Thermal rectification in ultra-narrow hydrogen functionalized graphene: a non-equilibrium molecular dynamics study

In this study, the non-equilibrium molecular dynamics simulation (NEMD) has been used to evaluate the thermal properties, especially the rectification of ultra-narrow edge-functionalized graphene with hydrogen atoms. The system's small width equals 4.91 Å (equivalent to two hexagonal rings). The dependence of the thermal rectification on the mean temperature, hydrogen concentration, and temperature difference between the two baths was investigated. Results reveal that the thermal rectification increases to 100% at 550 K by increasing the mean temperature. Also, it is disclosed that hydrogen concentration plays a vibrant role in thermal rectification. As a result of maximum phonon scattering at the interface, a thorough rectification is obtained in a half-fully hydrogenated system. As well, the effects of temperature difference of baths ΔT on thermal rectification has been calculated. As a result, the thermal rectification decreases even though the current heat increases with ΔT. Finally, the thermal resistance at the interface using a mismatching factor between the two-phonon density of states (DOS) on both sides of the interface has been explained.