Selective Proton/Deuteron Transport through Nafion|Graphene|Nafion Sandwich Structures at High Current Density

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Polyelectrolyte-membrane (PEM) fuel cells are crucial for hydrogen energy.
• Efficient ion transport across membranes is key to fuel cell performance.
• Graphene's unique properties offer potential for novel membrane applications.

Purpose of the Study:

• To investigate proton and deuteron transport through single-layer graphene in PEM-style hydrogen pump cells.
• To quantify ion conductance and selectivity of graphene for hydrogen isotopes.
• To explore the potential of graphene as a selective ion-conducting layer.

Main Methods:

• Fabrication of single-layer graphene sandwiched between Nafion membranes in a hydrogen pump cell.
• Utilizing Raman spectroscopy to confirm graphene quality and integrity.
• Measuring ion current densities and conductances under modest bias voltages.

Main Results:

• Achieved ion current densities near 1 A cm^-2 for proton and deuteron transmission.
• Obtained high area-normalized ion conductances: ~29 S cm^-2 for protons and ~2.1 S cm^-2 for deuterons.
• Demonstrated significant attenuation of potassium ion transfer while allowing substantial proton transport.

Conclusions:

• Single-layer graphene facilitates highly efficient proton and deuteron transport in PEM-style devices.
• Graphene exhibits remarkable selectivity, attenuating heavier ions significantly more than protons.
• The findings suggest graphene's potential as an advanced ion-selective layer in electrochemical applications.