A first-principles investigation on the hydrogen storage properties of sodium-decorated graphitic carbon nitride (g-C10N3) monolayer

The global transition toward carbon-neutral energy technologies has intensified the search for safe, lightweight, and efficient hydrogen storage media capable of operating under near-ambient conditions. However, most two-dimensional materials exhibit weak interactions with H 2 , limiting their practical applicability. In this context, we investigate a Na-decorated g-C 10 N 3 monolayer (Na@g-C 10 N 3 ) engineered to overcome the intrinsically low physisorption capacity of pristine g-C 10 N 3 . First-principles calculations reveal that Na atoms bind strongly to the surface, ensuring excellent structural and thermal stability. The decorated monolayer can accommodate up to eight H 2 molecules per Na site, achieving a gravimetric capacity of approximately 7.00 wt%. Adsorption energies between −0.23 and −0.20 eV/ H 2 yield desorption temperatures of 261–299 K, enabling reversible hydrogen release near room temperature. Pressure-dependent stability analyses indicate that Na@g-C 10 N 3 remains effective for hydrogen uptake above 10 bar under ambient conditions. The favorable storage performance arises from a cooperative mechanism involving electrostatic interactions and van der Waals forces. These results demonstrate that Na@g-C 10 N 3 is a promising candidate for next-generation solid-state hydrogen storage systems.