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Revealing the reactivity of the Iridium trioxide intermediate for the oxygen evolution reaction in acidic media

preprint
submitted on 25.04.2019 and posted on 29.04.2019 by Paul Pearce, Chunzhen Yang, Antonella Iadecola, Juan Rodriguez-Carvajal, Gwenaëlle Rousse, Rémi Dedryvère, Artem M. Abakumov, Domitille Giaume, Michael Deschamps, Jean-Marie Tarascon, Alexis Grimaud
We report a strategy to isolate IrO3 as an intermediate for the oxygen evolution reaction (OER). Its reactivity is studied using X-ray absorption spectroscopy, X-ray and neutron diffraction and X-ray photoelectron spectroscopy. Its stability is assessed by using on-line mass spectroscopy and inductively coupled plasma optical emission spectroscopy and presented herein. Upon reaction with water in acidic conditions, we could observe the formation of a new protonated iridate phase of composition H2IrO3. Coupling OER measurements and dissolution rate determination, we could show that its activity and stability are governed by a yet ill-described charge compensation mechanism enlisting reversible bulk proton insertion inside the catalyst structure. This singular property enables an enhanced activity and stability towards dissolution compared to the stellar IrOx/SrIrO3 catalyst. Such a finding opens the route towards the design of new OER catalysts enlisting proton insertion that could be competitive for water splitting in acidic media.

Funding

ERC Grant-Project 670116-ARPEMA

History

Email Address of Submitting Author

alexis.grimaud@college-de-france.fr

Institution

Collège de France

Country

France

ORCID For Submitting Author

0000-0002-9966-205X

Declaration of Conflict of Interest

There are no conflicts to declare.

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