Tailoring thermal conductivity of bulk graphene oxide by tuning the oxidation degree

Bulk graphene oxide (GO) shows great potential in a variety of applications, such as sensors, photodetectors, supercapacitors, lithium ion batteries and catalysts. However, its thermal conductivity, one of the most important and fundamental physical properties, is still less known. Herein, we have systematically investigated the thermal conductivity of bulk GOs and find that it can be tailored by tuning their oxidation degree during preparation process. Notably, the cross-plane thermal conductivity of bulk GO, in comparison with its precursor graphite, exhibits more than 100 times decrease at room temperature. The dependence of thermal conductivity of GO on oxidation degree is attributed to the chemical and structural changes by introducing oxygen atoms and oxygen-containing functional groups, which can lead to a significant enhancement in atomic- and nano-scale phonon scattering. Furthermore, we reveal that the thermal conductivity of bulk GOs exhibits evident anisotropic behavior. These results provide fundamental understanding and valuable information on thermal transport properties of bulk GOs for various practical applications.