First experimental study of freestanding graphene foam skeleton
DOI: 10.1063/10.0003190
First experimental study of freestanding graphene foam skeleton lead image
Graphene, a popular 2D material, has superior thermal properties. However, an integrated form known as graphene foam (GF), used in nanocomposite materials, has low thermal conductivity because of its porous structure.
A rigid portion of GF, known as the skeleton, forms the pores. The skeleton is thought to act as an efficient heat dissipation network. However, its fragility has made direct characterization of thermal properties difficult.
Gao et al. report the first experimental investigation of a freestanding GF skeleton. Thermal properties were measured to determine if the skeleton could provide an effective heat dissipation network in the foam.
The GF sample had been commercially synthesized by conventional chemical vapor deposition. The resulting complex foam structure had an average pore size of about 200 microns. Raman and SEM characterization confirmed the skeleton is covered with a network of graphene flakes that create a fluctuating surface on the GF skeleton consisting of wrinkled structures.
“In order to characterize the thermal properties of a free-standing GF skeleton, it is necessary to separate it from the bulk foam structure. The skeleton is extremely fragile, and we have failed many times in sample preparation” said author Yanan Yue. To this end, the investigators carefully separated GF skeletons from the foam and then glued them to electrodes.
“Previously, people could only characterize overall thermal properties of GF, and the thermal property of the skeleton was an estimated value,” said Yue. “Our work is the first to validate that the skeleton can act as an excellent thermal conductor inside the foam.”
Further measurements showed phonon propagation dominates thermal transport in the GF skeleton. A significant role is played by phonon scattering from the wrinkled structures.
Source: “High thermal conductivity of free-standing skeleton in graphene foam,” by Jianshu Gao, Danmei Xie, Xinwei Wang, Xin Zhang, and Yanan Yue, Applied Physics Letters (2020) The article can be accessed at https://doi.org/10.1063/5.0032408 .
