In-Plane Conductivity as a Descriptor of Apparent Durability of RuO<sub>2</sub> Anodes in PEM Water Electrolysis.

Yang, Yongping; Sun, Hongmin; Li, Gong; Du, Henan; Song, Jiangnan; Zhang, Xueqiang; Chen, Yabin; Zhang, Shuailong et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

The apparent durability of proton exchange membrane water electrolyzers (PEMWEs) employing RuO<sub>2</sub> anodes varies significantly, even though RuO<sub>2</sub> is often used as a benchmark for Ru-based catalysts. We find that the in-plane conductivity effectively indicates key microstructural characteristics that govern the apparent durability. Low in-plane conductivity (e.g., <10 S cm<sup>-1</sup> in this study) limits electron transport and catalyst utilization while increasing susceptibility to electrochemical degradation. Only when in-plane conductivity is sufficiently high (above ∼25 S cm<sup>-1</sup> in this study) does apparent device durability reflect the intrinsic electrochemical stability of RuO<sub>2</sub> catalysts. Increasing the isopropanol ratio in the catalyst ink or adding carbon black as a conductive additive markedly enhances in-plane conductivity, extending device durability from 10.7 to 63.5 h (5.9-fold) at 1 A cm<sup>-2</sup>. This work clarifies the origin of apparent stability discrepancies among RuO<sub>2</sub> catalysts in PEMWEs, identifying in-plane conductivity as a key structural descriptor for reliable durability assessment.