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<p>Iridium has the exclusive chemistry guaranteeing both high catalytic activity and sufficient corrosion resistance in a strong acidic environment under anodic potential. Complex iridates thus attract considerable attention as high-activity electrocatalysts with less iridium utilization for the oxygen evolution reaction (OER) in water electrolyzers using a proton-exchange membrane. Here we demonstrate the effect of chemical doping on the durability of hexagonal-perovskite Ba<sub><i>x</i></sub>(M,Ir)<sub><i>y</i></sub>O<sub><i>z</i></sub>-type iridates in strong acid (pH ~ 0). Some aliovalent cations are directly visualized to periodically locate at the octahedral sites bridging the two face-sharing [Ir<sub>2</sub>O<sub>9</sub>] dimer or [Ir<sub>3</sub>O<sub>12</sub>] trimers in hexagonal-perovskite polytypes. In particular, highly ionic bonding of the <i>d</i><sup>0</sup> Nb<sup>5+</sup> and Ta<sup>5+</sup> cations with oxygen anions results in notable suppression of lattice oxygen participation during the OER and thus effectively preserves the connectivity between the [Ir<sub>3</sub>O<sub>12</sub>] trimers without lattice collapse. Providing an in-depth understanding of the correlation between the electronic structure and bonding nature in crystals, our work suggests that proper control of chemical doping in complex oxides promises a simple but efficient tool to realize OER electrocatalysts with markedly improved durability.</p>

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Effect of ionic-bonding d0 cations on structural durability in barium iridates for oxygen evolution electrocatalysis

  • 期刊论文

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  • 发表日期：

    2025年5月4日

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  • Yelyn Sim,
  • Tae Gyu Yun,
  • Ki Hyun Park,
  • Dongho Kim,
  • Hyung Bin Bae,
  • Sung-Yoon Chung

摘要

Iridium has the exclusive chemistry guaranteeing both high catalytic activity and sufficient corrosion resistance in a strong acidic environment under anodic potential. Complex iridates thus attract considerable attention as high-activity electrocatalysts with less iridium utilization for the oxygen evolution reaction (OER) in water electrolyzers using a proton-exchange membrane. Here we demonstrate the effect of chemical doping on the durability of hexagonal-perovskite Bax(M,Ir)yOz-type iridates in strong acid (pH ~ 0). Some aliovalent cations are directly visualized to periodically locate at the octahedral sites bridging the two face-sharing [Ir2O9] dimer or [Ir3O12] trimers in hexagonal-perovskite polytypes. In particular, highly ionic bonding of the d0 Nb5+ and Ta5+ cations with oxygen anions results in notable suppression of lattice oxygen participation during the OER and thus effectively preserves the connectivity between the [Ir3O12] trimers without lattice collapse. Providing an in-depth understanding of the correlation between the electronic structure and bonding nature in crystals, our work suggests that proper control of chemical doping in complex oxides promises a simple but efficient tool to realize OER electrocatalysts with markedly improved durability.