title: Quantitative electrochemical measurements using in situ ec-S/TEM devices.
abstract: Insight into dynamic electrochemical processes can be obtained with in situ 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 in situ electrochemistry research, cyclic voltammetry (CV), choronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were performed using a standard one electron transfer redox couple [Fe(CN)6]3-/4--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 10-5 cm2/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.
authors.affiliation: 1 Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, TN 37831, USA.
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Unocic
authors.affiliation: 2 Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37831, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sacci
authors.affiliation: 3 Oak Ridge National Laboratory, Chemical Sciences Division, Oak Ridge, TN 37831, USA.
authors.forename: Gilbert M
authors.initials: GM
authors.lastname: Brown
authors.affiliation: 2 Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37831, USA.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Veith
authors.affiliation: 2 Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37831, USA.
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Dudney
authors.affiliation: 1 Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, TN 37831, USA.
authors.forename: Karren L
authors.initials: KL
authors.lastname: More
authors.affiliation: 4 Protochips Inc., Raleigh, NC 27606, USA.
authors.forename: Franklin S
authors.initials: FS
authors.lastname: Walden
authors.affiliation: 4 Protochips Inc., Raleigh, NC 27606, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Gardiner
authors.affiliation: 4 Protochips Inc., Raleigh, NC 27606, USA.
authors.forename: John
authors.initials: J
authors.lastname: Damiano
authors.affiliation: 4 Protochips Inc., Raleigh, NC 27606, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Nackashi