Fe₂ Dimers for Non-Polar Diatomic O₂ Electroreduction

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• Single-atom catalysts offer high atomic efficiency but suffer from limited diatomic molecule adsorption sites.
• Activating non-polar diatomic molecules is crucial for various catalytic applications.

Purpose of the Study:

• To investigate the catalytic performance of iron dimers (Fe2) compared to single iron atoms (Fe1) for oxygen reduction reactions.
• To explore the mechanism of diatomic oxygen (O2) activation by Fe2 dimers.

Main Methods:

• Synthesis of Fe2 dimers by precise metal loading on metal-organic frameworks.
• Electrochemical testing in alkaline electrolytes to measure oxygen reduction reaction activity.
• Utilizing hydrogen atom transfer probes to study O2 activation pathways.
• Performing theoretical calculations to elucidate reaction mechanisms.

Main Results:

• Fe2 dimers exhibited a 7-fold higher specific activity for oxygen reduction compared to Fe1 counterparts.
• Distinct O2 activation modes were observed for Fe1 and Fe2 dimers.
• Theoretical calculations confirmed Fe2 dimers promote direct O=O bond cleavage, bypassing *OOH intermediates.

Conclusions:

• Fe2 dimers provide a novel catalytic pathway for efficient O2 activation through direct bond breaking.
• This mechanism leads to significantly enhanced catalytic activity and reduced hydrogen peroxide yield.
• Precisely engineered metal dimers represent a promising strategy for advanced catalyst design.