Redox Cycling on Recessed Ring-Disk Nanoelectrode Arrays in the Absence of Supporting Electrolyte
Redox Cycling on Recessed Ring-Disk Nanoelectrode Arrays in the Absence of Supporting Electrolyte
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DOI：
10.1021/ja502052s
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发表时间：
2014-05-21
影响因子：
15
通讯作者：
Bohn, Paul W.
中科院分区：
文献类型：
--
作者：
Ma, Chaoxiong;Contento, Nicholas M.;Bohn, Paul W.
在典型的电化学实验中，使用高浓度的本底电解液，在宏观电极之间携带绝大多数电流，从而将所研究的氧化还原活性物种的电迁移传输的贡献降至最低。相反，通过利用氧化还原循环效应以及离子富集化和非屏蔽离子迁移对质量传输的贡献，在凹陷的环盘纳米电极阵列(RRDE)的循环伏安过程中，在没有支持电解液的情况下，实现了大的电流增强。极限电流随氧化还原物种Ru(NH3)(6)(2+/3+)浓度的变化有三种不同的输运模式，这表明离子输运对离子强度有很强的依赖性。在低分析物浓度下的行为特别有趣。在没有支持电解质的情况下，离子在纳米孔中积累，导致电流放大比在支持电解质存在的情况下的氧化还原循环显著增加。由于离子浓缩和离子迁移效应产生的电流增强高达100倍，加上氧化还原循环产生的类似于20倍的增强，与相同总面积的单个微电极相比，产生的总电流放大高达2000倍，使这些RRDE阵列对电化学处理和分析感兴趣。
In canonical electrochemical experiments, a high-concentration background electrolyte is used, carrying the vast majority of current between macroscopic electrodes, thus minimizing the contribution of electromigration transport of the redox-active species being studied. In contrast, here large current enhancements are achieved in the absence of supporting electrolyte during cyclic voltammetry at a recessed ring-disk nanoelectrode array (RRDE) by taking advantage of the redox cycling effect in combination with ion enrichment and an unshielded ion migration contribution to mass transport. Three distinct transport regimes are observed for the limiting current as a function of the concentration of redox species, Ru(NH3)(6)(2+/3+), revealed through the strong dependence of ion transport on ionic strength. Behavior at low analyte concentrations is especially interesting. In the absence of supporting electrolyte, ions accumulate in the nanopores, resulting in significantly increased current amplification compared to redox cycling in the presence of supporting electrolyte. Current enhancements as large as 100-fold arising from ion enrichment and ion migration effects add to the similar to 20-fold enhancement due to redox cycling, producing a total current amplification as large as 2000-fold compared to a single microelectrode of the same total area, making these RRDE arrays interesting for electrochemical processing and analysis.