Mechanical properties of graphene under molecular hydrogen physisorption: An ab initio study

This paper investigates the mechanical properties of graphene subjected to adsorption of molecular hydrogen through an ab initio approach. First, using density functional theory (DFT) with both generalized gradient and local density approximation functionals, the most stable configuration for physisorption of molecular hydrogen on the graphene is determined. All possible adsorption sites are considered, and it is revealed that the most stable state happens above the center of a hexagon with the equilibrium distance of 2.7 Å when the axis of the hydrogen molecule is parallel to the graphene surface. Thereafter, DFT calculations are performed to obtain the in-plane stiffness and Poisson’s ratio of graphene under the above-mentioned adsorption position. It is found that the effect of hydrogen physisorption on the mechanical properties of graphene is not very significant.