Superalkali OLi3 anchored biphenylene for hydrogen storage: Acumen from first-principles study

Developing efficient hydrogen storage materials is critical for reducing reliance on conventional fossil fuels in the transportation sector. In this context, we employed first-principles calculations to explore the hydrogen storage potential of biphenylene (BPN) sheets with superalkali OLi3 clusters. With both side coverage, the anchoring of OLi3 clusters to the BPN sheet occurs via a charge transfer mechanism, resulting in strong binding with a calculated binding energy of −3.05 eV per OLi3 cluster. The OLi3 anchored clusters significantly enhances the potential by generating additional active sites, thereby improving H2 adsorption through a combined electrostatic and van der Waals interaction mechanism. In the 2OLi3/BPN complex, up to 18 H2 molecules can be effectively adsorbed, with adsorption energies ranging from −0.217 to −0.282 eV, yielding a remarkable gravimetric hydrogen density of 9.11 wt%. This value surpasses the U.S. Department of Energy's benchmark for hydrogen storage, set at 5.5 wt%. Using the van't Hoff equation, the desorption temperature of the 2OLi3/BPN+18H2 complex is calculated to be 258 K at 1 atm and 337 K at 5 atm, indicating favorable hydrogen release characteristics. Furthermore, ab initio molecular dynamics simulations confirm both the structural stability of the material and the reversibility of H2 adsorption. With the appropriate H2 adsorption energy, high gravimetric density, and structural stability, it is expected that the use of OLi3 anchored BPN sheets will serve as an effective method with high-capacity reversible hydrogen storage. © 2024 Elsevier Ltd