Atomically Dispersed Zr-N Moieties Modulate Fe Coordination for Robust Oxygen Reduction Electrocatalysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Iron-nitrogen-carbon (Fe-N-C) materials are promising non-precious metal catalysts for the oxygen reduction reaction (ORR).
• Long-term stability of Fe-N-C catalysts is limited by Fe dissolution and carbon corrosion.
• Developing stable and efficient ORR catalysts is crucial for energy technologies like fuel cells and metal-air batteries.

Purpose of the Study:

• To develop a highly stable and efficient non-precious metal catalyst for the oxygen reduction reaction (ORR).
• To investigate the synergistic effects of dual-atom doping (Fe and Zr) on catalyst performance and stability.
• To provide design principles for next-generation ORR electrocatalysts.

Main Methods:

• One-step solid-state synthesis of a Fe-Zr dual-atom carbon-based catalyst (Fe,Zr-NC).
• Density Functional Theory (DFT) calculations to understand electronic structure and reaction mechanisms.
• Experimental characterization using Extended X-ray Absorption Fine Structure (EXAFS) and electrochemical testing (cyclic voltammetry, zinc-air battery performance).

Main Results:

• The Fe,Zr-NC catalyst exhibits a dual-metal coordination structure with atomically dispersed Zr-N units adjacent to Fe-N4 centers.
• DFT calculations and EXAFS confirmed optimal Fe-Zr synergy and weakened *OH adsorption, addressing the ORR rate-limiting step.
• The catalyst achieved a high half-wave potential (0.891 V vs RHE), negligible activity loss over 5000 cycles, outperforming Pt/C.
• In zinc-air batteries, it delivered a peak power density of 185.7 mW cm⁻² and stable operation for over 453 hours.

Conclusions:

• Dual-atom synergy in Fe,Zr-NC catalysts effectively modulates electronic structure and intermediate binding energies for enhanced ORR activity and stability.
• The developed Fe,Zr-NC catalyst presents a viable, high-performance alternative to precious metal catalysts for energy conversion applications.
• This work offers valuable insights and design strategies for creating advanced electrocatalysts for the oxygen reduction reaction.