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 BeN monolayer (tetr-2D-BeN) 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, 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 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 (H) and argon (Ar) gas separation, achieving a maximum selectivity of up to 10 (He/Ar). Therefore, the tetr-2D-BeN 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.