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

我们将聚苯乙烯磺酸盐组成的微球分散在水中，并用离子交换树脂彻底去离子。这种悬浮液不允许进行常规的电化学测量，因为它是高电阻的。然而，微电极技术可以获得氢离子的还原波。由于大部分氢离子被微球静电固定，因此电流很小。如果在悬浮液中加入盐，由于氢离子从微球中释放出来，电流会急剧增加。换句话说，悬架中的电流非常敏感。这种灵敏度可以应用于微电极上盐的局部检测。本项目涉及在扫描电化学显微镜下检测几种盐浓度下聚苯乙烯磺酸微球释放的氢离子电流。当该技术应用于弱酸时，微电极上的电流与浓度成正比，因为它参与了酸的解离。用交流阻抗法测定了悬浮液在氢离子还原作用下的电阻。然后它显示出比酸的摩尔电导估计的更高的电阻，可能是由于解离的贡献。合成的微球直径为0.7 μm，粒径分散很窄。在电极与绝缘壁之间的不同距离处观察到悬浮液中的稳态电流。当微电极在施加溶解电位的金属壁上扫描时，它可以检测溶解离子的还原电流。通过对当前和三维位置的分析，可以绘制出金属的图像。在此过程中，我们发现聚苯胺包覆的聚苯乙烯颗粒呈现同步电流。为了寻找同步的原因，使用扫描电化学显微镜改变电极与壁的距离。这项先进的研究仍在进行中。少

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