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Local concentrations of salts by means of a scanning electrochemical microscope with microspheres

通过微球扫描电化学显微镜观察盐的局部浓度

基本信息

批准号：
11640606
负责人：
AOKI Koichi
金额：
$ 2.3万
依托单位：
Fukui University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We disperse microspheres composed of polystyrene sulfonate in water and deionize it exhaustively by means of ion exchange resins. This suspension is not allowed to make conventional electrochemical measurements because it is highly resistive. However, a microelectrode technique can permit to obtain reduction waves of hydrogen ions. Since most of hydrogen ion is immobilized electrostatically by the microsphere, the current is very small. If salt is added to the suspension, the current increases dramatically because of a release of hydrogen ion from the microsphere. In other words, the current in the suspension is quite sensitive. This sensitivity can be applied to local detection of salts at a microelectrode.This project deals with the detection of current of hydrogen ions released from polystyrene sulfonic microspheres at several concentrations of salts at the scanning electrochemical microscope. When this technique was applied to a weak acid, the current at a microelectrode was not pr … More oportional to the concentrations because of the participation in dissociation of the acid. The resistance of the suspension under the reduction of hydrogen ion was obtained by ac impedance. Then it showed higher resistance than that estimated from the molar conductance of acid, probably because of contribution of the dissociation. Microspheres were synthesized, of which diameter was 0.7 μm with a very narrow dispersion in size. Steady-state current was observed in the suspension at various distance between the electrode and an insulating wall. When the microelectrode was scanned over the a metal mounted on the wall to which a dissolution potential was applied, it could detect the reduction current of the dissolved ions. It was possible to make an image of the metal from the analysis of the current vs. three-dimensional positions. During this course, we found that the polyaniline-coated polystyrene particles showed synchronized currents. In order to pursue reasons of the synchronization, the scanning electrochemical microscope was used for changing the distance between the electrode and the wall. This advanced research is still going on. Less

将聚苯磺酸盐微球分散在水中，并用离子交换树脂对其进行彻底去离子。这种悬浮液不允许进行常规的电化学测量，因为它具有很高的电阻。然而，微电极技术可以获得氢离子的还原波。由于大多数氢离子是通过微球静电固定的，所以电流很小。如果在悬浮液中加入盐，由于氢离子从微球中释放，电流会急剧增加。换句话说，悬浮中的电流是相当敏感的。这一灵敏度可以应用于微电极上的局部盐检测。本项目研究了在扫描电化学显微镜下检测聚苯乙烯磺酸微球在几种盐浓度下释放出的氢离子的电流。当这项技术应用于弱酸时，微电极上的电流不是Pr…由于参与了酸的解离，所以对浓度的影响更大。用交流阻抗法测量了悬浮液在氢离子还原下的电阻。然后，它表现出比由酸的摩尔电导估计的更高的电阻，可能是由于解离的贡献。合成了粒径为0.7μm的微球，其分散性很小。在电极和绝缘壁之间的不同距离处，悬浮液中观察到了稳态电流。当微电极在安装在施加溶解电位的墙上的金属上扫描时，它可以检测到溶解离子的还原电流。通过对电流和三维位置的分析，可以制作出金属的图像。在这个过程中，我们发现聚苯胺包覆的聚苯乙烯粒子表现出同步电流。为了探寻同步的原因，利用扫描电化学显微镜改变电极与壁面的距离。这项高级研究仍在进行中。较少