Strain-induced switch for hydrogen storage in cobalt-decorated nitrogen-doped graphene

As a feasibility study for hydrogen storage, the adsorption behavior of H-2 on transition metal-decorated N-doped graphene is systematically investigated by density functional theory and the adsorption isotherm is used to predict to practical capacity at realistic condition by grand canonical partition function. The biaxial strain is proposed to be a reversible switch for hydrogen storage. Our computational results suggest that Co-decorated N-doped graphene is a highly promising material for hydrogen gas storage with good thermal stability and excellent gravimetric density. Additionally, the adsorption of H-2 is sensitive to the biaxial tensile strain, and the transition point of chemisorption/physisorption occurs under 8% strain. By applying 10% strain for desorption, the storage capacity can be effectively improved to 6.00 wt% (i.e. 19% enhancement) at low pressure and room temperature. Our findings not only reveal the feasibility of a tunable material for hydrogen storage, but also provide a new strategy to control the performance for hydrogen storage by biaxial tensile strain.