Xiong Hui, Kim Jiyeon, Kim Eunkyoung, Amemiya Shigeru
Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260.
J Electroanal Chem (Lausanne). 2009 Apr 15;629(1-2):78-86. doi: 10.1016/j.jelechem.2009.01.034.
Scanning electrochemical microscopy (SECM) is developed as a powerful approach to electrochemical characterization of individual one-dimensional (1D) nanostructures under unbiased conditions. 1D nanostructures comprise high-aspect-ratio materials with both nanoscale and macroscale dimensions such as nanowires, nanotubes, nanobelts, and nanobands. Finite element simulations demonstrate that the feedback current at a disk-shaped ultramicroelectrode tip positioned above an unbiased nanoband, as prepared on an insulating substrate, is sensitive to finite dimensions of the band, i.e., micrometer length, nanometer width, and nanometer height from the insulating surface. The electron-transfer rate of a redox mediator at the nanoband surface depends not only on the intrinsic rate but also on the open-circuit potential of the nanoband, which is determined by the dimensions of the nanoband as well as the tip inner and outer radii, and tip-substrate distance. The theoretical predictions are confirmed experimentally by employing Au nanobands as fabricated on a SiO(2) surface by electron-beam lithography, thereby yielding well defined dimensions of 100 or 500 nm in width, 47 nm in height, and 50 μm in length. A 100 nm-wide nanoband can be detected by SECM imaging with ∼2 μm-diameter tips although the tip feedback current is compromised by finite electron-transfer kinetics for Ru(NH(3))(6) (3+) at the nanoband surface.
扫描电化学显微镜（SECM）是一种强大的方法，用于在无偏置条件下对单个一维（1D）纳米结构进行电化学表征。一维纳米结构包括具有纳米级和宏观尺寸的高纵横比材料，如纳米线、纳米管、纳米带和纳米条带。有限元模拟表明，位于绝缘基板上制备的无偏置纳米带上方的盘状超微电极尖端处的反馈电流对带的有限尺寸敏感，即微米长度、纳米宽度以及距绝缘表面的纳米高度。纳米带表面氧化还原介质的电子转移速率不仅取决于固有速率，还取决于纳米带的开路电位，该电位由纳米带的尺寸以及尖端的内半径和外半径以及尖端与基板的距离决定。通过使用电子束光刻在SiO(2)表面制备的金纳米带进行实验，证实了理论预测，从而得到宽度为100或500 nm、高度为47 nm、长度为50 μm 的明确尺寸。尽管纳米带表面Ru(NH(3))(6) (3+)的有限电子转移动力学会影响尖端反馈电流，但使用直径约为2 μm的尖端通过SECM成像可以检测到宽度为100 nm的纳米带。
