Atomically Dispersed Fe₂ and Ni Sites for Efficient and Durable Oxygen Electrocatalysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Efficient electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for commercializing fuel cells and metal-air batteries.
• Current catalysts often rely on expensive noble metals like platinum and ruthenium, driving the need for cost-effective alternatives.

Purpose of the Study:

• To develop a novel ternary-atom catalyst for enhanced oxygen reduction and evolution reactions.
• To investigate the synergistic effects of paired Fe and single Ni sites on catalytic activity.
• To explore a sustainable alternative to noble metal-based catalysts for energy storage and conversion.

Main Methods:

• Synthesis of a ternary-atom catalyst comprising paired Fe (Fe₂-N₆) and single Ni (Ni-N₄) sites on hollow nitrogen-doped carbon microspheres.
• Electrochemical evaluation of the catalyst's activity for ORR and OER in alkaline media.
• Utilized density functional theory (DFT) calculations and in situ infrared (IR) spectroscopy to elucidate the catalytic mechanism.

Main Results:

• The synthesized ternary-atom catalyst demonstrated remarkable activity for both ORR and OER, outperforming control catalysts with single Fe or Ni sites.
• Fe₂-N₆ centers were identified as the primary active sites for both reactions.
• Ni-N₄ sites synergistically enhanced the electrocatalytic performance by optimizing the d-band centers of Fe sites.

Conclusions:

• The ternary-atom catalyst presents a highly efficient, cost-effective, and robust alternative to noble metal catalysts for ORR and OER.
• This catalyst shows significant potential for applications in rechargeable zinc-air batteries and other electrochemical energy systems.
• The synergistic interaction between different metal sites offers a promising strategy for designing advanced electrocatalysts.