Systematic characterization of transport and thermoelectric properties of a macroscopic graphene fiber

Graphene, a two-dimensional material with extraordinary electrical, thermal, and elastic performance, is a potential candidate for future technologies. However, the superior properties of graphene have not yet been realized for graphenederived macroscopic structures such as graphene fibers. In this study, we systematically investigated the temperature (T)-dependent transport and thermoelectric properties of graphene fiber, including the thermal conductivity (lambda), electrical conductivity (sigma), and Seebeck coefficient (S). lambda increases from 45.8 to 149.7 W center dot m(-1)center dot K-1 and then decreases as T increases from 80 to 290 K, indicating the boundary-scattering and three-phonon Umklapp scattering processes. sigma increases with T from 7.1 x 10(4) to 1.18 x 10(5) S center dot m(-1), which can be best explained by the hopping mechanism. S ranges from-3.9 to 0.8 mu V center dot K-1 and undergoes a sign transition at approximately 100 K.