Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Phys Rev E. 2019 Oct;100(4-1):042204. doi: 10.1103/PhysRevE.100.042204.
An immobile charged species provides a charged medium for transport of charge carriers that is exploited in many applications, such as permselective membranes, doped semiconductors, biological ion channels, as well as porous media and microchannels with surface charges. In this paper, we theoretically study the electrochemical impedance of electrodiffusion in a charged medium by employing the Nernst-Planck equation and the electroneutrality condition with a background charge density. The impedance response is obtained under different dc bias conditions extending above the diffusion-limiting bias. We find a transition in the impedance behavior around the diffusion-limiting bias and present an analytical approximation for a weakly charged medium under an overlimiting bias.
固定带电物种为载流子的传输提供了带电介质，这在许多应用中得到了利用，如选择渗透性膜、掺杂半导体、生物离子通道，以及带有表面电荷的多孔介质和微通道。在本文中，我们通过使用 Nernst-Planck 方程和背景电荷密度的电中性条件，从理论上研究了带电介质中电扩散的电化学阻抗。我们在超过扩散限制偏压的不同直流偏压条件下得到了阻抗响应。我们发现，在扩散限制偏压周围，阻抗行为发生了转变，并提出了在过限偏压下对弱带电介质的分析近似。
