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应用循环伏安、极化曲线和交流阻抗等电化学方法研究了V(Ⅳ)/V(Ⅴ)电对在石墨毡复合电极上反应的速控步骤.结果表明,V(Ⅳ)/V(Ⅴ)电对在石墨毡电极上的反应属准可逆过程,且氧化过程包含有后置化学转化步骤;该过程Tafel斜率的实验值为0.124,而理论计算的,以电化学步骤作为控制步骤的Tafel斜率约0.12,两者吻合很好,表明该氧化过程受电化学步骤控制;以等效电路拟合不同极化电位下的交流阻抗,得出该电化学反应阻抗远大于其他阻抗,意味着电化学过程可能是电极反应的控制步骤,与实验得到的极化曲线分析结果相一致.
The electrochemical reaction of V (Ⅳ) / V (V) on graphite felt electrode was investigated by cyclic voltammetry, polarization curve and electrochemical impedance spectroscopy. The results showed that V (Ⅳ) / V Ⅴ) Electron pair reaction on the graphite felt electrode quasi-reversible process, and the oxidation process includes a post-chemical conversion step; the experimental Tafel slope of the experimental value of 0.124, while the theoretical calculation, the electrochemical step as a control step Tafel slope of about 0.12, the two agree well, indicating that the oxidation process is controlled by the electrochemical steps; Equivalent circuit fitting polarization impedance of different AC impedance obtained that the electrochemical impedance is much larger than other impedances, meaning The electrochemical process may be the control step of the electrode reaction, consistent with the experimental polarization curve analysis.