Thermal transport properties of defective graphene: A molecular dynamics investigation

In this work the thermal transport properties of graphene nanoribbons with randomly distributed vacancy defects are investigated by the reverse non-equilibrium molecular dynamics method. We find that the thermal conductivity of the graphene nanoribbons decreases as the defect coverage increases and is saturated in a high defect ratio range. Further analysis reveals a strong mismatch in the phonon spectrum between the unsaturated carbon atoms in 2-fold coordination around the defects and the saturated carbon atoms in 3-fold coordination, which induces high interfacial thermal resistance in defective graphene and suppresses the thermal conductivity. The defects induce a complicated bonding transform from sp(2) to hybrid sp-sp(2) network and trigger vibration mode density redistribution, by which the phonon spectrum conversion and strong phonon scattering at defect sites are explained. These results shed new light on the understanding of the thermal transport behavior of graphene-based nanomaterials with new structural configurations and pave the way for future designs of thermal management phononic devices.