Computational evaluation of lithium functionalized Penta-BN2 as promising reversible hydrogen storage

Abstract

Finding advanced hydrogen storage materials with high capacity and high efficiency is a key issue for hydrogen transportation and application. In this study, the first-principles calculation method is used to examine the potential of 2D pentagonal BN2 (Penta-BN2) as an excellent hydrogen storage material. The results indicate that Penta-BN2 has superior metallic and structural stable properties. The pristine Penta-BN2 is found to have weak adsorption energy for H2 molecules, which cannot meet the requirements of hydrogen storage. However, the Li-functionalized Penta-BN2 substrate is found to be relatively excellent to adsorb H2 molecules. A Li atom is bound closely to Penta-BN2 with large adsorption energy reaching more than 3.79 eV, and the 2 × 2 × 1 Penta-BN2 supercell can be suitably accommodated 4 Li atoms. 4Li-functionalized Penta-BN2 stores up to 16H2 molecules with a hydrogen gravimetric density of 8.70 wt%. The adsorption and desorption capacity of the system for H2 molecules under practical temperature and pressure conditions are investigated with semi-empirical calculations. The maximum reversible hydrogen storage capacity is up to 7.92 wt% between the practical condition of 30 atm/233 K for adsorption to 3 atm/358 K for desorption, which is better than other 2D pentagonal materials and boron-nitrogen compounds. The proposed investigations of this work illustrate that Li-functionalized Penta-BN2 is a promising hydrogen storage material with high efficiency, reversibility, and high-capacity characteristics.