Aoki Koichi Jeremiah, Chen Jingyuan, He Ridong
Electrochemistry Museum, Fukui 910-0804 Japan.
Department of Applied Physics, University of Fukui, 3-9-1 Bunkyo, Fukui 910-0017 Japan.
ACS Omega. 2020 Mar 24;5(13):7497-7502. doi: 10.1021/acsomega.0c00301. eCollection 2020 Apr 7.
Potential-step chronoamperometry was made at a platinum wire electrode in KCl aqueous solution at the aim of finding the behavior of the power law of the time or the constant phase element for the double-layer (DL) capacitances. The logarithmic current decays linearly with the time shorter than 0.1 ms, and then it obeys the power law in which it has a linear relation with the logarithmic time in the millisecond time domain. The transition from the exponential decay to the power law was expressed theoretically for the model of a series combination of the resistance and the DL capacitance. The expression predicts that the double logarithmic plots of the current-time provide a capacitance value at 1 s from the intercept, independent of the resistance. This prediction was demonstrated experimentally in KCl solutions of which concentrations ranged from 1 mM to 0.5 M. The capacitance can be evaluated simply by chronoamperometry on a 1 s time scale without considering any resistance effect. The capacitance values did not vary with the applied potential.
为了研究双层（DL）电容的时间幂律行为或常相位元件，在氯化钾水溶液中的铂丝电极上进行了电位阶跃计时电流法。在短于0.1 ms的时间内，对数电流随时间呈线性衰减，然后在毫秒时域内服从与对数时间呈线性关系的幂律。从指数衰减到幂律的转变在理论上是针对电阻与DL电容串联组合的模型进行表达的。该表达式预测，电流-时间的双对数图从截距可得到1 s时的电容值，与电阻无关。这一预测在浓度范围从1 mM到0.5 M的氯化钾溶液中得到了实验验证。通过计时电流法在1 s时间尺度上可以简单地评估电容，而无需考虑任何电阻效应。电容值不随施加电位而变化。
