Regulating Ru-Ru Distance in RuO<sub>2</sub> Catalyst by Lattice Hydroxyl for Efficient Water Oxidation.

She, Sixuan; Chen, Hsiao-Chien; Chen, Changsheng; Zhu, Yanping; Chen, Gao; Song, Yufei; Xiao, Yiping; Lin, Zezhou et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Highly active and durable electrocatalysts for the oxygen evolution reaction (OER) are crucial for proton exchange membrane water electrolysis (PEMWE). While doped RuO<sub>2</sub> catalysts demonstrate good activity and stability, the presence of dopants limits the number of exposed active sites and complicates Ru recovery. Here, we present a monometallic RuO<sub>2</sub> (d-RuO<sub>2</sub>) with lattice hydroxyl in the periodic structure as a high-performance OER electrocatalyst. The obtained d-RuO<sub>2</sub> catalyst exhibits a low overpotential of 150 mV and long-term operational stability of 500 h at 10 mA cm<sup>-2</sup>, outperforming many Ru/Ir-based oxides ever reported. A PEMWE device using d-RuO<sub>2</sub> sustains operation for 348 h at 200 mA cm<sup>-2</sup>. In-situ characterization reveals that the incorporation of lattice hydroxyl increases the Ru-Ru distance, which facilitates the turnover of the Ru oxidation state and promotes the formation of stable edge-sharing [RuO<sub>6</sub>] octahedra during the OER, thereby accelerating the formation of O-O bonds and suppressing the overoxidation of Ru sites. Additionally, the small particle size of the catalyst decreases the three-phase contact line and promotes bubble release. This study will provide insights into the design and optimization of catalysts for various electrochemical reactions.