Dynamic diffuse double-layer model for the electrochemistry of nanometer-sized electrodes
Dynamic diffuse double-layer model for the electrochemistry of nanometer-sized electrodes
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DOI：
10.1021/jp060084j
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发表时间：
2006-02-23
影响因子：
3.3
通讯作者：
Wu, BL
中科院分区：
文献类型：
--
作者：
He, R;Chen, SL;Wu, BL
开发了动态扩散双层模型来描述发生氧化还原反应的电极/电解质界面。它克服了基于耗尽层和Frumkin双层效应模型的传统伏安理论在预测纳米电极伏安行为时的困境。从Nernst-Planck方程出发，推导出动态界面浓度分布，其形式与Boltzmann分布方程类似，但包含电流密度的影响。将动态浓度分布分别纳入泊松方程和巴特勒-沃尔默方程，产生包含电流影响的动态电势分布方程和包含双层效应的伏安方程。基于这两个方程的计算给出了界面结构（电位和浓度分布）和伏安行为。结果表明，纳米尺度电极的电化学界面更像是双电层，而大于100 nm的电极界面可以视为浓度耗尽层。纳米级电极/电解质界面的双层性质导致伏安响应随电极尺寸、反应物电荷、形式氧化还原电位值和致密双层的介电特性而变化。与基于耗尽层中氧化还原分子传输的传统伏安理论相比，这些伏安特性是新颖的。
A dynamic diffuse double-layer model is developed for describing the electrode/electrolyte interface bearing a redox reaction. It overcomes the dilemma of the traditional voltammetric theories based on the depletion layer and Frumkin's model for double-layer effects in predicating the voltammetric behavior of nanometer-sized electrodes. Starting from the Nernst-Planck equation, a dynamic interfacial concentration distribution is derived, which has a similar form to the Boltzmann distribution equation but contains the influence of current density. Incorporation of the dynamic concentration distribution into the Poisson and Butler-Volmer equations, respectively, produces a dynamic potential distribution equation containing the influence of current and a voltammetric equation containing the double-layer effects. Computation based on these two equations gives both the interfacial structure (potential and concentration profiles) and voltammetric behavior. The results show that the electrochemical interface at electrodes of nanometer scales is more like an electric-double-layer, whereas the interface at electrodes larger than 100 nm can be treated as a concentration depletion layer. The double-layer nature of the electrode/electrolyte interface of nanometer scale causes the voltammetric responses to vary with electrode size, reactant charge, the value of formal redox potential, and the dielectric properties of the compact double-layer. These voltammetric features are novel in comparison to the traditional voltammetric theory based on the transport of redox molecules in the depletion layer.