Abstract This work demonstrates that anodic stripping voltammetry at a microdisc electrode allows the detection of silver in the absence of added supporting electrolyte. The voltammetry however becomes distorted under low-support conditions. A semi-analytical model is developed to investigate the effects of the lack of supporting electrolyte on the voltammetric responses. First, the alteration in the double-layer kinetics is studied. In particular, we show that the classical Frumkin correction cannot explain the distorted shape of the voltammetry and only accounts for no more than ~50% of the shift in the voltammetric peaks. Second, compared to the Frumkin correction, Ohmic drop contributes much more significantly to the shift in the peak potential and the distorted wave shape upon lowering electrolyte concentrations. The Ohmic drop determined on the basis of predicted constriction resistance as expressed by Newman gives a reasonable approximation to the solution resistances, especially at ionic strengths above 200 μM. In deionized water or ultra-low conductivity water with the ionic strength of sub-micromolar level, a discrepancy in the resistances of up to a factor of 25 was observed. This discrepancy likely arises due to the assumptions made in applying the Newman model to the experimental system. Finally, we show that a model which considers simultaneously the electrode kinetics and the ohmic drop effects give a consistent fit with experimental data, when the values of the resistances are appropriately adjusted to account for the inaccuracy in the approximation of constriction resistances.

中文翻译：

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无电解质银的阳极溶出伏安法：理论与实验

摘要 这项工作表明，微盘电极上的阳极溶出伏安法可以在不添加支持电解质的情况下检测银。然而，伏安法在低支持条件下会失真。开发了一个半解析模型来研究缺乏支持电解质对伏安响应的影响。首先，研究了双层动力学的改变。特别是，我们表明经典 Frumkin 校正无法解释伏安法的扭曲形状，并且仅占伏安法峰位移的不超过 50%。其次，与 Frumkin 校正相比，欧姆降对降低电解质浓度时峰值电位的偏移和扭曲的波形的贡献要大得多。根据 Newman 表示的预测收缩电阻确定的欧姆降给出了溶液电阻的合理近似值，尤其是在离子强度高于 200 μM 的情况下。在离子强度为亚微摩尔水平的去离子水或超低电导率水中，观察到高达 25 倍的电阻差异。这种差异可能是由于在将纽曼模型应用于实验系统时所做的假设而产生的。最后，我们表明，当适当调整电阻值以解决收缩电阻近似值的不准确时，同时考虑电极动力学和欧姆降效应的模型与实验数据一致。