Quantitative electrochemical measurements using in situ ec-S/TEM devices.

Area of Science:

• Electrochemistry
• Materials Science
• Microscopy

Background:

• In situ electrochemical-scanning/transmission electron microscopy (ec-S/TEM) offers insights into dynamic electrochemical processes.
• Microfluidic electrochemical cells with microfabricated electrodes are key components for ec-S/TEM.
• Accurate characterization requires validation of these microfluidic cells for quantitative electrochemistry.

Purpose of the Study:

• To validate the use of microfluidic electrochemical cells for quantitative in situ electrochemistry research.
• To assess the reliability of ec-S/TEM for electrochemical measurements.
• To determine the influence of the electron beam on electrochemical data.

Main Methods:

• Utilized microfluidic electrochemical cells with glassy carbon and platinum microband electrodes in a three-electrode configuration.
• Performed cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) with a [Fe(CN)6]3-/4- redox couple.
• Analyzed electrode geometry and microfluidic conditions to determine analyte diffusion coefficients.

Main Results:

• CV and CA measurements yielded diffusion coefficients consistent with accepted values (~10-5 cm²/s).
• Electrode geometry and microfluidic conditions were accurately fitted with experimental data.
• Electron beam influence on CV scans was found to be negligible (within a few nA variation).

Conclusions:

• Quantitative electrochemistry experiments are feasible with small-scale microfluidic electrochemical cells.
• Accurate geometrical electrode configurations, diffusion boundary layers, and microfluidic conditions are crucial for reliable results.
• ec-S/TEM is a validated technique for precise electrochemical process characterization.