Computational study on thermal conductivity of defective carbon nanomaterials: carbon nanotubes versus graphene nanoribbons

Carbon-based nanostructures possess exceptional thermal properties and are being intensively explored as thermal management materials. In this paper, the thermal conductivities of carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) with vacancy defects are compared by using non-equilibrium molecular dynamics simulations. The results show that the vacancy defects markedly decrease the thermal conductivities of CNTs and GNRs. By analyzing the vibrational density of states and contributions of lattice vibrations, we demonstrate that the lower thermal conductivities of defective CNTs and GNRs are attributed to the depressions of longitudinal acoustic and transverse acoustic modes, respectively. In the temperature range of 200–600 K, the vacancies always have a weaker effect on heat transfer of GNR than that of CNT, which stems from the mode localization induced by the phonon scattering on GNR edges. In addition, the percentage change in thermal conductivity of CNT decreases with increasing temperature, while that of GNR is generally independent of temperature. This phenomenon is related to the sensitivity of lattice vibration contributions to temperature. The present work expands our understanding of vacancy effect on heat conduction in carbon-based nanostructures.