Nanometer-sized tips, scanning electrochemical

Unwin and coworkers [11] have developed a straightforward approach for fabricating platinum microelectrodes with tip sizes as small as a few nanometers. Their innovation is to use an electrophoretic paint to insulate the electrode walls while leaving an electrochemicaUy active tip exposed. These electrodes have excellent properties for use in scanning electrochemical microscopy (SECM), discussed further in Chapter 3.3. 

Sun P, Zhang ZQ, Guo JD, Shao YH (2001) Fabrication of nanometer-sized electrodes and tips for scanning electrochemical microscopy. Anal Chem 73(21) 5346-5351.doi 10.1021/ac010474w... 

Shen, M., N. Arroyo-Curras, and A. J. Bard, Achieving nanometer scale tip-to-substrate gaps with micrometer-size ultramicroelectrodes in scanning electrochemical microscopy. Anal. Chem., Vol. 83, 2011 pp. 9082-9085. 

A) and by a conical tip and a planar substrate (B). (Reprinted from J. Electroanal. Chem., 328, Mirkin, M.V., Fan, F.-R.R, and Bard, A.J., Scanning electrochemical microscopy Part 13. Evaluation of the tip shapes of nanometer size microelectrodes, 47-62, Copyright 1992, with permission from Elsevier.)... 

FIGURE 3.12 Steady-state current-distance curve for a conical tip over conductive (A) and insulating (B) substrates corresponding to different values of the parameter k=hg/ag. (A) k=3 (curve 1), 2 (curve 2), 1 (curve 3), 0.5 (curve 4), and 0.1 (curve 5). The upper curve was computed for a disk-shaped tip from Equation 3.1. (B) From top to bottom, k=3, 2, 0.5, and 0.1. The lower curve was computed for a disk-shaped tip from Equation 3.2. (Reprinted from/. Electroanal. Chem., 328, Mirkin, M.V., Ean, E.-R.R, and Bard, A.J., Scanning electrochemical microscopy Part 13. Evaluation of the tip shapes of nanometer size microelectrodes, 47-62, Copyright 1992, with permission from Elsevier.)... 

Mirkin MV, Ren FF, Bard A J (1992) Scanning electrochemical microscopy. Part 13. Evaluation of the tip shapes of nanometer size microelectrodes. J Electroanal Chem 328 47-62... 

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