Current–Voltage Characteristics and Impedance Spectroscopy: Surface Conduction and Adsorption–Desorption Effects in Electrolytic Cells,The Journal of Physical Chemistry C

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Current–Voltage Characteristics and Impedance Spectroscopy: Surface Conduction and Adsorption–Desorption Effects in Electrolytic Cells
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-01-22 , DOI: 10.1021/acs.jpcc.9b11327
A. L. Alexe-Ionescu _{1,

2} , G. Barbero _{1,

3} , L. R. Evangelista ₁ , E. K. Lenzi ₄

Affiliation

We present a theoretical analysis of the current–voltage characteristics of electrolytic cells using their electrical impedance response to a simple periodic external voltage of small amplitude. The examined cell is a thin-film electrolyte (solid, liquid, or gel) sandwiched between flat electrodes at which Ohmic conduction or adsorption–desorption phenomena occur. The basic equations of the Poisson–Nernst–Planck (PNP) model are analytically solved for the case of two diffusing mobile ions (ambipolar diffusion), yielding the charge densities in thermal equilibrium and the profile of the electric potential across the sample. Proper boundary conditions permit us to explore the influence of blocking, Ohmic and adsorbing-desorbing electrodes on the final I(V) curves. Remarkable, it is possible to establish an equivalence between the Ohmic and adsorption–desorption boundary conditions for a general set of physically relevant values of the parameters characterizing the electrodes. This equivalence is a natural way to further incorporate a frequency dispersion caused by the surfaces on the whole response of the cell. This makes the approach well-tailored to investigate the role of the different diffusion coefficients for cations and anions as well as the surface effects on the voltammetry measurements in insulators containing ionic impurities.

中文翻译：

电流-电压特性和阻抗谱：电解池中的表面传导和吸附-解吸效应

我们对电解池的电流-电压特性进行了理论分析，利用它们对小幅度的简单周期性外部电压的电阻抗响应。被检查的电池是夹在扁平电极之间的薄膜电解质（固体，液体或凝胶），发生欧姆传导或吸附-解吸现象。对于两个扩散的移动离子（双极扩散），可以解析求解泊松－能斯特－普朗克（PNP）模型的基本方程式，从而得出热平衡中的电荷密度和整个样品的电势分布。适当的边界条件使我们能够探索阻塞电极，欧姆电极和吸附解吸电极对最终I（V）曲线。值得注意的是，对于表征电极的参数的一组一般物理相关值，可以在欧姆和吸附-解吸边界条件之间建立等价关系。这种等效是在单元的整个响应中进一步合并由表面引起的频率色散的自然方法。这使得该方法非常适合研究阳离子和阴离子的不同扩散系数的作用以及表面对含离子杂质绝缘子中伏安法测量的影响。

更新日期：2020-01-23

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