Kinetically Constrained Semicrystallization of IrO<sub>2</sub> with Balanced Activity and Stability for Acidic Oxygen Evolution Reaction.
basic_science · Level V
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- Record sourced from PubMed, PMID 41963100.
- Also identified by DOI 10.1021/acs.nanolett.6c00628.
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Abstract
The activity-stability trade-off for IrO<sub>2</sub> constrains the development of proton exchange membrane water electrolyzers (PEMWEs). Conventionally, high IrO<sub>2</sub> crystallinity ensures oxygen evolution reaction (OER) stability while compromising activity, while amorphous structure offers high OER activity while sacrificing durability. Herein, we develop a kinetically constrained amorphization strategy using high-temperature thermal shock to precisely tune IrO<sub>2</sub> crystallinity, capturing an ideal intermediate state: low-crystallinity IrO<sub>2</sub> (LC-IrO<sub>2</sub>). LC-IrO<sub>2</sub> merges the high activity of amorphous IrO<sub>2</sub> derived from the short-range order and the robust stability of crystalline IrO<sub>2</sub> with structural rigidity. Consequently, the LC-IrO<sub>2</sub> catalyst simultaneously achieves excellent catalytic activity and stability for acidic OER. A PEMWE using a LC-IrO<sub>2</sub> anode requires only 1.69 V to reach 1 A cm<sup>-2</sup> at 60 °C and maintains steady operation for 500 h with a negligible degradation rate. This study demonstrates kinetic crystallinity control as a new paradigm for electrocatalyst design.