Center for Electrochemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, USA.
Anal Chem. 2011 Dec 1;83(23):9082-5. doi: 10.1021/ac2021294. Epub 2011 Nov 9.
Scanning electrochemical microscopy (SECM) tips with rounded glass insulation around the metal wire (radius a = 5 μm) were fabricated (apparent RG < 1.1, where RG is the ratio of the radius of the insulation sheath divided by the electrode radius), and their SECM feedback approach curves were studied in solutions of tris(2,2'-bipyridine)ruthenium(2+) (Rubpy) in acetonitrile and ferrocenemethanol in water with a platinum disk as the substrate electrode (radius a(s) = 1 mm). Considerable enhancement of the normalized feedback current, I(T)(L) = i(T)/i(T,∞), where L = d/a and d is the distance traveled by the SECM tip, was observed in both systems (e.g., I(T)(L) = 15 in organic solutions and I(T)(L) = 30 in aqueous solutions) with good electrode alignment. This shows that tip-to-substrate gaps of ca. d = 110 nm can be achieved. To account for any deviations from the usual disk UME behavior and currents caused by possible changes in the tip electrode geometry, simulations of the feedback response were performed for a 2D axisymmetric environment. All simulated results match in a point-to-point comparison with experimental values (average relative standard deviation (RSD) = 0.01 ± 0.005).
制备了带有金属丝周围圆形玻璃绝缘的扫描电化学显微镜（SECM）尖端（表观 RG < 1.1，其中 RG 是绝缘护套半径与电极半径的比值），并在以铂盘为基底电极的乙腈中的三（2,2'-联吡啶）钌（2+）（Rubpy）溶液和水中的二茂铁甲醇中研究了它们的 SECM 反馈接近曲线（半径 a(s) = 1 毫米）。在两种系统中（例如，在有机溶液中 I(T)(L) = 15，在水溶液中 I(T)(L) = 30），当电极对准良好时，观察到归一化反馈电流 I(T)(L) = i(T)/i(T,∞)的显著增强，这表明可以实现约 d = 110nm 的尖端-基底间隙。为了说明可能由于尖端电极几何形状的变化而导致的与通常的盘 UME 行为和电流的任何偏差，针对二维轴对称环境对反馈响应进行了模拟。所有模拟结果都与实验值进行了点对点比较（平均相对标准偏差（RSD）= 0.01 ± 0.005）。
