COMBINATION OF SCANNING ELECTROCHEMICAL MICROSCOPY AND LOCAL ELECTROCHEMICAL IMPEDANCE METHOD

将扫描电化学显微镜（SECM）与局部电化学阻抗法（LEIM）、扫描液滴池（SDC）和液相离子枪等微电化学技术相结合，在几μm到几十μm的尺度上研究了金属-溶液界面电化学反应的不均匀性。此外，SECM的性能进行了改进，以获得更精确的探针电流图像。得到以下结果.将用于SECM的微盘铂电极与用于LEIM的微铂黑电极组合。将嵌入环氧树脂中的铂箔用作模型试样电极。尽管LEIM的横向分辨率是SECM的几十倍，但SECM和LEIM图像都能清晰地区分铂箔和环氧树脂。SDC，其中电解质溶液的液滴可以在试样电极表面上扫描，与SECM相结合。不 ...更多信息 用SDC测量了多晶金电极的伏安和阻抗谱，发现所有晶粒都具有（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。阳极氧化膜的局部形成可以通过SECM进行评价。采用氯化银包覆的微银电极作为SECM的探针电极。利用微电极的阴极极化作用，可在局部产生少量的氯离子，称为“液相离子枪”。利用液相离子枪成功地诱发了铁电极钝化膜的局部击穿。引发局部击穿所需的临界氯离子量取决于成膜条件、膜内电场和溶液pH值.通过检测阳极极化过程中与成膜过程平行的氧析出，测量了钛电极在硫酸溶液中的探针电流图像。该探针电流图像与用常规SECM测量获得的探针电流图像一致，其中亚铁氰化物离子的氧化还原体系用作介体。探针电流图像与光学显微镜照片的比较表明，氧析出的不均匀性取决于基体钛的晶向，氧析出优先发生在较薄的钝化膜或施主密度较高的钝化膜上。少

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