Stable two-dimensional Na decorated BeN4: a potential candidate for hydrogen storage

Abstract

To overcome the prevalent challenge of reversible hydrogen storage, surface activation by metal atom decoration holds a great promise, thus, boosting the hydrogen storage capacity. In this work, sodium (Na) decorated beryllonitrene (BeN₄) monolayer has been identified as a hydrogen storage material using first-principles calculations. Our results reveal that Na decorated BeN₄ has ability to adsorb upto 12 H₂ molecules, leading to high gravimetric density of 4.26 wt.%. The adsorption energy per H₂ (adsorbate) is moderate, i.e., between 0.13 and 0.298 eV, good enough for hydrogen storage in practical applications. AIMD simulations disclose that adsorbate experiences no kinetic hindrance in desorption. Moreover, the desorption temperature of H₂ molecule on NaBeN₄ monolayer (substrate) varies from 162.5 to 382 K, confirming the reversibility of substrate and thus ensuring its potential for hydrogen storage medium. The short recovery time predicts that the substrate responds rapidly in the presence of H₂ molecules, which guarantees the fast kinetics of adsorbate. Our calculations predict Na-decorated BeN₄ monolayer as an excellent candidate for reversible and high-capacity hydrogen storage material.