A first-principles study of hydrogen storage on MXene Mo₂C monolayer

This study investigates the potential of Mo₂C MXene as a hydrogen storage material using density functional theory (DFT) and molecular dynamics (MD) simulations to examine its structural stability, electronic properties, and hydrogen adsorption behavior. The optimized Mo₂C structure exhibits a hexagonal lattice with favorable adsorption sites over Mo atoms and shows a surface area expansion of approximately 4 % after hydrogen loading while maintaining lattice symmetry. Thermodynamic stability is confirmed through adsorption energy calculations, which reveal a clear relationship between energy levels and hydrogen concentration. The results indicate that H₂ adsorption on Mo₂C is a thermodynamically favorable and exothermic process, with adsorption energies ranging from -0.184 to -0.528 eV, satisfying the criteria for practical hydrogen storage applications. Charge transfer analysis identifies Mo atoms as electron acceptors. Density of States (DOS) calculations reveal a near-zero band gap, confirming the metallic nature of Mo₂C, while Projected DOS (PDOS) and orbital maps show significant hybridization and electronic polarization among H, Mo, and C atoms. Charge density difference maps highlight effective charge redistribution with strong electric fields around Mo atoms. MD simulations further confirm the structural stability of the Mo₂C-H₂ system, showing minimal deformation during a 100 ps simulation and supporting efficient hydrogen adsorption. Overall, these findings establish Mo₂C MXene as a promising candidate for hydrogen storage applications and provide valuable insights for experimental validation and further development of sustainable energy storage technologies.