Coordination modulation of iridium single-atom catalyst maximizing water oxidation activity.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) offer high activity and atom utilization for energy applications.
• Enhancing the intrinsic and specific activity of SACs remains a significant challenge.
• Electrochemical water splitting is vital for sustainable energy production.

Purpose of the Study:

• To develop a single-atom catalyst with high surface distribution density for enhanced water oxidation.
• To investigate the catalytic performance and durability of iridium SACs on nickel-iron sulfide nanosheet arrays.
• To elucidate the electronic structure effects of the substrate on catalyst activity.

Main Methods:

• Fabrication of iridium single-atom catalysts (Ir SACs) on nickel-iron sulfide nanosheet arrays (Ir1/NFS).
• Electrochemical testing in 1.0 M KOH solution to evaluate water oxidation activity (overpotential, turnover frequency).
• Assessment of catalyst stability at high current densities.
• First-principles calculations to analyze electronic structures and reaction pathways.

Main Results:

• The Ir1/NFS catalyst achieved a low overpotential of ~170 mV at 10 mA cm−2 and a turnover frequency of 9.85 s−1 at 300 mV overpotential.
• Demonstrated excellent stability, operating for 350 hours at 100 mA cm−2.
• First-principles calculations confirmed that the sulfide substrate modulates the electronic structure of Ir atoms, facilitating a favorable reaction pathway.

Conclusions:

• The developed Ir SAC on nickel-iron sulfide nanosheets exhibits superior activity and durability for electrochemical water splitting.
• This work presents a viable strategy for designing high-performance single-atom catalysts.
• The findings contribute to advancing catalysts for efficient hydrogen production via water splitting.