A DFT study for hydrogen storage application on pristine magnesium dicarbide (MgC₂) monolayer

The hydrogen storage potential of pure MgC₂ was systematically investigated using density functional theory (DFT) calculations. The phonon dispersion and ab initio molecular dynamics (AIMD) simulations confirmed the dynamic and structural stability of MgC₂, reinforcing its suitability as a promising hydrogen storage material. The electronic structure analysis revealed that pure MgC₂ exhibits semiconducting behavior with a band gap of 0.25 eV, and transforms into a metallic state upon hydrogen adsorption. Hydrogen molecules were adsorbed onto the MgC₂ surface via physisorption, with an average adsorption energy of 0.286 eV, indicating moderate binding strength suitable for reversible hydrogen storage. Hirshfeld charge analysis demonstrated that MgC₂ transfers 0.041 e, 0.139 e, and 0.259 e to 1, 4, and 8 hydrogen molecules, respectively, highlighting charge redistribution upon adsorption. The calculated hydrogen storage capacity of 2.05% suggests a feasible adsorption mechanism. Additionally, AIMD simulations at 400 K confirmed that hydrogen adsorption does not induce significant distortions in the MgC₂ framework, further validating its thermal and mechanical stability. These findings underscore the potential of MgC₂ as an efficient hydrogen storage material for sustainable energy applications, offering a promising pathway for the development of next-generation clean energy technologies.