Thermal conductivity of graphene kirigami: Ultralow and strain robustness

Kirigami structure, from the macro- to the nanoscale, exhibits distinct and tunable properties from original two-dimensional sheet by tailoring the original two-dimensional sheet. In the present work, the extreme reduction of the thermal conductivity by tailoring sizes in graphene nanoribbon kirigami (GNR-k) is demonstrated using nonequilibrium molecular dynamics simulations. The results show that the thermal conductivity of GNR-k (around 5.1 W m−1K−1) is around two orders of magnitude lower than that of the pristine graphene nanoribbon (GNR) (around 151.6 W m−1K−1), while the minimum value is expected to be up to zero in extreme case from our theoretical model. The further study of the micro-heat flux on each atom of GNR-k shows the reduction of the thermal conductivity from three main sources: the elongation of real heat flux path, the overestimation of real heat flux area and the phonon scattering at the vacancy of the edge. In particular, the strain engineering effect on the thermal conductivity of GNR-k and a thermal robustness property has been investigated. Our results provide physical insights into the origins of the ultralow and robust thermal conductivity of GNR-k, which also suggests that the GNR-k can be used for nanoscale heat management and thermoelectric application.