Degradation of IrOx Nanoparticles Supported Onto Sb-Doped SnO2 Aerogel Monitored By Dynamic Electrochemical Impedance Spectroscopy and Identical-Location TEM

Abstract : Supporting metal nanoparticles is a common approach in heterogeneous gas-phase catalysis to decrease the metal loading, prevent agglomeration and thus minimize the cost of a catalytic conversion. This approach proved particularly successful in proton-exchange membrane fuel cells (PEMFC) where the replacement of Pt-blacks (used in early PEMFCs) by carbon-supported Pt nanoparticles has significantly improved the Pt specific power density. Using the same material’s concepts in proton-exchange membrane water electrolysers (PEMWE) could minimize the noble metal loading especially at the anode where the oxygen evolution reaction (OER) takes place. However, high-surface area carbon supports are rapidly degraded in the operating conditions of a PEMWE anode (E > 1.6 V vs. the reversible hydrogen electrode, T = 80 °C) calling for alternative support materials. In this contribution, IrOx nanoparticles were synthesized using the polyol method and deposited onto antimony doped tin dioxide aerogel (ATO) or Vulcan XC-72 (as a reference), and tested as OER electrocatalysts. By combining classical electrochemical techniques, dynamic Electrochemical Impedance Spectroscopy (dEIS) and Identical-Location Transmission Electron Microscopy (IL-TEM), we gained some insights into the mechanisms leading to loss of OER activity. IL-TEM images (Figure 1) provide strong evidence that the activation step was detrimental to the ATO support while no major degradation was observed at higher voltages (OER region). Approximately 73 % of the initial activity was lost for IrOx/ Vulcan XC-72 after 4,000 potential cycles between 1.2 and 1.6 V vs. the reversible hydrogen electrode (RHE) compared to 16 % for IrOx/ATO. The polarization resistance measured in the OER region by dEIS remains roughly the same for IrOx/ATO while a large increase was observed for IrOx/Vulcan XC-72.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-01973280
Contributeur : Magalie Prudon <>
Soumis le : mardi 8 janvier 2019 - 11:25:23
Dernière modification le : lundi 7 octobre 2019 - 12:34:04

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  • HAL Id : hal-01973280, version 1

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Fabien Claudel, Laetitia Dubau, Svein Sunde, Guillaume Ozouf, Christian Beauger, et al.. Degradation of IrOx Nanoparticles Supported Onto Sb-Doped SnO2 Aerogel Monitored By Dynamic Electrochemical Impedance Spectroscopy and Identical-Location TEM. 233rd ECS MEETING, The Electrochemical Society, May 2018, Seattle, United States. ⟨hal-01973280⟩

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