How Do Liquid-Junction Potentials and Medium Polarity at Electrode Surfaces Affect Electrochemical Analyses for...

Area of Science:

• Electrochemistry
• Physical Chemistry
• Chemical Physics

Background:

• Electrochemical analysis is crucial for charge-transfer science.
• Electrode-electrolyte interfaces present interpretation challenges.
• Understanding medium polarity and liquid-junction potentials is key.

Purpose of the Study:

• To investigate medium polarity experienced by redox species at electrode surfaces.
• To quantify liquid-junction potentials between different organic solvent electrolyte solutions.
• To develop methods for evaluating charge-transfer thermodynamics, accounting for interface effects.

Main Methods:

• Utilized electron-donor-acceptor aromatic pairs as redox analytes.
• Employed electrochemical analysis to measure reduction potentials.
• Calculated differences in reduction potentials to eliminate liquid-junction effects.

Main Results:

• Medium polarity at electrode surfaces is lower than in bulk media.
• Liquid-junction potentials were measured: ~90 mV (dichloromethane-acetonitrile) and ~30 mV (benzonitrile-acetonitrile).
• The method effectively evaluated charge-transfer thermodynamics and interfacial polarity.

Conclusions:

• The study provides a method to deconvolute interfacial effects in electrochemical analysis.
• Accurate evaluation of charge-transfer thermodynamics is achievable by accounting for liquid-junction potentials.
• This work enhances the interpretation of electrochemical data in complex media.