N-graphdiyne as a tunable platform for stabilizing light metals toward high-capacity reversible hydrogen storage

Hydrogen (H 2 ) is a promising carbon–neutral energy carrier; however, its deployment is limited by the lack of lightweight, reversible storage media that operate under practical conditions. Here, we establish nitrogen-doped graphdiyne (N-GDY) as a programmable two-dimensional (2D) platform for stabilizing dispersed light-metal dopants and enabling high-capacity molecular H 2 physisorption. The computational package involves density functional theory (DFT) combined with ab initio molecular dynamics (AIMD) and Langmuir‑based statistical thermodynamic modeling. The results revealed that N‑sites of N-GDY bind up to five Li, Na, K, and Ca atoms per primitive cell with binding energies of − 2.27, −1.57, −1.80, and − 2.13 eV, respectively, exceeding their respective bulk cohesive energies. AIMD simulations for 10 picoseconds at 400 K further confirm the structural robustness of the decorated frameworks without observing any evidence of metal aggregation. The polarised metal centres activate reversible H 2 adsorption through electrostatic and dispersion interactions, with average adsorption energies falling within the optimal window (−0.15 to −0.35 eV per H 2 ). Sequential adsorption analysis reveals uptake of up to 25 H 2 molecules per primitive cell, achieving intrinsic gravimetric capacities of 13.08, 10.82, 9.23, and 9.15 wt% for Li-, Na-, K-, and Ca-functionalized systems, respectively. Thermodynamic analysis indicates favorable adsorption–desorption behavior under near-ambient conditions, with Li- and Ca-functionalized systems exceeding the 6.5 wt% U.S. Department of Energy’s ultimate system-level target when considering intrinsic material capacity. These results identify N-GDY as a chemically tunable scaffold for dispersing lightweight metals and provide a mechanistic design strategy for achieving high-capacity, reversible hydrogen storage in porous 2D materials.