氧化还原
循环伏安法
介电谱
半反应
X射线光电子能谱
化学
电化学
无机化学
石墨
傅里叶变换红外光谱
滴定法
电极
材料科学
分析化学(期刊)
化学工程
有机化学
物理化学
工程类
作者
Xinzhuang Fan,Yonghong Lu,Hongyao Xu,Xiangfeng Kong,Jia Wang
摘要
Reversible redox reactions on the oxygen-containing functional groups of an electrochemically modified graphite electrode (GE) by recurrent galvanic pulses in 2.3 M H2SO4 solution are investigated. The crystal morphology, surface composition and electrochemical performance of electrochemically modified GE are monitored by scanning electron microscopy, Raman spectroscopy, nitrogen adsorption, Fourier transform infrared spectroscopy, thermogravimetry, Boehm's titration, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry (CV) tests. After the electrochemical modification, the material shows a turbostratic structure with many small domains consisting of multi-layered graphene sheets in parallel, and presents a high specific capacitance of 179.7 F g−1, as well as a good stability after 10000 CV cycles. The high specific capacitance is mainly attributed to the continuous reversible redox reactions of the active groups among the hydroxyl (reduced state), carbonyl (half-oxidized state) and carboxyl (fully oxidized state) groups; a redox mechanism is obtained consequently. The amount of active groups on the modified GE surface is about 848–875 μmol g−1 by the Boehm titration. Their contribution to the pseudo-capacitance according to the redox mechanism is about 130–140 F g−1, which is consistent with the results of electrochemical measurements.
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