Single-Atom Mn-N₄ Sites Engineered in Carbon Nanofiber Networks for AEMFC Oxygen Reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Oxygen reduction reaction (ORR) is kinetically limited in anion-exchange membrane fuel cells (AEMFCs).
• Platinum-group-metal (PGM)-free and iron-free catalysts are needed for ORR, especially for membrane electrode assemblies (MEAs).
• Achieving high activity and stability under operating conditions remains a challenge.

Purpose of the Study:

• To design and synthesize an effective PGM-free and iron-free catalyst for ORR electrocatalysis.
• To investigate the catalytic performance and durability of the new catalyst in AEMFCs.
• To establish design principles for advanced electrocatalysts.

Main Methods:

• Synthesis of MnN4 active sites within nitrogen-doped carbon nanofibers (MnN4@N-CNFs).
• Characterization of catalyst structure, electronic properties, and interfacial coupling.
• Electrochemical testing in alkaline media and AEMFC device operation.

Main Results:

• MnN4@N-CNFs exhibited a high half-wave potential of 0.89 V for ORR.
• The catalyst demonstrated outstanding durability and methanol tolerance.
• Achieved a peak power density of 222.0 mW cm⁻² in AEMFCs, outperforming commercial Pt/C.
• Maintained stable operation for over 15 hours.

Conclusions:

• Atomic-level engineering of MnN4@N-CNFs provides a robust framework for efficient ORR electrocatalysis.
• The developed catalyst offers a promising alternative to PGM-based catalysts for AEMFCs.
• Highlights the potential of precisely coordinated metal-N-C active sites for next-generation fuel cells.