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Confinement-Engineered Ir-IrO2 Interfaces Activate Hydrogen-Bond-Mediated Oxide Pathway Mechanism for Durable Acidic
Tongchan Lu1,2, Hao Zhao1,2, Wenjie Yu1
1Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, P. R. China.
Advanced Materials (Deerfield Beach, Fla.)
|June 24, 2026
Summary
Researchers developed a new catalyst for proton exchange membrane water electrolysis (PEMWE) using confinement engineering. This breakthrough enables durable acidic oxygen evolution reaction (OER) at low iridium loadings, overcoming previous limitations.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Durable acidic oxygen evolution reaction (OER) at low iridium loadings is critical for proton exchange membrane water electrolysis (PEMWE).
- Conventional iridium (Ir) catalysts face limitations due to adsorbate evolution mechanism scaling and degradation. The oxide pathway mechanism (OPM) is often inaccessible due to unstable Ir-Ir dual sites.
- Instability of sub-2.9 Å Ir─Ir dual sites under high anodic potentials hinders the oxide pathway mechanism (OPM).
Purpose of the Study:
- To develop a confinement-engineered strategy to stabilize Ir─Ir dual sites for activating the oxide pathway mechanism (OPM) in acidic OER.
- To investigate the mechanism of OER at engineered Ir─IrO2 interfaces under low iridium loadings.
- To achieve high activity and durability in PEMWE using a novel catalyst design.
Main Methods:
- Confinement engineering by localizing Ir precursors within a layered covalent organic framework's nanochannels and interlayer galleries.
- Synthesis of ultrathin twinned Ir─IrO2 interfaces with contracted Ir─Ir dual-site geometry (2.68 Å).
- Operando spectroscopic analyses and kinetic analysis to elucidate the OER mechanism.
Main Results:
- Successfully engineered ultrathin twinned Ir─IrO2 interfaces with a contracted 2.68 Å Ir─Ir dual-site geometry.
- Operando spectroscopy confirmed the activation of the oxide pathway mechanism (OPM) at the engineered interfaces.
- Identified a hydrogen-bond-mediated OPM (HB-OPM) that lowers the O─O coupling barrier and suppresses Ir over-oxidation.
- Achieved high activity (2 A cm⁻² at 1.71 V) and exceptional durability (>5500 h at 1 A cm⁻² with 3.5 mV kh⁻¹ decay) at low iridium loading (0.28 mgIr cm⁻²).
Conclusions:
- Confinement-engineered Ir─IrO2 interfaces effectively activate the oxide pathway mechanism (OPM) for acidic OER.
- The hydrogen-bond-mediated OPM (HB-OPM) is a key mechanism for designing durable, low-iridium acidic OER catalysts.
- This strategy offers a promising pathway for advancing efficient and stable PEMWE technology.
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