Enhancing Hydrogen Storage in Carbon‐Substituted Beryllium Nitride: A DFT ‐Based Investigation

ABSTRACT Density functional theory (DFT) is used to evaluate the hydrogen storage properties of C‐substituted BeN 4 , a stable and lightweight beryllium nitride monolayer. The C‐substituted BeN 4 monolayer adsorbs up to 18 H 2 molecules with an average adsorption energy of −0.24 eV/H 2 . Carbon substitution improves structural integrity and hydrogen uptake, in contrast to conventional metal doping, which often compromises material stability. Charge transfer occurs during the hydrogen adsorption process, with carbon and hydrogen gaining charge while nitrogen loses charge. This enhanced charge transfer, enabled by the reduced electronegativity of carbon compared to pristine BeN 4 , results in improved adsorption energy. Reduced density gradient (RDG) analysis reveals that weak van der Waals interactions between H 2 molecules and the C‐BeN 4 substrate dominate the adsorption mechanism. Ab initio molecular dynamics (AIMD) simulations confirm the thermal robustness of C‐BeN 4 with nine substituted carbon atoms. The corresponding desorption temperature is 308 K. With nine carbon substitutions, the hydrogen uptake reaches 6.02 wt%, in accordance with the U.S. DOE target. Owing to its high hydrogen adsorption capacity, favorable desorption temperature, and structural stability, C‐substituted BeN 4 emerges as a promising candidate for hydrogen storage applications. These theoretical findings provide strong motivation for the development of hydrogen storage devices based on C‐BeN 4 .