Understanding the Bifunctional Trends of Fe-Based Binary Single-Atom Catalysts

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Single-atom catalysts (SACs) show promise for oxygen reduction (ORR) and evolution (OER).
• Binary single-atom catalysts (BSACs) offer enhanced activity over SACs.
• Understanding synergistic effects in Fe-based BSACs is crucial for bifunctional electrocatalysis.

Purpose of the Study:

• To investigate the synergistic effects of transition metals with Fe in BSACs for ORR and OER.
• To establish a theoretical understanding of FeM BSACs' bifunctional activity using DFT.
• To synthesize and experimentally validate FeM BSACs for practical applications.

Main Methods:

• Density functional theory (DFT) calculations to model catalytic activity and establish volcano relationships based on adsorption free energies.
• Facile movable type printing method for synthesizing ten types of atomically dispersed FeM anchored on nitrogen-carbon supports (FeM-NC).
• Electrochemical characterization of synthesized FeM-NC catalysts for ORR and OER performance.

Main Results:

• DFT calculations revealed a volcano relationship for FeM BSACs, predicting bifunctional activity based on transition metal identity.
• Experimental synthesis of ten FeM-NC catalysts confirmed the predicted activity trends, showing diversity between early and late transition metals.
• The optimal FeCu-NC catalyst demonstrated high ORR and OER activity, aligning with DFT predictions.

Conclusions:

• FeM BSACs exhibit tunable bifunctional activity influenced by the synergistic effects between Fe and other transition metals.
• The FeCu-NC catalyst is a highly effective electrocatalyst for rechargeable zinc-air batteries, achieving high power density (231 mW cm⁻²) and long-term stability (>300 h).
• This study provides a theoretical framework and experimental validation for designing advanced BSACs for energy storage applications.