High-capacity hydrogen storage in yttrium-decorated ψ-graphene: Acumen from density functional theory

Employing density functional theory simulations, we have predicted Y-decorated psi-graphene as a potential hydrogen storage material for fuel cell vehicle (FCV) applications. The system is stable at ambient and higher temperatures as substantiated by ab initio molecular dynamics simulations and is capable of holding 8.31 wt. % of hydrogen, higher than the U.S. Department of Energy (DOE) target. Each Y atom attached on psi-graphene can adsorb seven H-2 molecules with a mean binding energy of -0.39 eV per H-2 and a desorption temperature of 496.55 K-highly suitable for fuel cell applications. The Y atom binds strongly with the psi-graphene sheet, evident from the binding energy of -3.06 eV. The presence of a diffusion energy barrier of 0.4-0.7 eV for the diffusion of Y atom across psi-graphene may prevent metal-metal clustering. The flow of charge is found to be from Y atom 4d orbitals toward the C 2p orbitals of psi-graphene. Hydrogen molecules are found to bind reversibly by Kubas interactions involving charge donation and back donation between Y atom 4d orbitals and 1s orbitals of hydrogen, allowing for a suitable binding energy for FCV applications. Considering the stability of the system, optimum binding energy, and desorption temperature as per U.S. DOE targets; adequate barrier energy for diffusion; and excellent gravimetric hydrogen storage capability of the material, we propose Y-decorated psi-graphene as a potent hydrogen storage material for FCV applications. Published under an exclusive license by AIP Publishing.

Automated summary

The study predicts Y-decorated psi-graphene as a potential hydrogen storage material for fuel cell vehicle applications. The material exhibits stability at ambient and higher temperatures, with a high hydrogen storage capacity and suitable binding energy. The research also reveals the diffusion behavior of Y atom on psi-graphene, as well as the charge transfer mechanism between Y atoms and hydrogen molecules. Based on the excellent gravimetric hydrogen storage capability, the study proposes Y-decorated psi-graphene as a promising material for FCV applications.