Comparison in Factors Affecting Electrochemical Properties of Thermal-Reduced Graphene Oxide for Supercapacitors

Abstract

In this paper, thermal-reduced graphene oxide(T-RGO) materials are synthesized by modified Hummer's method,followed by thermal reduction under argon atmosphere at different temperatures. Electrochemical investigations show that, for T-RGO electrodes, good electrical conductivity is necessary and the surface functional groups play more significant role than the specific surface area in determining the electrochemical capacitance. The T-RGO obtained at 900oC(T-RGO900) with a relatively high Brunauer-Emmett-Teller(BET) surface area(314 m2·g-1) and a high electrical conductivity(2421 S·m-1) shows a low specific capacitance of 56 F·g-1. In comparison, the T-RGO obtained at 300oC(T-RGO300) with a relatively low BET surface area(18.8 m2·g-1)and an electrical conductivity(574 S·m-1) provides the largest specific capacitance of 281 F·g-1. The large specific capacitance of T-RGO300 results from the simultaneous contributions of the electrochemical double-layer capacitance and the pseudo-capacitance obtained from the oxygenated groups on the T-RGO surfaces. Therefore, it probably gives a new insight for designing and synthesizing graphene-based electrode materials for supercapacitors and other energy-storage devices.