# In Situ and Operando Insights into the Oxygen Evolution Reaction Activity and Stability of Nanometer-Sized Rutile Iridium Oxides

Frédéric Maillard, Michal Ronovský, Delphine Clauss, Vincent Martin,

Thomas Hrbek, Miquel Gamón Rodríguez, Pieter Kúš, Meryem Ennaji,

Raphaël Chattot, Jakub Drnec, et al.

► To cite this version:

Frédéric Maillard, Michal Ronovský, Delphine Clauss, Vincent Martin, Thomas Hrbek, et al. In Situ and Operando Insights into the Oxygen Evolution Reaction Activity and Stability of Nanometer-Sized Rutile Iridium Oxides. 6th edition of the Power Our Future (POF) International Forum, CIC Energune, Jul 2025, Vitoria-Gasteiz, Spain. hal-05253233

HAL Id: hal-05253233

https://hal.science/hal-05253233v1

Submitted on 13 Sep 2025

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# *In Situ* and *Operando* Insights into the Oxygen Evolution Reaction Activity and Stability of Nanometer-Sized Rutile Iridium Oxides

F. Maillard<fnref n="1" />, M. Ronovský<fnref n="1" />, D. Clauss<fnref n="1" />, V. Martin<fnref n="1" />, T. Hrbek<fnref n="2" />, M. Gamón Rodríguez<fnref n="2" />, P. Kúš<fnref n="2" />, M. Ennaji<fnref n="3" />, R. Chattot<fnref n="3" />, J. Drnec<fnref n="4" />, B. Iskandarani<fnref n="5" />, I. Zenyuk<fnref n="5" />, L. Dubau<fnref n="1" />

The high investment cost of proton-exchange membrane water electrolyzers (PEMWEs) partly stems from their constituting materials<fnref n="1" />. Research efforts thus aim to reduce the loading of iridium oxide (IrOₓ) used for catalyzing the oxygen evolution reaction (OER) at the anode. Downsizing IrOₓ particles is a promising strategy, but the Gibbs-Thomson effect challenges its feasibility due to stability concerns.

In this contribution, I will review our research efforts in this direction. I will show that supported IrOₓ nanocatalysts tend to be more active for the OER but less stable than unsupported micrometer-sized ones<fnref n="2" />. Much of this instability arises from metal oxide supports, which corrode or loose doping and cause nanoparticle detachment or electrical disconnection<fnref n="3" />, <fnref n="4" />. I will then present our recent advances in synthesizing self-standing IrO₂ nanoparticles, and show how they can serve as model catalysts for probing OER activity-stability relationships or enhancing PEMWE performance<fnref n="5" />. The role of advanced *in situ* or *operando* techniques will be emphasized. Finally, I will outline remaining challenges, such as precious metal recycling, to enable broader PEMWE adoption⁶.

This work was supported by the "France 2030" government investment plan managed by the French National Research Agency, under the reference "ANR-22-PEHY-0011", in the frame of the MATHYLDE project.

## References:

¹ C. R. Wang, J. M. Stansberry, et al., *Chem. Rev.* 2025, **125**(3), 1257-1302.

² C. Daiane Ferreira da Silva, F. Claudel, et al., *ACS Catal.* 2021, **11**(7), 4107-4116.

³ F. Claudel, L. Dubau, G. Berthomé, L. Sola-Hernandez, C. Beauger, L. Piccolo, F. Maillard. *ACS Catal.* 2019, **9**(5), 4688-4698.

⁴ S. Abbou, R. Chattot, V. Martin, F. Claudel, L. Solà-Hernandez, C. Beauger, L. Dubau, F. Maillard. *ACS Catal.* 2020, **10**(13), 7283-7294.

⁵ D. Clauss, V. Martin, J. Nelayah, R. Chattot, P. Bordet, J. Drnec, M. Mirolo, L. Dubau, F. Maillard. *ACS Catal.* 2025, **15**(3), 2654-2665.

⁶ S. Turnbull, D. Clauss, V. Martin, J. P. Magnin, L. Dubau, F. Maillard. *RSC Sustainability.* 2025, **3**, 1741-1750.

<footnote n="1">¹ Univ. Grenoble Alpes, Univ. Savoie-Mont-Blanc, CNRS, Grenoble-INP, LEPMI, 38000 Grenoble, France</footnote>

<footnote n="2">² Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 180 00, Prague 8, Czech Republic</footnote>

<footnote n="3">³ ICGM, Univ. Montpellier, CNRS, ENSCM, Montpellier 34095 Cedex 5, France</footnote>

<footnote n="4">⁴ ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France</footnote>

<footnote n="5">⁵ Department of Chemical and Biomolecular Engineering, National Fuel Cell University of California Irvine, Irvine, CA, USA</footnote>