Reversible Hydrogen Storage for NLi ₄-Decorated Honeycomb BoropheneOxide

Abstract

The boron-based two-dimensional (2D) materials decorated with functional groups NLi₄ has been numerically investigated for hydrogen storage via first principles calculations method. Strain-energy analysis and molecular dynamics simulations shows the pristine planar honeycomb B₂O has strong mechanical and thermal stability. Crystal Orbital Hamiltonian Population analysis confirmed that there exist stronger B-B/B-O covalent bonds within B₂O monolayer. In functional material, a local electric field around each lithium atom can be formed and the overall electronic structure is favorably changed for gas adsorptions. Both electrostatic forces and the van der Waals interaction are the dominant hydrogen-attached mechanisms of lithium cation. An anchored functional group NLi₄ can adsorb at most 11 hydrogen molecules, and the average adsorption energy per hydrogen molecules is around -0.20 eV, indicating high hydrogen storage capacity and reversible applicability. The highest hydrogen storage capacity can reach to 12.5 wt% at room temperature. The study shows the investigated material is a good candidate for hydrogen storge.

Keywords: Reversible hydrogen storage, NLi4-Decorated, Borophene oxide, First-principal calculation, DFT