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<p>Herein, spin regulation of the low-spin Ir<sup>4+</sup> in Ca<sub>2</sub>IrO<sub>4</sub> is realized via a novel spin balance strategy through a Janus Ir–Co structure using high-spin Co<sup>3+</sup> dopants, achieving the intermediate-spin state of Ir and Co atoms and enhancing the acidic oxygen evolution reaction (OER) performance of the obtained catalysts (Co–CIO). The optimized 0.2Co–CIO catalyst, with a nominal Co/(Co + Ir) metal atom percentage of 20%, displays exceptional electrochemical water oxidation activity with an ultrasmall overpotential of ~ 200&#xa0;mV at 10&#xa0;mA&#xa0;cm<sup>−2</sup>, ultralarge mass activity of 1110 A g<sub>Ir</sub><sup>−1</sup>, and high turnover frequency of 2050&#xa0;h<sup>‒1</sup> under an overpotential of 300&#xa0;mV in 1&#xa0;M HClO<sub>4</sub>, outperforming most recently reported Ir–based oxides catalysts. Molecular and atomic characterizations via in situ X-ray absorption near-edge and Raman spectroscopy demonstrate the acceleration of bridged O‒O formation over the Janus Ir–Co units, indicating a preference for the superoxide path mechanism for Co–CIO. Furthermore, density functional theory calculations rationalize the promotion of the superoxide *O‒O intermediate over the spin-regulated Ir‒O‒Co units, thanks to optimized <i>e</i><sub>g</sub><sup>1</sup> orbital and reduced <i>t</i><sub>2g</sub> orbital occupancy. The study presents a rare example of Ir spin regulation via a Janus Ir–Co magnetic structure, thereby promoting acidic OER activity. </p>

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Spin Balance Over Janus Ir-Co Magnetic Atoms for Efficient Acidic Water Oxidation

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月28日

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  • Na Li,
  • Weiren Cheng,
  • Yuying Liu,
  • Ruiqi Liu,
  • Sihua Feng,
  • Huijuan Wang,
  • Liyang Lv,
  • Chenglong Liu,
  • Jin Ma,
  • Chao Wang,
  • Wensheng Yan

摘要

Herein, spin regulation of the low-spin Ir4+ in Ca2IrO4 is realized via a novel spin balance strategy through a Janus Ir–Co structure using high-spin Co3+ dopants, achieving the intermediate-spin state of Ir and Co atoms and enhancing the acidic oxygen evolution reaction (OER) performance of the obtained catalysts (Co–CIO). The optimized 0.2Co–CIO catalyst, with a nominal Co/(Co + Ir) metal atom percentage of 20%, displays exceptional electrochemical water oxidation activity with an ultrasmall overpotential of ~ 200 mV at 10 mA cm−2, ultralarge mass activity of 1110 A gIr−1, and high turnover frequency of 2050 h‒1 under an overpotential of 300 mV in 1 M HClO4, outperforming most recently reported Ir–based oxides catalysts. Molecular and atomic characterizations via in situ X-ray absorption near-edge and Raman spectroscopy demonstrate the acceleration of bridged O‒O formation over the Janus Ir–Co units, indicating a preference for the superoxide path mechanism for Co–CIO. Furthermore, density functional theory calculations rationalize the promotion of the superoxide *O‒O intermediate over the spin-regulated Ir‒O‒Co units, thanks to optimized eg1 orbital and reduced t2g orbital occupancy. The study presents a rare example of Ir spin regulation via a Janus Ir–Co magnetic structure, thereby promoting acidic OER activity.