Harnessing Direct Oxo Coupling for Durable Water Oxidation via Atomic-Level Strain Engineering.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Iridium oxides are leading catalysts for the oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE).
• The conventional adsorbate evolution mechanism (AEM) is limited by a high thermodynamic barrier associated with *OOH intermediates.
• Improving OER efficiency is crucial for advancing water electrolysis and green hydrogen production.

Purpose of the Study:

• To develop a novel strain-engineering strategy for iridium oxide catalysts.
• To modulate the oxygen evolution reaction pathway and overcome kinetic limitations.
• To enhance the activity and durability of catalysts for proton exchange membrane water electrolysis.

Main Methods:

• Incorporation of erbium (Er3+) into the IrO2 framework to create Er-IrOx catalysts.
• Utilizing atomic-level compressive strain to alter the electronic structure and reaction pathways.
• Investigating the shift from the adsorbate evolution mechanism (AEM) to the direct oxo coupling mechanism (OPM).

Main Results:

• The Er-IrOx catalyst exhibited a reduced Tafel slope of 70.55 mV dec⁻¹ and an overpotential of 209 mV at 10 mA cm⁻².
• Strain-induced reconfiguration shifted the OER pathway to the direct oxo coupling mechanism (OPM), bypassing high-energy intermediates.
• The catalyst demonstrated excellent performance in a practical PEMWE, achieving 6 A cm⁻² at 1.899 V and maintaining stability for over 400 hours.

Conclusions:

• Atomic-level compressive strain engineering using Er3+ is an effective strategy to enhance OER catalysis.
• The developed Er-IrOx catalyst offers a promising solution for efficient and durable water electrolysis.
• This approach provides a generalized method for improving iridium-based catalysts, supporting the commercialization of green hydrogen.