Ion selective redox cycling in zero-dimensional nanopore electrode arrays at low ionic strength

Area of Science:

• Electrochemistry
• Nanotechnology
• Analytical Chemistry

Background:

• Surface charge and electrical double layer (EDL) effects are crucial for ion transport in nanopores, influencing electrochemical responses in low ionic strength solutions.
• Permselective concentration polarization at nanoelectrodes is dominated by EDL effects.

Purpose of the Study:

• To fabricate and characterize zero-dimensional nanopore electrode arrays (NEAs) that couple EDL effects with redox cycling.
• To enhance electrochemical detection sensitivity and selectivity using these NEAs.

Main Methods:

• Fabrication of highly ordered, zero-dimensional nanopore electrode arrays (NEAs).
• Investigation of the interplay between EDL effects, redox cycling, and nanopore geometry.
• Characterization of current amplification and selectivity by varying supporting electrolyte concentration and redox-active species properties.

Main Results:

• Achieved current amplification up to 55-fold due to redox cycling, further enhanced by ~500-fold upon supporting electrolyte removal.
• Demonstrated the significant influence of nanopore geometry and redox-active species charge on EDL effects.
• Confirmed cation accumulation and anion repulsion in negatively charged NEAs based on limiting current changes.
• Successfully achieved selective dopamine determination in the presence of a 3000-fold excess of ascorbic acid.

Conclusions:

• NEAs effectively couple EDL effects with redox cycling for superior electrochemical detection.
• The developed NEA system offers significant current amplification and high selectivity.
• This approach provides a promising platform for sensitive and selective electrochemical analysis of analytes.