Voltammetric Scanning Electrochemical Cell Microscopy: Dynamic Imaging of Hydrazine Electro-oxidation on Platinum Electrodes
Voltammetric Scanning Electrochemical Cell Microscopy: Dynamic Imaging of Hydrazine Electro-oxidation on Platinum Electrodes
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DOI：
10.1021/acs.analchem.5b00988
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发表时间：
2015-06-02
影响因子：
7.4
通讯作者：
Unwin, Patrick R.
中科院分区：
文献类型：
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作者：
Chen, Chang-Hui;Jacobse, Leon;Unwin, Patrick R.
伏安扫描电化学电池显微术（SECCM）通过在图中的每个像素处记录宽电位窗口中的电化学电流，将循环伏安法测量结合在SECCM成像协议中。与传统的固定电位成像相比，这提供了更多的信息。数据可以表示为一系列电位下的电流（在表面区域上）的电影（数百帧），并且高度揭示了电极活动的细微变化。此外，通过将SECCM数据与其他形式的显微镜，例如，扫描电子显微镜和电子背散射衍射数据相结合，可以直接将电流电压特性与空间位置和表面结构相关联。在这项工作中，我们使用了“跳跃模式”，其中SECCM移液器探头在一系列位置向表面平移，直到弯月面接触表面上留下的少量残留物，在探头缩回时，区分每个测量的精确区域。我们使用这些技术来研究在空气中和脱气环境中的多晶铂衬底上的肼氧化。在这两种情况下，检测到的法拉第电流显示出对表面晶体取向的结构依赖性。值得注意的是，在氧气（充气溶液）的存在下，几乎所有晶粒（结晶取向）的电化学电流都强烈降低。结果突出了伏安SECCM电化学成像的灵活性和肼电分析提出了重要的影响。
Voltammetric scanning electrochemical cell microscopy (SECCM) incorporates cyclic voltammetry measurements in die SECCM imaging protocol, by recording electrochemical currents in a wide-potential window at each pixel in a map. This provides much more information compared to traditional fixed potential imaging Data can he represented as movies (hundreds of frames) of current (over a surface region) at a series of potentials and are highly revealing of subtle variations in electrode activity. Furthermore, by combining SECCM data with Other forms of microscopy, e.g, scanning electron microscopy and electron backscatter diffraction data, it is possible to directly relate the current voltage characteristics to spatial position and surface structure. In this work we use a "hopping mode", where the SECCM pipet probe is translated toward the surface at a series of positions until meniscus contact Small amounts of residue left on the surface, upon probe retraction, demark the precise area of each measurement. We use these techniques to study hydrazine oxidation on a polycrystalline platinum substrate both in air and in a deaerated environment. In both cases, the detected faradaic current shows a structural dependence on the surface crystallographic orientation. Significantly, in the presence of oxygen (aerated solution) the electrochemical current decreases strongly for almost all grains (crystallographic orientations). The results highlight the flexibility of voltammetric SECCM for electrochemical imaging and present important implications for hydrazine electroanalysis.