First principles study of two-dimensional Li3CX (X = S and Se) monolayers for hydrogen storage

Abstract

The persistent challenges in designing lightweight, reversible hydrogen storage materials are addressed by utilizing a density functional approach and ab initio molecular dynamics (AIMD) analysis of newly proposed Li₃CX (X = S and Se) monolayers. The pristine monolayers exhibit robust thermodynamic stability, and upon the sequential adsorption of a maximum of six hydrogen (H₂) molecules, they achieve significant gravimetric storage capacities of 15.67 wt% for Li₃CS and 9.80 wt% for Li₃CSe. The average adsorption energy (0.22 eV) of the H₂ molecule lies within the ideal range of cyclable physisorption, facilitating reliable hydrogen uptake and release under room temperature. Desorption temperatures decrease predictably with surface coverage, reaching 281 K for 6H₂@Li₃CS and 346 K for 6H₂@Li₃CSe, indicative of low-energy release potential. These results underscore the practical viability of the Li₃CX monolayers as a high-capacity, thermally stable, and structurally resilient hydrogen storage medium for next-generation clean energy technologies. Our investigations provide valuable insights for experimentalists exploring two-dimensional monolayers with practical hydrogen storage capabilities.