Crystal Field Engineering of Bioinspired Dual-Metal Single-Atom Catalysts Via Spin-State Modulation for Efficient...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen reduction reaction (ORR) is crucial for energy technologies but limited by slow kinetics.
• Existing catalysts face challenges with intrinsic activity and mass transport.

Purpose of the Study:

• To develop a bioinspired strategy combining crystal field engineering and hierarchical porosity for enhanced ORR.
• To investigate the synergistic effects of dual-atomic sites (Fe/Co) on N-doped carbon matrices.

Main Methods:

• Synthesis of hierarchical meso/microporous N-doped carbon matrices anchored with Fe/Co dual-atomic sites (MPNC-FeCo-x).
• Electrochemical characterization of ORR performance in alkaline media.
• Deployment in zinc-air batteries to assess power density and cycling stability.
• Mechanistic studies including spin state analysis and interfacial kinetic analysis.

Main Results:

• The optimized MPNC-FeCo-4 catalyst achieved a high half-wave potential (0.923 V) and turnover frequency (2.01 e-/site-1 s-1).
• Zinc-air batteries using this catalyst demonstrated ultrahigh peak power density (232.81 mW cm-2) and over 800 hours of stable cycling.
• Co atoms were shown to modulate the Fe spin state, enhancing intrinsic activity, while hierarchical pores improved mass transport.

Conclusions:

• The integrated approach of crystal field engineering and hierarchical porosity effectively addresses ORR limitations.
• This work provides a new paradigm for manipulating spin states in multi-metallic single-atom catalysts for energy conversion.
• The findings offer fundamental insights into structure-activity relationships for advanced ORR catalysts.