▎ 摘　　要

The sustainable synthesis of high-quality graphene sheets is one of the hottest and most inspiring topics in the fields of science and engineering. While the graphene oxide (GO) chemical reduction method is widely used to synthesize graphene sheets, this route commonly includes highly hazardous reducing agents that are dangerous to both humans and the environment. In this context, here we describe a green, effective, and economical strategy for the synthesis of soluble graphene by using a Eucalyptus polyphenol solution that is obtained from a Eucalyptus bark extract. The reducing ability of polyphenol compounds present in the Eucalyptus bark extract is responsible for the reduction of exfoliated GO to soluble graphene under reflux conditions in an aqueous medium. The XRD, FT-IR, XPS, and UV-vis results demonstrate the effective removal of the oxygen functionalities in GO. TEM and AFM images show straight corroboration for the development of 1-4 layers of graphene. The stable and homogeneous dispersion of the E-graphene in various solvents, both aqueous and nonaqueous, confirms the powerful interactions between Eucalyptus polyphenol compounds and graphene. The electrochemical performances are evaluated by cyclic voltametry (CV) and galvanostatic charge-discharge (GCD). GCD results show that the E-graphene supercapacitor has a high specific capacitance of 239 F g(-1) and a high energy density of 71 W h kg(-1) at a current density of 2 A g(-1). These characteristics demonstrate that this green approach has an excellent prospective not only in the fabrication of high-performance supercapacitors but also in the synthesis of graphene-based materials.