Enhanced spectroelectrochemistry with lossy-mode resonance optical fiber sensor

Area of Science:

• Analytical Chemistry
• Materials Science
• Optical Physics

Background:

• Spectroelectrochemical (SEC) measurements combine electrochemical (EC) and optical analyses for studying chemical reactions.
• Current SEC methods primarily focus on optical analysis of reaction products, with limited direct electrode surface monitoring.
• Enhancing SEC requires integrating real-time optical feedback from the electrode itself.

Purpose of the Study:

• To develop and validate a novel SEC approach incorporating simultaneous optical monitoring of the electrode surface.
• To utilize a polymer-clad silica fiber optic sensor coated with indium tin oxide (ITO) for dual functionality.
• To investigate the lossy-mode resonance (LMR) phenomenon in ITO for enhanced surface sensing capabilities.

Main Methods:

• Fabrication of a polymer-clad silica multimode fiber optic sensor with an ITO coating.
• Implementation of a setup enabling simultaneous EC readouts and optical spectrum analysis (including LMR).
• Conducting cyclic voltammetry (CV) and chronoamperometry (CA) experiments with redox probes (potassium ferricyanide, methylene blue).

Main Results:

• The developed sensor successfully provided three distinct interrogation readouts: EC, standard SEC optical spectra, and LMR spectra.
• LMR analysis effectively reflected the state of the sensor/electrode surface.
• Cross-correlation analysis of simultaneous EC and optical data during CA experiments provided comprehensive process understanding.

Conclusions:

• The proposed enhanced SEC method offers a significant advancement over traditional techniques.
• Simultaneous optical monitoring of the electrode surface provides complementary information to standard SEC.
• This integrated approach enhances the understanding of electrochemical processes and analyte characteristics.