The origin of the high electrochemical activity of pseudo-amorphous iridium oxides



Elmaalouf, Marine, Odziomek, Mateusz, Duran, Silvia, Gayrard, Maxime, Bahri, Mounib ORCID: 0000-0002-8336-9158, Tard, Cedric, Zitolo, Andrea, Lassalle-Kaiser, Benedikt, Piquemal, Jean-Yves, Ersen, Ovidiu
et al (show 5 more authors) (2021) The origin of the high electrochemical activity of pseudo-amorphous iridium oxides. NATURE COMMUNICATIONS, 12 (1). 3935-.

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Abstract

Combining high activity and stability, iridium oxide remains the gold standard material for the oxygen evolution reaction in acidic medium for green hydrogen production. The reasons for the higher electroactivity of amorphous iridium oxides compared to their crystalline counterpart is still the matter of an intense debate in the literature and, a comprehensive understanding is needed to optimize its use and allow for the development of water electrolysis. By producing iridium-based mixed oxides using aerosol, we are able to decouple the electronic processes from the structural transformation, i.e. Ir oxidation from IrO<sub>2</sub> crystallization, occurring upon calcination. Full characterization using in situ and ex situ X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy allows to unambiguously attribute their high electrochemical activity to structural features and rules out the iridium oxidation state as a critical parameter. This study indicates that short-range ordering, corresponding to sub-2nm crystal size for our samples, drives the activity independently of the initial oxidation state and composition of the calcined iridium oxides.

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Engineering
Depositing User: Symplectic Admin
Date Deposited: 20 Dec 2021 15:38
Last Modified: 18 Jan 2023 21:18
DOI: 10.1038/s41467-021-24181-x
Open Access URL: https://www.nature.com/articles/s41467-021-24181-x
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3145703