction catalysis and potassium-ion storage capability

Abstract

Searching for two-dimensional multifunctional polynitride materials with novel properties and practical applications presents an attractive challenge. The global energy minimum of the beryllium dinitride monolayer (α-2D-BeN₂) was predicted using a global structure search method and first-principles theory. With penta-, hexa-, and hepta-atomic rings and an N₄ tetramer in its planar anisotropic structure, α-2D-BeN₂ monolayer exhibited lattice dynamic stability, excellent thermal stability, a direct bandgap of 1.82 eV, high carrier mobilities, visible light absorption, a large in-plane Poisson's ratio ranging from 0.228 to 0.368, promising oxygen reduction catalysis, and outstanding potassium storage capability with an ultrahigh specific capacity (2895 mA h g⁻¹), a good voltage range (0.280–0.008 V), and a low migration barrier energy (0.109–0.146 eV). Therefore, the α-2D-BeN₂ monolayer is expected to be an anisotropic multifunctional material with potential applications in various fields, such as semiconductors, visible-light detectors, donors in solar cells, ductile materials, iontronic devices, and potassium-ion anode materials, thereby expanding the possibilities for polynitride materials.