Dual-regulated cascade catalysis via spatial synergy and electronic coupling for efficient oxygen reduction reaction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Iron-nitrogen-carbon (Fe-NC) materials are promising platinum alternatives for oxygen reduction reaction (ORR).
• Single-active-site configurations in Fe-NC catalysts are limited by linear scaling relationships, causing sluggish kinetics.
• Developing efficient non-precious metal electrocatalysts is crucial for energy applications.

Purpose of the Study:

• To design and synthesize a dual-site cascade electrocatalyst for enhanced ORR performance.
• To elucidate the synergistic mechanism between ZnS nanoparticles and FeN4 sites.
• To overcome the intrinsic limitations of traditional Fe-NC catalysts.

Main Methods:

• One-step pyrolysis synthesis of ZnS nanoparticles integrated with FeN4-enriched N, S-codoped carbon matrices (ZnS-Fe-NSC).
• Comprehensive experimental characterization (e.g., electrochemical testing).
• Theoretical investigations (e.g., DFT calculations) to understand the reaction mechanism.

Main Results:

• The ZnS-Fe-NSC catalyst exhibited a half-wave potential of 0.96 V, a 120 mV improvement over single-site catalysts.
• Achieved near-theoretical four-electron selectivity and a kinetic current density of 44.52 mA cm⁻² at 0.8 V, 5.6 times that of commercial Pt/C.
• Demonstrated a peak power density of 193 mW cm⁻² and over 200 hours of stable operation in zinc-air batteries.

Conclusions:

• The dual-site cascade design with spatial-electronic regulation successfully reconstructs the ORR pathway, enhancing catalytic activity.
• ZnS sites facilitate oxygen activation and *OOH intermediate generation, while FeN4 sites optimize electron transfer.
• This work provides a universal framework for designing multi-component non-precious metal electrocatalysts through synergistic effects.