Direct Oxygen-Oxygen Cleavage through Optimizing Interatomic Distances in Dual Single-atom Electrocatalysts for...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) are crucial for sustainable energy conversion, particularly in the oxygen reduction reaction (ORR).
• Challenges in SACs include controlled fabrication of single-atom sites and overcoming sluggish ORR kinetics, especially in acidic media.
• The oxygen reduction reaction (ORR) mechanism, particularly O-O bond cleavage, is a key bottleneck.

Purpose of the Study:

• To accelerate the kinetics of the oxygen reduction reaction (ORR) in acidic electrolytes.
• To develop a strategy for atomically controllable synthesis of single-atom catalysts with enhanced activity.
• To investigate the role of hetero-metal atom distance in ORR performance.

Main Methods:

• A bi-functional ligand-assisted strategy was employed to precisely control the distance between hetero-metal atoms.
• Synthesis of iron-zinc (Fe-Zn) diatomic pairs on carbon substrates.
• Electrochemical characterization and density functional theory (DFT) calculations were used to evaluate ORR performance and understand the mechanism.

Main Results:

• The synthesized Fe-Zn diatomic pairs demonstrated outstanding ORR performance in an acidic electrolyte, achieving an ultrahigh half-wave potential of 0.86 V vs. RHE.
• Experimental and theoretical studies confirmed that a specific Fe-Zn diatomic pair distance (around 3 Å) is critical for the enhanced activity.
• This precise atomic arrangement optimizes the interaction between active sites and oxygen molecules, facilitating direct O-O cleavage.

Conclusions:

• The bi-functional ligand-assisted strategy enables atomically controllable synthesis of highly active single-atom catalysts.
• Fe-Zn diatomic pairs with optimized interatomic distances significantly accelerate the oxygen reduction reaction kinetics via a direct O-O cleavage pathway.
• This work provides new insights into designing advanced SACs for energy conversion devices and addresses limitations in the ORR dissociative mechanism.