Preparation and structure analysis of expanded graphite-based composites made by phosphoric acid activation

A new kind of expanded graphite-based composites (EGC) was prepared by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. It involves expanded graphite (EG), sucrose and phosphoric acid as starting materials. X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption and mercury porosimetry were selected to analyze the microstructure of the EGC. The results showed that the EGC were made up of graphite and activated carbon. The EGC was not the simply mechanical mixture of the EG and the activated carbon, but coating the activated carbon on the surface of interior and external pores of the EG in the form of thin carbon layer. The thickness of the activated carbon layer was nearly 100 nm by calculation. So the prepared EGC consisted of both macropores from EG and micropores from activated carbon.