Effects of the dipolar double layer on elemental electrode processes at micro- and macro-interfaces,Faraday Discussions

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Effects of the dipolar double layer on elemental electrode processes at micro- and macro-interfaces
Faraday Discussions ( IF 3.3 ) Pub Date : 2018-01-29 , DOI: 10.1039/c7fd00212b
Koichi Jeremiah Aoki _{1,

2,

3} , Jingyuan Chen _{2,

4,

5,

6}

Affiliation

Determination of heterogeneous rate constants of redox reactions or charge transfer resistances always involves ambiguities due to their participation in double layer (DL) capacitances and solution resistances. The rate constants determined by steady-state voltammograms at ultra-microelectrodes are inconsistent with time-dependent voltammograms, implying participation of the DL impedance. We examine controlling factors of DLs through the frequency-dependence of the capacitance on the basis of the definition of the current and the capacitance. The capacitance obeys the power law of the frequency. It is controlled by the orientation of a limited amount of solvent dipoles, independent of salts. Redox species, dipoles of which are oriented oppositely to the solvent dipoles, decrease the DL capacitance and make the value negative at high concentrations of the species. The decrease in the capacitance increases the real impedance, as predicted from the phase angle, yielding an extra resistance. This may be a ghost charge transfer resistance. However, there are actually a number of well-defined charge transfer resistances, which are observed as transferring rates through films on electrodes.

中文翻译：

偶极双层对微界面和宏观界面上元素电极过程的影响

氧化还原反应或电荷转移电阻的异质速率常数的确定总是很含糊，因为它们参与了双层（DL）电容和溶液电阻。在超微电极上由稳态伏安图确定的速率常数与时间依赖性伏安图不一致，这意味着DL阻抗的参与。我们根据电流和电容的定义，通过电容的频率依赖性来检查DL的控制因素。电容遵守频率的功率定律。它由有限量的溶剂偶极子的取向控制，而与盐无关。氧化还原物质，其偶极子与溶剂偶极子的方向相反，降低DL电容，并在高浓度物质时将其值设为负。如根据相角所预测的，电容的减小会增加实际阻抗，从而产生额外的电阻。这可能是重影电荷转移电阻。但是，实际上存在许多定义明确的电荷转移电阻，它们被视为通过电极上薄膜的转移速率。

更新日期：2018-10-10

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