Exploring the hydrogen storage possibility of the pristine, defected and metals decorated o-B2N2 monolayers: Insights from DFT simulations

To explore the possibility of hydrogen storage, we conducted dispersion-corrected density functional theory (DFT-D3) simulations on pristine, defected and metals (including Na and K alkali metals, Be, Mg and Ca alkaline-earth metals and Sc, Ti, Y and Zr transition metals) decorated orthorhombic diboron dinitride (o-B2N2) monolayers. The results suggest that the pristine, defected and metals (Na, K, Be, Mg, Ca, Sc, Y and Zr) decorated o-B2N2 monolayers are not desirable medium for storage of hydrogen. However, the Ti decorated o-B2N2 monolayer showed promising potential for hydrogen storage medium. The Ti atom displayed a significant binding energy (Eb) of −2.79 eV with the o-B2N2 monolayer, causing a reduced band gap and increased conductivity. In the case of Ti decorated o-B2N2 monolayer, the adsorption energy (Ead) for first hydrogen adsorption is −0.47 eV, meeting the department of energy (DoE)'s criteria. In addition, a charge donation from the Ti metal to o-B2N2 monolayer has been observed through PDOS, Löwdin charge transfer and charge density difference. The two Ti decorated o-B2N2 monolayer can bind a total of thirty-four hydrogen molecules within the DoE's limit, with Ead of −0.31 eV/H2 and 396 K of desorption temperature. The calculated gravimetric storage capacity is 11.21 %, which is remarkably higher than the DoE's specified range. Ab initio molecular dynamics calculations predict a favourable thermal stability of two Ti decorated o-B2N2 monolayer at 396 K. As a summary, this research highlights the promising prospects of the Ti decorated o-B2N2 monolayer as an efficient medium for high-capacity hydrogen storage.