Engineering O-O formation on dual-atom Fe-Mo catalysts for oxygen electrocatalysis

Area of Science:

• Electrocatalysis
• Materials Science
• Energy Storage

Background:

• Single-atom Fe-N-C catalysts show high oxygen reduction reaction (ORR) activity but suffer from instability.
• Fenton-like reactions degrade Fe-N active sites, limiting catalyst application.

Purpose of the Study:

• To develop a stable and highly active dual-atom electrocatalyst for oxygen electrocatalysis.
• To investigate the mechanism of the dual-atom catalyst in zinc-air batteries.

Main Methods:

• Synthesis of a dual-atom oxygen electrocatalyst (FeMo/NC) with FeMoN7 active sites.
• Performance evaluation in a zinc-air battery (ZAB).
• In situ X-ray absorption spectroscopy (XAS), Raman spectroscopy, and density functional theory (DFT) calculations.

Main Results:

• The FeMo/NC catalyst demonstrated excellent bifunctional oxygen electrocatalysis.
• The FeMo/NC-based ZAB operated continuously for over 200 hours with high stability.
• In situ characterizations revealed a Fe-O-O-Mo intermediate with an oxygen bridge bond.

Conclusions:

• The Fe-O-O-Mo intermediate and synergistic Fe-Mo dual-atom sites accelerate oxygen electrocatalysis by facilitating O2 adsorption/desorption.
• DFT calculations confirmed lower energy barriers for bridged oxygen adsorption on dual-atom sites.
• The dual-atom catalyst design offers a promising strategy to overcome the limitations of single-atom catalysts.