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<p>Proton exchange membrane water electrolyzers face challenges due to high iridium loading and sluggish oxygen evolution reaction kinetics when using conventional rutile-structured iridium oxide nanocatalysts. Here we find that iridium oxide catalysts with a specific tunnel-type crystal structure exhibit highly localized reactivity, where regions at tunnel mouths drive oxygen evolution far more efficiently than tunnel-wall regions. The intrinsic activity of tunnel mouths is 25-fold higher than that of tunnel walls, with shorter nanorods achieving a better balance between active site exposure and electron/mass transport efficiency. When implemented in proton exchange membrane water electrolyzers, this engineered catalyst achieves notable performance at low iridium loading (0.28 mg<sub>Ir</sub> cm<sup>−2</sup>), delivering over 2.0 A cm<sup>−2</sup> at 1.8 V (80 °C) and operating stably for 1800 h—notably outperforming conventional catalysts. Our work identifies catalytic hotspots in tunnel-structured oxides and demonstrates their rational integration into high-performance, durable electrolyzer systems.</p>

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Tunnel-structured IrOx unlocks catalytic efficiency in proton exchange membrane water electrolyzers

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月15日

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  • Mingcheng Zhang,
  • Wei An,
  • Qianqian Liu,
  • Yuzhu Jiang,
  • Xiao Zhao,
  • Hui Chen,
  • Yongcun Zou,
  • Xiao Liang,
  • Xiaoxin Zou

摘要

Proton exchange membrane water electrolyzers face challenges due to high iridium loading and sluggish oxygen evolution reaction kinetics when using conventional rutile-structured iridium oxide nanocatalysts. Here we find that iridium oxide catalysts with a specific tunnel-type crystal structure exhibit highly localized reactivity, where regions at tunnel mouths drive oxygen evolution far more efficiently than tunnel-wall regions. The intrinsic activity of tunnel mouths is 25-fold higher than that of tunnel walls, with shorter nanorods achieving a better balance between active site exposure and electron/mass transport efficiency. When implemented in proton exchange membrane water electrolyzers, this engineered catalyst achieves notable performance at low iridium loading (0.28 mgIr cm−2), delivering over 2.0 A cm−2 at 1.8 V (80 °C) and operating stably for 1800 h—notably outperforming conventional catalysts. Our work identifies catalytic hotspots in tunnel-structured oxides and demonstrates their rational integration into high-performance, durable electrolyzer systems.