Exploration of Li-decorated g-C2O monolayer for enhancing hydrogen storage via first-principles calculations

Abstract

The g-C₂O monolayer, notable for its electron-rich oxygen atoms and pronounced van der Waals (vdW) forces, presents itself as a viable candidate for hydrogen storage. Through first-principles based calculations, we explore a novel composite, Li@g-C₂O, tailored for physical hydrogen adsorption. Lithium (Li) atoms are stably anchored onto the g-C₂O surface with a binding energy of −1.747 eV, ensuring thermal stability at 300 K. The system can accommodate up to eight H₂ molecules per unit cell, resulting in a total hydrogen storage capacity that exceeds the DOE target (2025). The desorption process occurs within a temperature range of 253 K–384 K, corresponding to average adsorption energy ranging from −0.152 eV/H₂ to −0.101 eV/H₂, highlighting its favorable kinetic properties for hydrogen release. The hydrogen adsorption mechanism leverages both vdW interactions and electrostatic effects, with the oxygen atoms acting as active sites. These results offer critical theoretical insights into designing high-performance hydrogen storage materials for energy applications, including sustainable transportation.