A new experimental method to distinguish two different mechanisms for a category of oscillators involving mass transfer
A new experimental method to distinguish two different mechanisms for a category of oscillators involving mass transfer
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DOI：
10.1016/s1388-2481(01)00237-5
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发表时间：
2001-09
影响因子：
5.4
通讯作者：
Zou Li;Q. Yuan;B. Ren;Xiaoming Xiao;Yue Zeng;Z. Tian
中科院分区：
文献类型：
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作者：
Zou Li;Q. Yuan;B. Ren;Xiaoming Xiao;Yue Zeng;Z. Tian
我们提出了新的实验证据，进一步证实电化学反应和扩散-对流（ERDC）传质的结合解释了在传输限制电流条件下出现的潜在振荡。一个典型的例子是Fe（CN）63−在碱性溶液中的还原，伴随着周期性的析氢。简单地用IO 3 −还原代替析氢作为第二载流子，就不会发生电势振荡。该置换仅去除了由析氢引起的对流传质，并保留了来自Frumkin排斥效应的负微分电阻（NDR）。因此，析氢的关键作用是通过扩散限制还原将Fe（CN）63−耗尽至零后恢复其表面浓度，而不是纯粹的第二载流子。因此，另一种机制，即强调由于静电排斥引起的Frumkin相互作用的NDR，被排除在外，因为它与振荡没有直接联系。此外，循环伏安图中的交叉循环是比负阻抗更适合这类电化学振荡器的标准。
We present new experimental evidence that further confirms that a combination of electrochemical reactions and diffusion–convection (ERDC) mass transfer accounts for the potential oscillations that appear under conditions of transport limited current. A typical example is given for the reduction of Fe(CN)63−in alkaline solution accompanying periodic hydrogen evolution. No potential oscillations occur by simply replacing the hydrogen evolution with IO3−reduction as the second current carrier. That replacement removes only the convection mass transfer induced by the hydrogen evolution, and retains the negative differential resistance (NDR) from the Frumkin repulsive effect. The key role of hydrogen evolution is thus to restore the Fe(CN)63−surface concentration after its depleting to zero by diffusion-limited reduction, rather than purely a second current carrier. Therefore, the other mechanism, which emphasizes the NDR from the Frumkin interaction due to electrostatic repulsion, is excluded because it does not have a direct connection with the oscillations. Moreover, a crossing cycle in cyclic voltammograms is a more convincible criterion for this category of electrochemical oscillators than the negative impedance.