Carbon structure and the resulting graphitizability upon oxygen evolution

Abstract

Model compoundsanthracene, sucrose, anthanthrone, anthrone and fluorene were carbonized at 500 °C and subsequently heat treated at 2600 °C. The majority of initial oxygen content was lost during low temperature carbonization. The intermediate species formed after oxygen evolution dictated the resulting carbon skeleton and thus the graphitizability. Anthracene and sucrose were selected as model graphitizing and non-graphitizing compounds based on historical precedence. Carbonization of anthanthrone resulted in a graphitizable coke, whereas anthrone yielded a non-graphitizable char. It is proposed that CO loss from anthanthrone results in the formation of perylene, where CO loss from anthrone produces fluorene. An obvious resemblance was observed in structure between heat treated sucrose and anthrone char as compared to heated treated char embedded with 5 membered rings via carbonization of fluorene. Thus, providing evidence that 5 membered rings are present in the virgin chars and are the cause of non-graphitizability. Polarized light microscopy was employed to measure the extent of mesophase development after carbonization. Transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and electron energy loss spectroscopy were used to characterize the material before and after annealing.