Feedback-independent Pt nanoelectrodes for shear force-based constant-distance mode scanning electrochemical microscopy.
Feedback-independent Pt nanoelectrodes for shear force-based constant-distance mode scanning electrochemical microscopy.
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DOI：
10.1021/ac061310o
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发表时间：
2006-09
影响因子：
7.4
通讯作者：
M. Etienne;E. Anderson;S. Evans;W. Schuhmann;I. Fritsch
中科院分区：
文献类型：
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作者：
M. Etienne;E. Anderson;S. Evans;W. Schuhmann;I. Fritsch
新一代的铂纳米电极的恒距模式扫描电化学显微镜（CD-SECM）已制备，其特征在于，并用于高空间分辨率的电化学测量和可视化的电化学诱导的浓度梯度在微腔。探针具有长（1- 2cm）、窄的石英尖端，其被圆锥形地抛光，并且具有稍微偏离中心的Pt纳米电极。由于探针上电极的尺寸和位置，即使在几百纳米的距离内接近被分析的样品表面时，也不会表现出SECM反馈。探针被定位在表面附近，同时通过使用非光学剪切力控制尖端到样品的距离进行扫描和电化学测量。测试结构由直径为50微米的圆柱形微腔组成，具有三个可单独寻址的电极：8微米深度的金盘，沿壁沿着4微米深度的新月形金环，以及边缘处的顶部金电极。微腔内的不同电极用于还原和氧化250微升的5 mM六胺氯化钌（III）和0.1 M氯化钾的溶液中的氧化还原物质，通过矿物油保护其不蒸发，而SECM尖端遵循结构的形貌并监测来自[Ru（NH3）6]2+氧化的电流。从这些复杂的测试结构中获得了电化学产生的浓度分布，这是目前任何其他SECM技术都不可能实现的。
A new generation of platinum nanoelectrodes for constant-distance mode scanning electrochemical microscopy (CD-SECM) has been prepared, characterized, and used for high spatial resolution electrochemical measurements and visualization of electrochemically induced concentration gradients in microcavities. The probes have long (1-2 cm), narrow quartz tips that were conically polished and have a Pt nanoelectrode that is slightly offset from center. Because of the size and location of the electrode on the probe, it does not exhibit SECM feedback while approaching the analyzed sample surfaces even to distances within a few hundred nanometers. The probe was positioned near the surface while scanning and performing electrochemical measurements through use of nonoptical shear force control of the tip-to-sample distance. Test structures consisted of cylindrically shaped microcavities that are 50 microm in diameter with three individually addressable electrodes: a gold disk at 8-microm depth, a crescent-shaped gold ring at 4-microm depth along the wall, and a top gold electrode at the rim. Different electrodes within the microcavity were used to reduce and oxidize redox species in 250 microL of a solution of 5 mM hexaamineruthenium(III) chloride and 0.1 M potassium chloride, protected from evaporation by mineral oil, while the SECM tip followed the topography of the structures and monitored the current from the oxidation of [Ru(NH3)6]2+. Electrochemically generated concentration profiles were obtained from these complex test structures that are not possible with any other SECM technology at this time.