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Abstract An improved understanding of catalyst dynamics for the oxygen evolution reaction (OER) in acid is critical for informing the development of highly efficient, stable, and cost‐effective OER catalysts for proton exchange membrane water electrolysis applications. Herein highly tunable, active, and dynamic Ir 5+ materials are studied, Ln3IrO7(Ln = Pr, Nd, Sm, and Eu). Leveraging a combination of in situ and ex situ characterization, as well as an advanced mercury underpotential deposition technique for Ir surface site quantification, the dynamic nature of Ln3IrO7materials throughout electrochemical activation under OER conditions is characterized. The trends are elucidated between intrinsic OER activity, surface Ir site quantity, and metal site dissolution behavior as tuned by the Ln site's atomic number. A critical relationship is uncovered to show that maintenance of excellent OER activity throughout performance testing is correlated with a catalysts’ ability to preserve a high degree of Ir enrichment, where heightened stability of Ir sites interestingly parallels reduced stability of Ln sites throughout testing. It is found that as the Ln site's atomic number is decreased, the materials’ intrinsic OER performance improves, due to an increased thermodynamic driving force for Ln dissolution, which is hypothesized to enable the maintenance of highly active Ir‐based surface motifs.
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This content will become publicly available on August 1, 2026
Emergent Epitaxial Configuration of Pr 3 IrO 7 Domains via YSZ (111) Substrate
The 5drare Earth iridate is an intriguing material with exhibiting exotic electronic and magnetic phases due to spin‐orbit coupled states. Ternary iridium oxidesLn3IrO7contain an unusual Ir5+(5d4) system, which remain a subject of active research. Fabricating epitaxialLn3IrO7films is challenging due to substrate compatibility, but it offers a valuable platform to explore electronic and magnetic behaviors under reduced dimensionality and substrate interactions, revealing novel phenomena based on Ir5+(5d4). In this regard, this demonstrates that Pr3IrO7with its highly anisotropic orthorhombic structure can be epitaxially grown on a cubic (111)‐oriented yttrium‐stabilized ZrO2(YSZ) substrate. Pr3IrO7film exhibits six epitaxial domains, where the (220) and (202) planes aligning epitaxially to YSZ (111) with the threefold symmetry. This diverse domain configuration in Pr3IrO7film leads to unique magnetic properties, exhibiting spin‐glass‐like behavior. Pr3IrO7thin film offers a platform for exploring unconventional magnetic states, and their successful heteroepitaxy on YSZ substrates opens new avenues for discovering novel physical phenomena.
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- Award ID(s):
- 2309000
- PAR ID:
- 10637868
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Small Structures
- Volume:
- 6
- Issue:
- 8
- ISSN:
- 2688-4062
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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