Effects of the tensile strain on absorption and diffusion of hydrogen atoms on graphene were studied by first-principles calculations. The calculations suggested that there existed a barrier of 0.22eV for H atom to diffuse from free space to graphene. The barrier originates from the transition of the hybridization of the H-bonded carbon atom in graphene from sp2 to sp3, and was robust against the tensile strain. It was also found that, first, the in-plane diffusion of H atoms on graphene was unlikely to happen at low temperature due to the high barrier without or with strain, and second, the tensile strain along the armchair direction greatly decreased the out-plane diffusion barrier of H atoms, making it possible at low temperature. In particular, when the armchair strain was moderate, it was found that the out-plane diffusion of H atoms likely to happen by diffusing through C-C bonds, and for relatively large armchair strain, the out-plane diffusion will happen though the center of the benzene ring.

Manipulating Absorption and Diffusion of H Atom on Graphene by Mechanical Strain. Yang, M., Nurbawono, A., Zhang, C., Wu, R., Feng, Y., Ariando: AIP Advances, 2011, 1[3], 032109