Low-cost synthesis of high quality graphene oxide with large electrical and thermal conductivities

A simple and cost-effective method for synthesizing high quality thermally reduced graphene oxide (TrGO) thin films using Shellac, is presented. The synthesis temperature ranges from 550 degrees C to 900 degrees C, and is the sole control parameter to obtain a carbon content as high as 97 atomic percentage. For TrGO synthesized at 900 degrees C, its XPS, Raman, and TEM data indicate a large portion of sp(2) hybridized carbon atoms and large crystal sizes (similar to 1 mu m), which resulted in very high electrical and cross-plane thermal conductivities, 2488 S/cm and 1.3 W/m-K, respectively. Furthermore, this high electrical conductivity of TrGO was observed to remain unaffected under mechanical stress 10 times higher than that completely broke solution-processed reduced graphene oxide (rGO) films, promising its potential for robust, transparent, and cost-effective conductive coating. (C) 2021 Elsevier B.V. All rights reserved