材料期刊网

The electrocatalytic performance and pseudocapacitive characteristics of a modified graphite electrode (MGE) with Fe3+/Fe2+ in H2SO4 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 Fe3+/Fe2+ 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 H2SO4 solution containing 0.5 mol.L-1 Fe3+ and 0.5 mol.L-1 Fe reached 2.157 F.cm(-2), which was almost double that in 2.0 mol.L-1 H2SO4 without Fe3+/Fe2+. Meanwhile, increasing the concentration of iron ions increased the capacitance of the MGE. The addition of Fe3+/Fe2+ 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 Fe3+/Fe2+ in the thin electrolyte layer. Therefore, the oxygen-containing functional groups on the MGE surface and redox reaction of Fe3+/Fe2+ can be used together for energy storage and release.