# Two-Dimensional Porous Beryllium Trinitride Monolayer as Multifunctional Energetic Material

## TL;DR

A new two-dimensional beryllium trinitride material is predicted to have high energy density and multiple useful properties for applications like energy storage and flexible electronics.

## Contribution

Prediction of a novel two-dimensional BeN3 monolayer with high energy density and multifunctional properties using global structure search and DFT calculations.

## Key findings

- tetr-2D-BeN3 has a high energy density of 3.34 kJ·g−1 and an indirect bandgap of 2.66 eV.
- The material shows excellent thermal stability and high selectivity for H2/Ar gas separation (up to 1023 He/Ar selectivity).
- It exhibits low in-plane stiffness and high flexibility, suitable for flexible semiconductor devices.

## Abstract

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.