Molecular analysis of adsorbed layers on electrode surfaces by in-situ gravimetric methods

该项目的目标是(1)发展电化学体系中的原位重量分析方法；(2)阐明电极表面的吸附层和电化学反应的精细结构。结果概述如下1。建立了高灵敏度电化学石英晶体微天平(EQCM)。EQCM的灵敏度为0.1赫兹(质量为2 ng/cm^2)，采样时间为0.1秒，因此可以精确测量远低于单层水平的频率变化。并构建了数据采集与分析系统，将频率变化与同步测量的电势、电流存储在一起。吸附层的精细结构及其在铂电极表面的电化学反应(1)水分子在铂电极上的吸附由所谓的氢区和双层区的频率降低清楚地显示出来。…表面吸附氧层的形成机理S根据铂表面氧化过程中吸附的水分子的量和消耗的电荷与电位的关系提出了更多的观点。(2)对烷基硫醇自组装过程的原位和动态监测表明，烷基硫醇通过两个吸附速率不同的连续吸附步骤形成了定向的单分子膜。一开始是快，后来是慢。该单分子膜的氧化还原导致氧化单分子膜与溶液中的阴离子之间的离子配对。离子对的形式和单分子膜中的溶剂量强烈地依赖于单分子膜的结构。(3)阐明了参与离子输运的离子在聚吡咯薄膜氧化还原开关过程中的一致性是聚合反应和氧化还原反应中使用的络合阴离子、络合电极电位和膜厚度的函数。以及在电极表面提供特定功能的吸附层的结构和化学反应。较少

Objectives of this project are(1)to develop in-situ gravimetric methods in an electrochemical system and(2)to clarify the fine structure of adsorbed layers and electrochemical reactions on electrode surfaces. An outline of the results is described below.1. Development of in-situ gravimetric methodsThe highly sensitive electrochemical quartz crystal microbalancc(EQCM)was constructed. Sensitivity of the EQCM is 0.1 Hz in frequency(2 ng/cm^2 in mass)for 0.1 sec sampling time so that the frequency change much below a monolayer level can be measured accurately. A data acquisition and analysis system was also constructed, to which frequency change was stored with simultaneously measured potential and current.2. Fine structure of adsorbed layers and electrochemical reactions on cieclrode surfaces(1) Adsorption of water molecules on a platinum electrode was demonstrated clearly by frequency decrease in so-called hydrogen and double-layer regions. Formation mechanism of adsorbed oxygen laycr wa … More s proposed based on potential-dependence of the amount of adsorbed water molecules and the charge consumed during the oxidation of Pt surface.(2) In-situ and dynamic monitoring of self-assembling process of alkancthiols revealed that well - oriented monolayers were constructed through two successive adsorption steps differcnt in adsorption rate. fast initially and slow subsequently. Redox of this monolayer causes ion-pairing between the oxidized monolayer and anions in solution. Formalion of THE ion-pair and the amount of solvent in the monolayer are strongly dependent on the structure of the monolayer.(3) It is clarified that the identity of ion participating in ion transport accompanying redox switching of polypyrrole films is a function of cleclrolyte anion used in the polymerization and the redox reaction, cleclrode potential, and film thickness.The present new findings give the fundamental but extremely useful informations concerning the structure of double-laser. and the structure and the cleetrochemical reaction of adsorbed layer which provides specific functions on the cleclrode surface. Less