热处理碳纸电极上VO2+/VO+2氧化还原动力学

在不同温度下热氧化处理碳纸, 用循环伏安、极化曲线和交流阻抗方法研究碳纸电极上VO2+/VO+2氧化还原动力学. 循环伏安和极化曲线结果表明, 随着热处理温度的升高, VO2+/VO+2氧化还原反应的速率常数及交换电流增大. 建立了VO2+/VO+2氧化还原反应的交流阻抗等效电路模型. 拟合结果表明, 热处理增大了碳纸电极表面的双电层电容, 减小了VO2+/VO+2氧化还原反应的电荷转移电阻. 用循环伏安和交流阻抗两种方法求得的VO2+和VO+2的扩散系数基本相同, 表明所构建的交流阻抗等效电路模型与电极反应过程相符合.

Kinetics of the VO2+/VO+2 Redox Couple on Carbon Paper Electrode with Heat Treatment

Carbon paper was heat-treated at different temperatures and used as an electrode for the VO2+/VO+2 redox couple. Kinetics of the VO2+/VO+2 redox couple on the carbon paper electrode was studied using cyclic voltammetry (CV), polarization curves (PC), and electrochemical impedance spectroscopy (EIS). Results obtained from CV and PC show that the reaction rate constant and the exchange current of the VO2+/VO+2 redox couple on the carbon paper electrode increase as the heat treatment temperature increases. An equivalent circuit model for the VO2+/VO+2 redox couple on the carbon paper electrode was established. Fitting the experimentally obtained electrochemical impedance spectra with established equivalent circuits shows that heat treatment increases the double-layer capacitance of the carbon paper electrode and reduces the charge transfer resistance of the VO2+/VO+2 redox couple. Similar diffusion coefficients for VO2+ and VO+2 were obtained from CV and EIS, indicating that the established equivalent circuit model is consistent with the electrode process for the VO2+/VO+2 redox couple.