Disentangling conduction pathways at the ionic-electronic interface in EMI-TFSI-covered graphene transistors

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Electron and ion transport at carbon surfaces are vital for membrane processes, batteries, and supercapacitors.
• Ion transport in nanoporous electrodes is influenced by electronic conductance and interfacial capacitance.

Purpose of the Study:

• To investigate ion-electron coupling and transport in a single-crystal graphene transistor.
• To disentangle in-plane ionic and electronic transport using in-plane impedance spectroscopy.

Main Methods:

• Utilized in-plane impedance spectroscopy on a graphene transistor covered with an ionic liquid (EMI-TFSI).
• Performed gate- and temperature-dependent measurements to analyze charge carrier density and electrolyte conductivity.

Main Results:

• Successfully extracted both electronic and ionic conductance across a range of conditions.
• Demonstrated decoupling of ionic and electronic transport pathways at the microscale.
• Observed this decoupling despite high capacitive coupling at the carbon-ionic liquid interface.

Conclusions:

• The findings align with theoretical predictions regarding length scales in electronic-ionic interfacial transport.
• Provides insights into fundamental transport mechanisms relevant to electrochemical energy storage and membrane technologies.