对流扩散传质滞后的电极过程中之非Poisson涨落与非Nernst浓度极化

Non-Poisson Fluctuation and Non-Nernst Concentration Polarization in Irreversible Electrode Processes with Hysteretic Diffusion-convection Transport

根据对流扩散传质滞后的恒稳电极过程中边界层的物理图像,提出了该类电极过程的简化随机模型,建立了相应的浓度极化的随机热力学理论,揭示了非Nernst浓度极化来自于随电流密度增大电极化学反应体系涨落分布的非Poisson化与对中心极限律的偏离,进一步阐明了与滞后的扩散步骤共存的对流传质对非Nernst浓度极化的效应及其规律.同时,给出了对流引起的非Nernst浓度极化的随机热力学算例.

In accordance with the physical picture of boundary layer in the stationary electrode processes with hysteretic diffusion-convection transport we suggest a simple stochastic model to describe this kind of electrode reaction system including the effect of non-equilibrium fluctuations. As a result, a stochastic thermodynamics is established for the concentration polarization arising from hysteresis of the diffusion-convection. Based on it, we further show that the non-Nernst concentration polarization originates in the non-equilibrium fluctuation which departs from the Poisson distributions and even from the central limit theorem, but decreases by the convection companying with diffusion. An example is also given to illustrate the stochastic calculation of the non- Nernst concentration polarization affected by convection.