Green Synthesis of Graphene from Graphite in Molten Salt Medium

Abstract

Green synthesis of graphene from graphite was carried out in molten salt mixture of LiCl-KCl, which is an environmentally friendly alternative to traditional methods using a large number of chemicals. The effect of carbonization temperature on the final properties of graphene products was investigated at a temperature range of 500-800°C. The layer numbers of graphene products were determined as a single layer and few layers by XRD and Raman analyses. The highest conductivity value of 1219 S/m was reached with the sample synthesized at 600°C (GGr600), which is 10-fold higher than that of commercial graphene (CG) (115 S/m). The percentage of carbon contents of GGr600 and sample synthesized at 800°C (GGr800) was determined as 86% and 73% by XPS. From the SEM analyses, it was observed that graphene products have sheet-like structures. A TEM image showed that GGr800 has the thickness changing from 5-9 nm, pointing out the graphene with few layers. AFM analysis demonstrated that GGr600 has a single-layer sheet-like structure.