Stabilizing High-Activity FeN₅ Sites via an Adaptive N-linked Carbon Bilayer for Stable Fuel Cells

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane fuel cells (PEMFCs) face challenges with Fe-N-C catalyst activity-stability trade-offs.
• Pyrolysis-induced defects limit the practical application of Fe-N-C catalysts.

Purpose of the Study:

• To develop a "repair-and-upgrade" strategy for Fe-N-C catalysts.
• To enhance the stability and activity of single-atom catalysts for PEMFCs.

Main Methods:

• Engineered Fe-N-C catalysts using carbon and nitrogen supplementation.
• Stabilized FeN4 moieties into FeN5 configurations via an in situ carbon bilayer.
• Integrated catalysts into membrane electrode assemblies for testing.

Main Results:

• Achieved a peak power density of 1221 mW cm⁻².
• Demonstrated exceptional durability: >85% power retention after 10,000 cycles (H₂-O₂).
• Showed negligible decay over 45 hours at 0.6 V (H₂-air).

Conclusions:

• The "repair-and-upgrade" strategy effectively stabilizes Fe-N-C catalysts.
• An adaptive local environment around Fe active sites ensures superior electrocatalytic stability.
• This approach offers a novel design for stable single-atom catalysts.