Kinetically Constrained Semicrystallization of IrO₂ with Balanced Activity and Stability for Acidic Oxygen Evolution...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The performance of proton exchange membrane water electrolyzers (PEMWEs) is limited by the activity-stability trade-off in iridium dioxide (IrO2) catalysts.
• High crystallinity in IrO2 enhances stability but reduces activity, while amorphous structures improve activity at the cost of durability.

Purpose of the Study:

• To develop a novel strategy for precisely controlling IrO2 crystallinity.
• To create an iridium dioxide catalyst with a balance of high activity and stability for oxygen evolution reactions (OER).

Main Methods:

• A kinetically constrained amorphization strategy using high-temperature thermal shock was employed to tune IrO2 crystallinity.
• Characterization of the resulting low-crystallinity IrO2 (LC-IrO2) to assess its structural and catalytic properties.

Main Results:

• The developed LC-IrO2 catalyst exhibits an ideal intermediate state, merging the high activity of amorphous structures with the stability of crystalline IrO2.
• PEMWEs utilizing LC-IrO2 anodes achieved high current density (1 A cm-2) at a low potential (1.69 V) at 60 °C.
• The LC-IrO2 catalyst demonstrated excellent long-term stability, operating for 500 hours with negligible degradation.

Conclusions:

• Kinetic control over crystallinity offers a new pathway for designing advanced electrocatalysts.
• LC-IrO2 presents a promising solution for enhancing the efficiency and durability of PEMWEs for the oxygen evolution reaction.