Enhanced Hydrogen Storage Capacity in OLi₃-Decorated Holey Graphitic Carbon Nitride Monolayer

The primary challenge hindering the widespread adoption of hydrogen energy is its storage, highlighting the need for effective storage media. In this study, we utilize first-principles calculations to systematically evaluate the superalkali cluster OLi₃ decorated on a CN monolayer for its potential as an efficient hydrogen storage material. Our findings reveal that the OLi₃ cluster binds to each side of the CN monolayer through a charge transfer mechanism, exhibiting a binding energy of 12.32 eV per OLi₃. The OLi₃ cluster, when integrated into the OLi₃-decorated CN monolayer, displays a loss of charge, thereby creating a localized electric field around the cluster. This phenomenon facilitates the polarized hydrogen adsorption process through a combination of orbital interactions, electrostatic interactions, and van der Waals forces. The maximum number of hydrogen molecules that can be adsorbed by the 2(OLi₃)-decorated CN monolayer is 12. The average adsorption energy per hydrogen molecule is 0.185 eV, with a gravimetric density of 9.45 wt %, significantly exceeding the target set by the U.S. Department of Energy (6.5 wt %). Additionally, the effects of the temperature and pressure on hydrogen storage performance indicate that the hydrogen-adsorbed structures of the OLi₃-decorated CN monolayer remain stable at room temperature under mild pressure. These results suggest that the OLi₃-decorated CN monolayer may serve as a promising material for reversible hydrogen storage.