Study of ultramicroelectrode-based-measurement system for polymer electrolyte/electrocatalyst interface

针对目前三电极体系难以应用的聚合物电解质膜/电催化剂层状结构电化学测试系统，通过制作一系列超微电极，构建了电化学测试系统。该系统成功地使我们能够评估的基础上，即使在高电阻率介质中的小电流引起的小iR下降的界面电化学反应。此外，微阵列电极揭示了电催化过程的反应机理。在此基础上，开发了聚合物电解质燃料电池（PEFC）电化学测试系统。主要研究成果归纳如下。首先，一个集成的超微电极已被制造，其中包括工作，反和参考微电极在一个玻璃毛细管的尖端。利用该电极测量了氢气和甲醇氧化的气相电化学反应。第二，聚合物电解质膜的离子电导率已经通过改变水：甲醇的混合比，采用叉指型微阵列电极测量。这对于直接甲醇燃料电池的运行是有价值的。第三，利用叉指型微阵列电极，甲醇氧化中间体，这不能记录在传统的旋转环盘电极，已被首次检测。其次，制备了一种多孔微电极，其尖端具有微腔，用于测量颗粒材料的电化学性质。这允许对粉末形式的电催化剂进行常规评价。最后，一个多孔的胶束电极，它具有聚合物电解质/电催化剂在尖端的层状结构，已被创建的目的，以评价膜电极组件（MEA）的电化学。总之。通过设计和制备新型超微电极，聚合物电解质膜/电催化剂结构的电化学表征取得了很大进展。

Electrochemical measurement system for polymer electrolyte membrane/electrocatalyst layered structure, where the three-electrode system was difficult to apply so far, has been constructed by creating a series of ultramicroelectrodes. The system successfully enabled us to evaluate the interfacial electrochemical reaction based on a small-current-induced small iR drop even in the high resistivity medium. In addition, microarray electrode revealed a reaction mechanism of the electrocatalytic process. Consequently, electrochemical measurement system for polymer electrolyte fuel cell (PEFC) has been developed. Main research results are summarized as follows. First, an integrated ultramicroelectrode has been fabricated which involves working, counter and reference microelectrodes at a tip of a glass capillary. By using this, the gas phase electrochemical reactions were measured for hydrogen and methanol oxidation. Second, ionic conductivity of polymer electrolyte membrane has been measured employing an interdigitated microarray electrode by changing a water:methanol mixture ratio. Which is worthwhile for an operation of direct methanol fuel cell (DMFC). Third, by utilizing the interdigitated microarray electrode, methanol oxidation intermediate, which could not recorded at a conventional rotating ring-disk electrode, has been detected for the first time. Next, a porous microelectrode has been made which has a microcavity at the tip to measure electrochemical properties of particulate materials. This allowed a conventional evaluation of electrocatalysts in a powder form. Finally, a porous microring electrode, which has polymer electrolyte/electrocatalyst layered structure at the tip, has been created for a purpose to appraise a membrane electrode assembly (MEA) electrochemically. In conclusion. By designing and fabricating novel ultramicroelectrodes, electrochemical characterization for polymer electrolyte membrane/electrocatalyst structure has been greatly progressed.