Exploring reversible hydrogen storage capacity of Li and Na metal-decorated Sc3N2 monolayer via DFT calculations

This study contains a systematic investigation of gravimetric storage capacity of hydrogen molecules (H2) facilitated by lithium (Li) and sodium (Na) decoration on a Sc3N2 MXene monolayer using first-principle's calculations. To determine the most stable adsorption sites for the metal atoms, the results indicate that the C site is the most favorable site for Li decoration and T site is the most stable for Na decoration as each site resulted in favorable binding energy. These sites confirm the covalent and ionic bonding between the metal and Sc atoms. Considering the stable sites, the parallel adsorption of five H2 molecules on both Li and Na metal atoms are analyzed and obtained the lowest adsorption energies. To further understand the adsorptive behavior of H2 molecules on the Li and Na decorated Sc3N2 MXene monolayer partial density of states (PDOS), Hirshfeld charge analysis, electron localization function (ELF). Moreover, thermal stability is analyzed with thermodynamic study and desorption temperature calculated which have confirmed the presence of Kubas and weak electrostatic nature of material. Afterwards, hydrogen storage capacities of the considered metal decorated MXenes monolayers are obtained as: 5.9 wt% for Li-decorated Sc3N2 & sdot;5H2 and 5.6 wt% for Na-decorated Sc3N2 & sdot;5H2. These findings demonstrated that the investigated MXenes monolayers are reliable and outstanding materials for hydrogen storage applications.