Graphene Coating of Nafion Membranes for Enhanced Fuel Cell Performance

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Nafion membranes are crucial for fuel cells but suffer from fuel crossover.
• Direct methanol fuel cells (DMFCs) require efficient membranes to prevent methanol and hydrogen crossover.

Purpose of the Study:

• To develop a graphene-based barrier for Nafion membranes to mitigate fuel crossover.
• To enhance the performance of direct methanol fuel cells using modified membranes.

Main Methods:

• Coating Nafion membranes with aqueous dispersions of electrochemically exfoliated graphene (e-G) using a spray process.
• Characterization of the graphene layers using scanning transmission electron microscopy and electron energy-loss spectroscopy.
• Evaluating fuel cell performance, specifically power density, in a direct methanol fuel cell setup.

Main Results:

• Formation of a dense, percolated e-G flake network acting as an effective diffusion barrier.
• Achieved a 3.9-fold increase in maximum power density for e-G-coated Nafion N115 compared to bare Nafion N115 (39 vs 10 mW cm⁻² at 0.3 V) with a 5M methanol feed.
• Demonstrated selective barrier properties against methanol and hydrogen crossover.

Conclusions:

• Electrochemically exfoliated graphene-coated Nafion membranes offer a promising solution for reducing fuel crossover in DMFCs.
• The enhanced membrane performance supports the application of e-G-coated Nafion in portable DMFCs utilizing concentrated methanol fuels.