High thermal conductivity of free-standing skeleton in graphene foam

Due to the high-porosity structure, the low thermal transport property of graphene foam (GF) is expected. However, the interconnected skeleton can still act as excellent thermal conductor branches if phonon scattering is not severely affected in the structure of graphene flakes. Such a property has not been validated experimentally due to the difficulty in sample manipulation and the fragility of the structure. In this work, we report the characterization results of thermal properties of the free-standing skeleton in GF. Three individual skeleton samples from one GF piece are prepared under the same condition. The thermal diffusivity of GF skeletons is characterized in the range of 3.26–3.48 × 10−4 m2/s, and the thermal conductivity is determined to be 520–555 W/(m K), which is two orders of magnitude larger than the value of bulk GF. These high thermal conductivity values originate from the intrinsic thermal property of graphene, while the contact interfaces, wrinkled structures, and defects induced in the synthesis process do not affect the phonon transport property significantly, which proves that the three-dimensional hierarchical graphene structure can still be implemented in energy-intensive applications.