Ultrahigh Density Ir Single-Atom Catalysts With Synergistic Ir-Ir Pairs for Efficient Acidic Oxygen Evolution

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• Single-atom catalysts (SACs) offer high efficiency but their performance is sensitive to structure.
• Synergistic effects in SACs often arise from single-atom-support interactions, with limited synergy between neighboring single atoms.
• Enhancing acidic oxygen evolution reaction (OER) performance requires novel catalyst designs.

Purpose of the Study:

• To investigate the impact of ultrahigh density single-atom Ir on Co3O4 for acidic OER.
• To explore the synergistic effects between neighboring single atoms in SACs.
• To optimize catalyst structure for improved OER activity and stability.

Main Methods:

• Synthesis of ultrahigh density Iridium (Ir) single atoms on Cobalt oxide (Co3O4) support.
• Electrochemical measurements including overpotential and stability testing.
• In situ spectroscopic characterization and density functional theory (DFT) calculations.

Main Results:

• The ultrahigh density Ir SACs achieved a low overpotential of 250 mV at 10 mA cm-2 for acidic OER.
• Catalyst stability exceeded 3000 hours at 50 mA cm-2.
• Performance in a proton exchange membrane water electrolyzer demonstrated 1.69 V at 1.0 A cm-2 with 700 hours of stable operation.
• DFT calculations revealed optimized intermediate adsorption by Ir-Ir pairs in high-density SACs.

Conclusions:

• Ultrahigh density Ir single atoms on Co3O4 effectively create neighboring Ir-Ir pairs, enhancing acidic OER.
• The optimized adsorption strength of Ir-Ir pairs is crucial for improved synergistic efficiency.
• This strategy offers a promising pathway for developing advanced electrocatalysts for water splitting.