Stable Two Dimensional Na Decorated BeN4: A Potential Candidate for Hydrogen Storage

Abstract

Hydrogen, being a powerful energy carrier, possesses the ability to transform the present carbon economy to green hydrogen economy. Since wide range of resources are available for its production, reversible hydrogen storage is the prevalent challenge. Surface activation by adsorption has been reported to increase the hydrogen uptake, thus boosting the 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 hinderance 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 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.