Anomalous mechanical characteristics of graphene with tilt grain boundaries tuned by hydrogenation

Abstract

Grain boundaries (GBs) as typical defective graphene structure have significant influence on its mechanical properties. The fracture strength of hydrogenated graphene with tilt GBs composed of pentagon–heptagon defects are systematically investigated using classical Molecular Dynamics (MD) method. Anomalous mechanical characteristics are revealed for graphene with hydrogenation either on or near the GBs. For graphene sheets with hydrogenation on tilt GBs under perpendicular pulling, the strength of hydrogenated GBs with large tilt angle is anomalously stronger than low-angle tilt boundary having fewer defects because of the interaction between polar stress fields of hydrogenated pentagon–heptagon defects. For graphene with hydrogenation near the GBs, the interaction between GBs and hydrogenated domains at different distance intervals is investigated. The strength is found to be governed by the peak normal stress in hydrogenated domain, and an exponential relationship between the normal strength and distance interval is revealed as a result of the stress field overlap between GB and hydrogenation interface. Our results gain meaningful insight into the effects of hydrogenation on the strength of graphene with tilt GBs, and provide guidelines for designing high-quality hydrogenated graphene-based nanodevices.