Thermal transport in graphene fiber fabricated by wet-spinning method

•The thermal diffusivity of the suspended graphene fiber sample was measured.•The intrinsic thermal conductivity was 1.14–1.18 W/m K.•The thermal contact resistance was the main reason for the low thermal conductivity.

Graphene-based materials are usually expected to be good thermal conductors. Here, we report on the low thermal diffusivity of free-standing graphene fibers (GFs) fabricated by wet-spinning method. The GF sample mainly consists of freestanding graphene oxide. The radiation effect is excluded by measuring GFs of different lengths. The thermal diffusivity of the suspended GF sample is determined at (2.0–2.08)×10−6 m2 s−1, and the corresponding intrinsic thermal conductivity is 1.14–1.18 W/m K. The low thermal conductivity is mainly attributed to the large thermal contact resistance and very strong phonon scattering at grain boundaries. The finding will be beneficial for thermal design of GF-based thermal energy applications.