Scalable synthesis of twinned iridium nanorods via thioiridate-mediated thermal reduction for efficient oxygen evolution

초록

Developing efficient and durable Ir-based catalysts for the oxygen evolution reaction (OER) in acidic media remains challenging, as their synthesis requires precise engineering to control atomic defects and macroscopic morphology, which often hinders large-scale production. Here, we report a rational synthesis of twinned Ir nanorod electrocatalysts via molecular-precursor engineering of thioiridate for efficient OER. Its optimal thermal reduction process induced selective desorption of sulfur species from specific Ir crystal facets, thereby directing the oriented attachment of Ir nanoparticles into one-dimensional nanorods. Moreover, this promoted oriented attachment creates multiple structural defects, such as twins and dislocations, along the attachment interfaces. These defect-rich Ir nanorods exhibited 0.473 A mgIr−1 at 1.55 V versus RHE, surpassing catalysts derived from commercial Ir/C by a factor of 2.2. The superior OER activity of the defect-rich Ir nanorods was further elucidated by theoretical calculations, which reveal that twin boundary regions serve as highly active sites that lower the free energy barriers of the OER-determining step. This work establishes thioiridate-mediated oriented attachment as a scalable, surfactant-free route for engineering high-performance Ir-based electrocatalysts for green hydrogen production. © 2026 Elsevier B.V.

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