A molecular dynamics study of the mechanical properties of hydrogen functionalized graphene

Molecular dynamics simulations have been performed to investigate the mechanical properties of hydrogen functionalized graphene for H-coverages spanning the entire range from graphene (H-0%) to graphane (H-100%). We find that the Young’s modulus, tensile strength, and fracture strain of the functionalized graphene deteriorate drastically with increasing H-coverage up to about 30%. Beyond this limit the mechanical properties remain insensitive to H-coverage. While the Young’s modulus of graphane is smaller than that of graphene by 30%, the tensile strength and fracture strain show a much larger drop of about 65%. We show that this drastic deterioration in mechanical strength arises both from the conversion of sp2 to sp3 bonding and due to easy-rotation of unsupported sp3 bonds. Our results suggest that the coverage-dependent deterioration of the mechanical properties must be taken into account when analyzing the performance characteristics of nanodevices fabricated from functionalized graphene sheets.