Bulk electronic transport impacts on electron transfer at conducting polymer electrode-electrolyte interfaces

Area of Science:

• Electrochemistry
• Materials Science
• Polymer Science

Background:

• Heterogeneous electron transfer is crucial for electrochemical devices.
• Previous research on metal, semiconductor, and carbon electrodes shows little correlation between internal electronic transport and interfacial electron transfer.
• Conducting polymers represent a novel class of electrode materials with unique charge transport properties.

Purpose of the Study:

• To investigate the relationship between electronic transport within conducting polymer electrodes and heterogeneous electron transfer kinetics.
• To explore the potential of conducting polymers in energy conversion devices.
• To optimize an electrochemical thermogalvanic cell using conducting polymer electrodes.

Main Methods:

• Utilized poly(3,4-ethylenedioxythiophene) (PEDOT) as a benchmark conducting polymer electrode.
• Employed the Ferro/ferricyanide redox couple in an aqueous electrolyte for studying electron transfer.
• Investigated the impact of polymer morphology and conductivity on electrochemical performance.
• Optimized an electrochemical thermogalvanic cell to measure power output.

Main Results:

• A strong correlation was discovered between the electronic transport within the PEDOT electrode and the rate of electron transfer to redox species.
• Percolation-based charge transport within the polymer was identified as the mechanism responsible for this correlation.
• Optimizing the PEDOT electrode's morphology and conductivity led to a four-order-of-magnitude increase in power generation from the thermogalvanic cell.

Conclusions:

• The findings establish a general phenomenon for conducting polymers, where their intrinsic percolation transport directly influences interfacial electron transfer rates.
• This understanding allows for the rational design of conducting polymer electrodes for enhanced performance in electrochemical applications.
• The optimization of electrochemical thermogalvanic cells demonstrates the practical implications of utilizing conducting polymers for efficient energy conversion.