Ti-decorated nitrogen-rich BeN4 monolayer for reversible hydrogen storage: DFT investigations

The metal-decorated two-dimensional materials have the potential to be considered as onboard hydrogen storage materials, as they have a high surface area and fast kinetics. Here, the application of titanium atom (Ti) decoration on the nitrogen-rich BeN4 monolayer for hydrogen storage is studied by means of Density Functional Theory (DFT). BeN4 is made up of five and six-membered rings and has been synthesized using high-pressure nanofabrication in the recent past. The binding energy of the Ti-decorated BeN4 monolayer comes out to be −2.04 eV indicating that an energetically stable complex is formed after metal decoration. The spin-polarized partial density of states (PDOS) implies that semimetal BeN4 becomes magnetic after Ti decoration. The charge transfer analysis validates transfer of charge from the Ti metal atom toward the BeN4 monolayer. The Ti-decorated BeN4 (BeN4 + Ti) can bind seven hydrogen molecules via Kubas interactions with average adsorption energy and desorption temperature of −0.36 eV/H2 and 512 K, correspondingly satisfying DOE’s criteria. The ab initio molecular dynamics (AIMD) simulations ensure the structural integrity of the BeN4 + Ti complex at 300 K. The high diffusion energy barrier reduces the probability of metal–metal clustering formation. The storage capacity of the BeN4 + Ti complex comes out to be 14.21 gravimetric wt% of hydrogen. The present electronic and molecular level study signifies that the Ti-decorated nitrogen-rich BeN4 monolayer has the potential to fulfill the requirements to be considered as an energy storage material.