First principles investigation of novel room temperature reversible hydrogen storage media: A Li-decorated 2D B7N5 monolayer

Hydrogen storage media play crucial roles in the realization of sustainable development. However, current materials face challenges in terms of storage capacity and operational conditions. Therefore, the development of novel materials is essential. In this study, we developed a complex structure by decorating Li ions on a two-dimensional (2D) B7N5 substrate, which exhibited multiple porous geometrical configurations, a superlight mass, and a large specific surface ratio, enabling reversible hydrogen storage under room conditions. Theoretical calculations demonstrated that doping with Li ions did not cause structural deformations of the pure 2D B7N5 material. Additionally, charge redistribution coupled with the unique structure of the B7N5 substrate created a regular polarization field that facilitated reversible hydrogen adsorption, with an adsorption energy of −0.23 eV/H2 at 293 K (room temperature) and 101 kPa (standard atmospheric pressure). Meanwhile, the gravimetric capacity reached an impressive 8.77 wt%, surpassing the Department of Energy requirement of 5.5 wt%. We anticipate that the structure and material will inspire further experimental and theoretical research leading to practical applications of hydrogen energy.