Spatial engineering and d-orbital coupling in axial dual-atom sites for bifunctional oxygen catalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Dual-atom catalysts (DACs) show promise for electrocatalysis but precise control over metal atom coordination is difficult.
• Axial dual-atom catalysts (ADAs) offer a unique structure for tuning active sites.

Purpose of the Study:

• To develop and investigate an axial dual-atom catalyst (ADA) with precisely tuned metal coordination for enhanced bifunctional electrocatalysis.
• To explore the catalytic mechanism and performance of FeCo-ADA in oxygen reduction and evolution reactions.

Main Methods:

• Synthesis of ADA embedded in a covalent organic framework and N-doped graphene.
• Tuning of axial intermetallic distance using alcohol solvent treatment.
• In situ X-ray absorption near-edge spectroscopy (XANES) and Raman spectroscopy.
• Theoretical calculations (DFT).
• Electrochemical testing in a zinc-air battery (ZAB).

Main Results:

• FeCo-ADA exhibited efficient bifunctional electrocatalysis for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
• Fe acts as the primary active center, with Co providing synergistic effects, confirmed by in situ spectroscopy.
• Theoretical analysis revealed optimized Fe-Co orbital coupling, higher Fe oxidation state, and reduced reaction barriers.
• The FeCo-ADA based ZAB achieved high power density (464.5 mW cm⁻²) and long-term stability (3710 hours).

Conclusions:

• Rational design of axial dual-atom catalysts by tuning intermetallic distance is crucial for high-performance electrocatalysis.
• FeCo-ADA demonstrates significant potential for energy conversion applications, particularly in zinc-air batteries.
• This work provides a pathway for designing advanced catalysts with tailored electronic structures.