Strain engineering on graphene towards tunable and reversible hydrogenation

TL;DR

This study demonstrates how mechanical strain can be used to reversibly control hydrogen binding on graphene, enabling tunable hydrogenation and property engineering for advanced applications.

Contribution

It reveals the effects of strain on hydrogen binding energies and electronic properties of graphene, proposing a reversible hydrogen storage method based on mechanical deformation.

Findings

Hydrogen binding energies increase significantly under strain.

Reversible hydrogen storage is possible through mechanical deformation.

Strain modifies graphene's electronic structure and stability.

Abstract

Graphene is the extreme material for molecular sensory and hydrogen storage applications because of its two-dimensional geometry and unique structure-property relationship. In this Letter, hydrogenation of graphene is discussed in the extent of intercoupling between mechanical deformation and electronic configuration. Our first principles calculation reveals that the atomic structures, binding energies, mechanical and electronic properties of graphene are significantly modified by the hydrogenation and applied strain. Under an in-plane strain of 10 %, the binding energies of hydrogen on graphene can be improved by 53.89 % and 23.56 % in the symmetric and anti-symmetric phase respectively. Furthermore the instability of symmetrically bound hydrogen atoms under compression suggests a reversible storage approach of hydrogen. In the anti-symmetric phase, the binding of hydrogen breaks the sp2 characteristic of graphene, which can be partly recovered at tensile strain. A charge density based analysis unveils the underline mechanisms. The results reported here offer a way not only to tune the binding of hydrogen on graphene in a controllable and reversible manner, but also to engineer the properties of graphene through a synergistic control through mechanical loads and hydrogen doping.