NANOMETER-SIZED ELECTROCHEMICAL SENSORS

Citation
Yh. Shao et al., NANOMETER-SIZED ELECTROCHEMICAL SENSORS, Analytical chemistry, 69(8), 1997, pp. 1627-1634
Citations number
38
Categorie Soggetti
Chemistry Analytical
Journal title
ISSN journal
00032700
Volume
69
Issue
8
Year of publication
1997
Pages
1627 - 1634
Database
ISI
SICI code
0003-2700(1997)69:8<1627:NES>2.0.ZU;2-Z
Abstract
Nanometer-sized glass-sealed metal ultramicroelectrodes (UMEs) have be en prepared using a laser-based micropipet puller. The tip was exposed to solution either by etching away a small portion of glass insulator or by micropolishing. The characterization of the UMEs was carried ou t by a combination of steady-state voltammetry, scanning electron micr oscopy (SEM), and scanning electrochemical microscopy (SECM). The cycl ic voltammograms obtained have a regular shape with very small capacit ive and resistive background. The effective electrode radii obtained f rom voltammetry were between 2 and 500 mn. From the SEM micrographs, t he shape of polished tips appears to be close to a microdisk, while th e geometry of etched electrodes is closer to conical. Accordingly, the SECM current-distance curves (i(T)-d) obtained with polished electrod es fit well the theory for a disk-shaped tip, while a 20-nm-radius etc hed electrode was shown to be a fairly sharp cone with a height-to-rad ius ratio of about 2.5. The experimental data were compared to the the ory developed for disk-shaped, conical, and recessed tips to demonstra te suitability of the produced electrodes for quantitative electrochem ical experiments. The prospects of steady-state measurements of the ra tes of fast heterogeneous reactions are discussed. Submicrometer-sized ion selective electrodes (ISEs) were prepared by coating etched Ag ti ps with silver iodide. The concentration response of such ISEs remaine d stable and linear after coating of the ISEs with protective Nafion f ilm.