Hydrogen storage in Sc-decorated Ψ-graphene via density functional theory simulations

Abstract

Efficient methods and materials to store hydrogen onboard in light-duty fuel cell vehicles is crucial to move away from fossil fuels in the transport sector. Metal-decorated carbon materials are considered as promising materials for hydrogen storage. In this regard, using density functional theory (DFT) simulations incorporating the generalized gradient approximation functional along with the DFT-D2 dispersion correction scheme, we predict that Sc-decorated Ψ-graphene is a promising hydrogen storage material. The Sc atom binds strongly to Ψ-graphene (binding energy ∼3.02 eV), and binds seven H2, with an average binding energy of −0.36 eV/H2 and desorption temperature of ∼400 K. The hydrogen storage capacity with five and seven H2 is 8.59 and 14.46 wt%, respectively, which achieves the requirements of the U. S. Department of Energy for an efficient, onboard and reversible hydrogen storage material in light fuel cell vehicles. The system is stable at room temperature, as verified by ab initio molecular dynamics simulations. The likelihood of Sc–Sc clustering is low due to the high diffusion energy barrier of Sc over the Ψ-graphene surface. Thus, we predict that Sc-doped Ψ-graphene is an excellent reversible hydrogen storage material.