Reversible Hydrogen Storage Properties of Superalkali NLi ₄ -Decorated Inorganic Graphenylene SiC

Hydrogen energy has the potential to substitute for fossil-based energy; however, the primary challenge is its effective storage materials. Taking this into consideration, utilizing the quantum chemical methods, superalkali NLi₄-decorated inorganic graphenylene SiC (IGP-SiC) has been investigated to explore the reversible hydrogen storage at the GGA-PBE level. The binding energy of NLi₄ on the top of the hexagonal ring of IGP-SiC is observed to be -4.89 eV. NLi₄ binds strongly to the IGP-SiC monolayer via electronic charge redistribution, leading to the creation of a positive charge on Li atoms, which facilitates the adsorption of H₂ through orbital interactions and van der Waals forces. The 3NLi₄@IGP-SiC adduct can adsorb up to 45H₂, resulting in a gravimetric density of 7.69 wt % (surpassing the DOE target of 5.5 wt %) with an average adsorption energy of -0.196 eV/H₂. Using the van't Hoff equation, the desorption temperature is calculated to be 305 and 345 K at 5 and 12 atm pressure, respectively. Ab initio molecular dynamics (AIMD) simulation has been conducted at 300 K to check the thermal stability and reversibility of H₂ adsorption. Additionally, the climbing-image nudged band elastic (CI-NEB) method shows a hydrogen desorption energy barrier of 0.121 eV. These findings suggest that NLi₄-decorated IGP-SiC may serve as a promising reversible hydrogen storage material for future use as per the DOE guidelines.