The electrocatalytic performance and pseudocapacitive characteristics of a modified graphite electrode（MGE）with Fe 3＋ /Fe 2＋ in H 2 SO 4 solution were studied by cyclic voltammetry（CV）,constant current charge-discharge measurements,and electrochemical impedance spectroscopy（EIS）.The results showed that the MGE had high electrocatalytic activity and good reversible characteristics for the redox reaction of Fe 3＋ /Fe 2＋ because of a large quantity of oxygen-containing functional groups on the MGE surface.The apparent area-specific capacitance of the MGE in 2.0 mol·L -1 H 2 SO 4 solution containing 0.5 mol·L -1 Fe 3＋ and 0.5 mo·lL -1 Fe 2＋ reached 2.157 F·cm -2 ,which was almost double that in 2.0 mo·lL -1 H 2 SO 4 without Fe 3＋ / Fe 2＋ .Meanwhile,increasing the concentration of iron ions increased the capacitance of the MGE.The addition of Fe 3＋ /Fe 2＋ made the charge-discharge curves more symmetric and change more slowly,which increases the charge-discharge time,and effectively improves the capacitive energy storage and high power performance for an electrochemical capacitor（EC）.The obvious capacitive characteristics were confirmed by EIS,and are attributed to the oxygen-containing functional groups on the MGE and the Faraday redox reaction of Fe 3＋ /Fe 2＋ in the thin electrolyte layer.Therefore,the oxygen-containing functional groups on the MGE surface and redox reaction of Fe 3＋ /Fe 2＋ can be used together for energy storage and release.
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