Exploring the Impact of Electric Field and OLi₃ Decoration on Inorganic Graphenylene SiC for Reversible Hydrogen...

The hydrogen storage capacity of superalkali OLi₃-decorated inorganic graphenylene SiC (IGP-SiC) has been explored using first-principles calculations employing the GGA-PBE functional. Notably, OLi₃ is found to be strongly bonded to the IGP-SiC monolayer with a binding energy of -3.89 eV. Thus, a positive charge is developed on the lithium atom of OLi₃ due to charge redistribution, which enhances its hydrogen adsorption energy. The interaction of H₂ with OLi₃@IGP-SiC involves charge polarization as well as orbital and van der Waals interactions. Our calculations reveal a remarkable hydrogen storage capacity of 10.93 wt %, surpassing the DOE-recommended limit of 6.5 wt %, where the hydrogen adsorption energy is found to be in the range of -0.19 to -0.15 eV/H₂. To assess the thermal stability and reversibility of hydrogen storage exhibited by OLi₃@IGP-SiC, ab initio molecular dynamics (AIMD) simulations were performed at temperatures of 100, 200, and 300 K. Hydrogen adsorption energy (E _H2 ^ad) of OLi₃@IGP-SiC can be tuned by applying an electric field. It is noticed that E _H2 ^ad in OLi₃@IGP-SiC + 1H₂ is increased from -0.197 eV/H₂ (at zero electric field) to -0.657 eV/H₂ upon application of a +0.055 V/Å electric field. Furthermore, by employing the climbing-image nudged elastic band method, the hydrogen diffusion energy barrier is found to be 0.054 eV. Therefore, the OLi₃-decorated IGP-SiC monolayer designed in this study may serve as a potential reversible hydrogen storage material.