Computational Design of Transition‐Metal‐Doped C2O Monolayers for Efficient and High‐Capacity Hydrogen Storage

Abstract

The present work demonstrates the impressive H2 storage performance of the experimentally synthesized C2O monolayer decorated with selected transition metals (TMs), namely Sc, Ti, and V. The transition metals are strongly adsorbed on C2O, with all three, Sc, Ti, and V, exhibiting robust and stable anchoring. Ab initio molecular dynamics simulations confirm the structural stability of the TM‐doped C2O systems up to 600 K, while their dynamical stability is verified through phonon calculations. Furthermore, nudged elastic band calculations reveal substantial energy barriers for metal migration (Sc = 2.47 eV, Ti = 2.48 eV, and V = 2.37 eV), indicating the absence of metal aggregation and clustering effects. Electronic structure calculations reveal that pristine C2O is semiconducting (2.06 eV), whereas TM incorporation induces metallic behavior with enhanced conductivity. The TM‐decorated C2O monolayer efficiently adsorbs up to five H2 molecules per metal site through synergistic electrostatic and van der Waals interactions. Remarkably, the Sc‐, Ti‐, and V‐decorated C2O monolayers deliver theoretical gravimetric hydrogen storage capacities of 8.69, 8.47, and 6.72 wt%, respectively, all exceeding the 5.50 wt% benchmark set by the US Department of Energy (DOE) for 2025. At full hydrogenation, the average H2 adsorption energies are calculated to be −0.26, −0.47, and −0.21 eV per H2 molecule for Sc‐, Ti‐, and V‐doped C2O systems, respectively. Storage properties under fuel‐cell operating conditions are evaluated in terms of H2 uptake and occupation number using the canonical partition function. The corresponding desorption temperature analysis further confirms the reversibility and practical viability of hydrogen storage in these systems.