Voltammetry in viscous poly(ethylene glycol) solutions at microelectrodes
Voltammetry in viscous poly(ethylene glycol) solutions at microelectrodes
复制标题
DOI：
10.1016/j.electacta.2010.11.057
复制
发表时间：
2011-04
影响因子：
6.6
通讯作者：
Yi Guo;K. Aoki;Jingyuan Chen;T. Nishiumi
中科院分区：
文献类型：
--
作者：
Yi Guo;K. Aoki;Jingyuan Chen;T. Nishiumi
二茂铁衍生物在高粘度聚乙二醇溶液（PEG）中的伏安电流与其粘度无关，与扩散控制电流结合Stokes-Einstein方程的预测相反。微电极的使用通常防止伏安图因导电性差而变形。然而，即使在直径为10μm的圆盘电极上和慢速扫描下，由于溶液的高粘度，在PEG中的扩散系数小于在水中的扩散系数，因此伏安曲线也表现出滞后现象。在微电极上通过扩散方程从峰值电流计算的扩散系数在0.1 - 160 Pas范围内为10 - 7 cm 2 s-1的数量级。它们最多比由斯托克斯-爱因斯坦方程从粘度计算的值大1000倍。这一结果的实际意义是建议使用高粘度的PEG作为固体状溶剂的可能性，而没有大的限制的质量传输。一种可能的扩散模型是氧化还原物质通过低粘性局部区域扩散，避免与聚合物网络的主链碰撞。
Voltammetric currents of the ferrocenyl derivative in highly viscous poly(ethylene glycol) solution (PEG) at microelectrodes were independent of their viscosity, contrary to the prediction from the diffusion-controlled current combined with the Stokes–Einstein equation. The usage of microelectrodes generally prevents deformation of voltammograms by poor conductivity. However, the voltammograms even at the disk electrode 10μm in diameter and slow scan rates exhibited hysteresis, because the diffusion coefficient in PEG was smaller than in water owing to high viscosity of the solution. The diffusion coefficients evaluated from the peak current through the diffusion equation at microelectrode were of the order of 10−7cm2s−1for the viscosity ranging from 0.1 to 160Pas. They are at most by 1000 times larger than the values calculated from the viscosities by the Stokes–Einstein equation. A practical significance of this result is to suggest a possibility of using highly viscous PEG as solid-like solvents without large restriction of mass transport. A possible diffusion model is that the redox species diffuses through lowly viscous local domains, avoiding collision with the backbone of the polymer network.