Quantitative Electrochemical Measurements Using In Situ ec-S/TEM Devices. (11th March 2014)

• Record Type: Journal Article
• Authors: Unocic, Raymond R.; Sacci, Robert L.; Brown, Gilbert M.; Veith, Gabriel M.; Dudney, Nancy J.; More, Karren L.; Walden, Franklin S.; Gardiner, Daniel S.; Damiano, John; Nackashi, David P.
• Is Part Of: Microscopy and microanalysis. Volume 20:Number 2(2014:Apr.)
• Page Start: 452
• Page End: 461
• Publication Date: 2014-03-11
• Subjects: Microscopy -- Periodicals; Microchemistry -- Periodicals; 502.82
• DOI: 10.1017/S1431927614000166
• Languages: English
• ISSNs: 1431-9276

Abstract

<abstract abstract-type="normal"> <title>Abstract</title> <p>Insight into dynamic electrochemical processes can be obtained with <italic>in situ</italic> electrochemical-scanning/transmission electron microscopy (ec-S/TEM), a technique that utilizes microfluidic electrochemical cells to characterize electrochemical processes with S/TEM imaging, diffraction, or spectroscopy. The microfluidic electrochemical cell is composed of microfabricated devices with glassy carbon and platinum microband electrodes in a three-electrode cell configuration. To establish the validity of this method for quantitative <italic>in situ</italic> electrochemistry research, cyclic voltammetry (CV), choronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were performed using a standard one electron transfer redox couple [Fe(CN)<sub>6</sub>]<sup>3−/4−</sup>-based electrolyte. Established relationships of the electrode geometry and microfluidic conditions were fitted with CV and chronoamperometic measurements of analyte diffusion coefficients and were found to agree with well-accepted values that are on the order of 10<sup>−5</sup> cm<sup>2</sup>/s. Influence of the electron beam on electrochemical measurements was found to be negligible during CV scans where the current profile varied only within a few nA with the electron beam on and off, which is well within the hysteresis between multiple CV scans. The combination of experimental results provides a validation that quantitative electrochemistry experiments can be performed with these small-scale microfluidic electrochemical cells provided that accurate geometrical electrode configurations, diffusion boundary layers, and microfluidic conditions are accounted for.</p> </abstract>