Electrochemical surface composition of iridium oxide IrO2(110): Implications for the oxygen evolution reaction mechanism

Document Type

Article

Source Title

ACS Omega

Publication Date

2025

Abstract

The mechanism of the Oxygen Evolution Reaction (OER) on iridium oxide IrO2(110) highly depends on the stable structure of the surface under various electrochemical conditions. Through a first-principles-based Pourbaix diagram, we identified the stable di- and trioxygen surface terminations of IrO2(110) at electrode potentials relevant to the OER. Thermodynamics calculations revealed that the OER proceeds at an electrode potential where the surface is terminated with a hydrotrioxide species (−IrOOOH), which electrochemically decomposes to produce an oxygen gas. Our results point to a cyclic OER mechanism that is electrode potential-limited by the electrochemical dissociation of water to regenerate the hydrotrioxide-terminated surface. These findings provide new insights into the role of the initial surface composition of the catalyst in the reaction mechanism of the OER.

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Digitial Object Identifier (DOI)

https://doi.org/10.1021/acsomega.5c10410

Disciplines

Chemistry

Keywords

Oxygen; Iridium oxide; Surfaces (Technology)

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