Hydrogenation of Carbon Nanotubes: Roles of Symmetry and Strain

Abstract

Carbon nanotube is excellent material for hydrogen storage and molecular sensory applications thanks to its quasi-one dimensional geometry and unique structure-property relationship. In this paper, hydrogenation of carbon nanotubes is discussed in the extent of binding geometry and mechanochemical coupling under structural deformation. Our first-principles calculations show that the atomic structures, mechanical and electronic properties of carbon nanotubes can be significantly modified by hydrogenation. Moreover, the hydrogenation process is controlled by strain loading. Under an axial compressive or tensile strain of 10 %, the binding energies of hydrogen on carbon nanotubes can be changed up to -0.24 and 0.74 eV respectively. Analysis on electronic structure, mechanical properties and charge density reveals the underline mechanisms. The results reported here offer a way not only to tune the binding strength of hydrogen on carbon nanotubes in a controllable and reversible manner, but also to engineer the properties of carbon nanotubes through a synergistic control on hydrogen binding and mechanical loading.