Dynamic Fe─F Coordination Triggered Structure-Adaptive Fe-N-C for Efficient Oxygen Reduction Electrocatalysis.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for the oxygen reduction reaction (ORR) is crucial for widespread fuel cell adoption.
• Iron and nitrogen co-doped carbon materials (Fe-N-C) show promise as alternatives to platinum, but are limited by intrinsic scaling relationships.

Purpose of the Study:

• To design a coordination-adaptive catalyst that bypasses the linear scaling relationships limiting ORR performance.
• To investigate the role of a quasi-covalent Fe─F bond in enhancing ORR kinetics and catalyst stability.

Main Methods:

• Incorporation of a quasi-covalent Fe─F bond into Fe-N-C structure.
• Operando experimental techniques and theoretical calculations to study reaction mechanisms.
• Electrochemical testing of the F-Fe-N-C catalyst in half-cell and anion-exchange membrane fuel cell configurations.

Main Results:

• The Fe-F bond cleavage and self-healing mechanism effectively breaks the scaling relations between ORR intermediates.
• The F-Fe-N-C catalyst achieved a high half-wave potential (E1/2) of 0.91 V with exceptional stability (2 mV loss after 80,000 cycles).
• Demonstrated high performance in an anion-exchange membrane fuel cell, with a peak power density of 813 mW cm-2 (H2-air) and high current density (141 mA cm-2 at 0.9 ViR-free) in H2-O2.

Conclusions:

• The developed F-Fe-N-C catalyst offers a promising solution for efficient and durable ORR catalysis.
• This work presents a novel strategy to overcome fundamental limitations imposed by linear scaling relationships in electrocatalysis.
• The coordination-adaptive design opens new avenues for advanced catalyst development for clean energy technologies.