Two-Dimensional Porous Beryllium Trinitride Monolayer as Multifunctional Energetic Material

Polynitrogen compounds have broad applications in the field of high-energy materials, making the exploration of two-dimensional polynitride materials with both novel properties and practical utility a highly attractive research challenge. Through global structure search methods and first-principles theoretical calculations at the Perdew-Burke-Ernzerhof (PBE) level of density functional theory (DFT), the globally minimum-energy configuration of a novel planar BeN₃ monolayer (tetr-2D-BeN₃) is predicted. This material exhibits a planar quasi-isotropic structure containing pentagonal, hexagonal, and dodecagonal rings, as well as "S"-shaped N6 polymeric units, exhibiting a high energy density of 3.34 kJ·g^-1, excellent lattice dynamic stability and thermal stability, an indirect bandgap of 2.66 eV (HSE06), high carrier mobility, and ultraviolet light absorption capacity. In terms of mechanical properties, it shows a low in-plane Young's stiffness of 52.3-52.9 N·m^-1 and a high in-plane Poisson's ratio of 0.55-0.56, indicating superior flexibility. Furthermore, its porous structure endows it with remarkable selectivity for hydrogen (H₂) and argon (Ar) gas separation, achieving a maximum selectivity of up to 10²³ (He/Ar). Therefore, the tetr-2D-BeN₃ monolayer represents a multifunctional two-dimensional polynitrogen-based energetic material with potential applications in energetic materials, flexible semiconductor devices, ductile materials, ultraviolet photodetectors, and other fields, thereby expanding the design possibilities for polynitride materials.