Characterization of the Ionic Liquid/Electrode Interfacial Relaxation Processes Under Potential Polarization for...

Area of Science:

• Electrochemistry
• Sensor Technology
• Materials Science

Background:

• Electrochemical amperometric sensors rely on redox reactions at the working electrode for analyte detection.
• Redox reactions can generate products that alter the electrode/electrolyte interface, causing problematic baseline drift in continuous sensors.
• The slow relaxation of the electrical double layer at ionic liquid/electrode interfaces complicates maintaining a stable baseline.

Purpose of the Study:

• To characterize the interfacial relaxation process in ionic liquid-based electrochemical gas (IL-EG) sensors.
• To investigate methods for minimizing baseline drift and enhancing the stability and lifetime of IL-EG sensors.

Main Methods:

• Performed multiple potential step experiments on an IL-EG sensor, varying frequencies and time periods.
• Investigated the effect of ON-OFF potential modes, adjusting sensing and idle periods.
• Evaluated the impact of a conditioning step at zero volts versus open circuit potential (OCP).

Main Results:

• Shortening the sensing period and extending the idle period facilitated interfacial relaxation, reducing baseline drift.
• A conditioning step at zero volts, compared to OCP, further minimized baseline drift.
• The high viscosity of ionic liquids aids electrochemical regeneration, contributing to improved sensor performance.

Conclusions:

• Optimizing the ON-OFF potential cycling (short sensing, long idle) is crucial for interfacial recovery and reduced drift.
• Implementing a zero-volt conditioning step significantly enhances signal stability and sensor operational lifespan.
• These findings are vital for developing robust, continuous-monitoring IL-EG sensors.