Beryllium Dinitride Monolayer: A Multifunctional Direct Bandgap Anisotropic Semiconductor with Polymeric Nitrogen, Oxygen Reduction Catalysis, and Potassium Ion Storage Ability

Abstract

Searching two-dimensional multifunctional polynitride materials with novel properties and practical applications is an attractive challenge. A global energy minimum of beryllium dinitride monolayer (α-2D-BeN2) is predicted with global structure search method and first-principles theory. With penta-, hexa-, and heptatomic rings and N4 tetramer in its planar anisotropic structure, α-2D-BeN2 monolayer possesses lattice dynamic stability, excellent thermal stability, a direct bandgap of 1.82 eV, high carrier mobilities, visible light absorption, large in-plane Poisson's ratio of 0.228 – 0.368, promising oxygen reduction catalysis, and outstanding potassium storage ability with ultrahigh specific capacity (2895 mAh·g–1), good voltage range (0.280 – 0.008 V), and low migration barrier energy (0.109 – 0.146 eV). Therefore, α-2D-BeN2 monolayer is expected to be an anisotropic multifunctional material to be applied in wide fields, such as semiconductor, visible-light detector, donor in solar cell, ductile material, iontronics device, and potassium ion anode material, enriching the possibility for polynitride materials.