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<p>Highly active and stable oxygen evolution reaction (OER) catalysts are needed because OER in acidic media requires considerable energy input. In this work, the hydrolysis of Mn<sup>2+</sup> is promoted through tuned thermal decomposition of urea, generating uniformly dispersed Mn(OH)<sub>2</sub> colloids. In the presence of these freshly formed colloids, IrCl<sub>3</sub> is converted into [Ir(OH)<sub>6</sub>]<sup>3−</sup> under alkaline conditions. Subsequent dropwise addition of nitric acid transforms [Ir(OH)<sub>6</sub>]<sup>3−</sup> into Ir(OH)<sub>3</sub>(H<sub>2</sub>O)<sub>3</sub> on the Mn(OH)<sub>2</sub> surfaces, yielding a precursor powder that is thermally treated to produce Ir<sub>7</sub>Mn<sub>3</sub>O<sub>X</sub>-200 catalysts with an average particle size of approximately 1.4&#xa0;nm. The catalysts show strong OER performance, achieving a mass activity of 1.27&#xa0;A&#xa0;mg<sup>−1</sup> at 1.6&#xa0;V and an overpotential of 304&#xa0;mV at 10&#xa0;mA&#xa0;cm<sup>−2</sup>. Chrono-potentiometric and chrono-amperometric measurements confirm excellent stability, with only a ~ 23&#xa0;mV increase in potential after 2&#xa0;h of operation at 10&#xa0;mA&#xa0;cm<sup>−2</sup>. Ultraviolet–visible spectroscopy provides mechanistic insight into the formation of the catalyst precursor.</p> Graphical abstract <p></p>

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Oxygen evolution reaction performance and synthesis process mechanism on Mn-doped Ir7Mn3OX catalysts via tuned urea thermal hydrolysis

  • 期刊论文

  • 发表日期：

    2025年12月12日

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  • Yuexia Li,
  • Lei Wu,
  • Hang Zhan,
  • Caiting Ji,
  • Yan Sun,
  • Zhiyi Zhang,
  • Jianhuang Zeng

摘要

Highly active and stable oxygen evolution reaction (OER) catalysts are needed because OER in acidic media requires considerable energy input. In this work, the hydrolysis of Mn2+ is promoted through tuned thermal decomposition of urea, generating uniformly dispersed Mn(OH)2 colloids. In the presence of these freshly formed colloids, IrCl3 is converted into [Ir(OH)6]3− under alkaline conditions. Subsequent dropwise addition of nitric acid transforms [Ir(OH)6]3− into Ir(OH)3(H2O)3 on the Mn(OH)2 surfaces, yielding a precursor powder that is thermally treated to produce Ir7Mn3OX-200 catalysts with an average particle size of approximately 1.4 nm. The catalysts show strong OER performance, achieving a mass activity of 1.27 A mg−1 at 1.6 V and an overpotential of 304 mV at 10 mA cm−2. Chrono-potentiometric and chrono-amperometric measurements confirm excellent stability, with only a ~ 23 mV increase in potential after 2 h of operation at 10 mA cm−2. Ultraviolet–visible spectroscopy provides mechanistic insight into the formation of the catalyst precursor.

Graphical abstract