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COMBINATION OF SCANNING ELECTROCHEMICAL MICROSCOPY AND LOCAL ELECTROCHEMICAL IMPEDANCE METHOD

扫描电化学显微镜与局部电化学阻抗法的结合

基本信息

批准号：
10555236
负责人：
SEO Masahiro
金额：
$ 8.06万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The combinational use of scanning electrochemical microscopy (SECM) and other micro-electrochemical techniques, such as local electrochemical impedance method (LEIM), scanning droplet cell (SDC) and liquid-phase ion gun, was attempted to evaluate the heterogeneity of electrochemical reaction at the metal and solution interface in a scale of several μm to several ten μm. Furthermore, the performance of SECM was improved to obtain the more precise probe current images. The following results were obtained.1. Micro-disk platinum electrode for SECM was combined with micro-platinum black electrodes for LEIM. A platinum foil embedded into epoxy resin was used as a model specimen electrode. Both SECM and LEIM images could distinguish clearly between the platinum foil and epoxy resin although the lateral resolution of LEIM was several ten times as much as that of SECM.2. SDC, in which a droplet of electrolyte solution can be scanned over the specimen electrode surface, was combined with SECM. T … More he voltammetry and impedance spectra of a polycrystalline gold electrode measured with SDC have revealed that all grains have a (111) orientation but different azimuth angles. SDC was also applied to form locally anodic oxide films on titanium electrode surface. The local formation of anodic oxide film could be evaluated by SECM.3. A micro silver electrode covered with silver chloride was employed as a probe electrode of SECM. A small mount of chloride ions could be generated locally with a cathodic polarization of the microelectrode, which was named "liquid-phase ion gun". The use of liquid-phase ion gun succeeded in inducing the local breakdown of passive film on iron electrode. The critical amount of chloride ions needed for initiating the local breakdown depended on the film formation conditions, the electric field in film, and pH of solution.4. The probe current image of titanium electrode in sulfuric acid solution was measured by detecting oxygen which evolved from the electrode in parallel with film formation during anodic polarization. This probe current image coincided with the probe current image obtained with the conventional SECM measurement in which the redox system of ferrocyanide ions was employed as a mediator. Comparison between the probe current images and optical micrograph has indicated that the heterogeneity of oxygen evolution depends on the crystallographic orientation of the substrate titanium and the oxygen evolution takes place preferentially on the thinner passive film or the film with the higher donor density. Less

尝试将扫描电化学显微镜与其他微观电化学技术，如局部电化学阻抗法、扫描液滴池和液态离子枪相结合，在几μm到几十μm的范围内评价金属和溶液界面的电化学反应的不均一性，并进一步改进扫描电化学显微镜的性能，以获得更精确的探测电流图像。取得了以下研究成果：1.SECM的微盘铂电极与LEIM的微铂黑电极相结合。用嵌于环氧树脂中的铂箔作为模型样品电极。虽然LEIM的横向分辨率是SECM的几十倍，但LEIM和LEIM图像都能清晰地区分铂箔和环氧树脂。将SDC与SECM相结合，可以将一滴电解液扫描到样品电极表面。T…此外，用SDC测量多晶金电极的伏安和阻抗谱表明，所有的颗粒都具有(111)取向，但方位角不同。SDC还用于在钛电极表面形成局部阳极氧化膜。用SECM.3可以评价阳极氧化膜的局部形成情况。采用镀有氯化银的微银电极作为SECM的探针电极。利用微电极的阴极极化可以局部产生少量的氯离子，称为“液相离子枪”。利用液态离子枪成功地诱导了铁电极上钝化膜的局部击穿。引发局部击穿所需的氯离子临界量取决于成膜条件、膜内电场和溶液的pH值。通过检测钛电极在阳极极化过程中与成膜平行的氧，测量了钛电极在硫酸溶液中的探针电流图。该探针电流图像与传统的以亚铁氰根离子氧化还原体系为介体的SECM测量得到的探针电流图像相吻合。探针电流图像和光学显微图像的比较表明，析氧的不均匀取决于衬底钛的晶体取向，析氧优先发生在较薄的钝化膜或施主密度较高的膜上。较少