The impact of metallic impurities on the activity-stability relationship of iridium-based nanofiber catalysts for acidic water electrolysis

Kovács MM, Mayrhofer KJ, Dworschak D (2025)


Publication Type: Journal article

Publication year: 2025

Journal

Book Volume: 179

Article Number: 108011

DOI: 10.1016/j.elecom.2025.108011

Abstract

PEM water electrolyzers are operated with deionized or highly purified water. However, metallic impurities can appear in the pipes as well as in the inner compartment due to corrosion of the metal parts of the electrolyzer cell as the bipolar plate (BPP) or the porous transport layer (PTL). The dissolved ions from the cell components have an influence on the degradation and may impact the catalyst activity. Our objective is to shed light on these processes in the case of two selected metal ion contaminations, which helps us understand the relevance of selecting proper catalyst materials for acidic water splitting. In this study, the impact of cationic impurities on the electrocatalytic activity and stability of IrOx based nanofiber catalyst materials for acidic water electrolysis is investigated in a scanning flow cell coupled with an inductively coupled plasma mass spectrometer (SFC-ICP-MS). IrOx catalyst materials are tested in an aqueous model system of 0.1 M HClO4 containing 5 ppm (molar ratio) Fe3+ and Al3+. The reference IrOx Alfa Aesar (AA) shows a significant increase in oxygen evolution reaction (OER) activity, while IrOx calcined at 400 °C suffers from an activity decline of more than 50% if 5 ppm Fe3+ are in the electrolyte. Due to their high iridium oxide content, IrOx species calcined at 600 °C and 800 °C exhibit no significant change regardless of the contaminant ion introduced. In terms of the stability number (S-number), the dissolution rate of the 400 °C species can be mitigated by Fe3+ ions, while it influenced the other catalysts only modestly. This is mainly the case for Al3+ ions, although a slight enhancement can be observed for the highly oxidized species of 600 °C and 800 °C. In general, the presence of Fe3+ and Al3+ ions has a controversial influence on the OER activity and the degradation of iridium-based catalyst materials, which is mainly driven by their oxidation state.

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How to cite

APA:

Kovács, M.M., Mayrhofer, K.J., & Dworschak, D. (2025). The impact of metallic impurities on the activity-stability relationship of iridium-based nanofiber catalysts for acidic water electrolysis. Electrochemistry Communications, 179. https://doi.org/10.1016/j.elecom.2025.108011

MLA:

Kovács, Miklós Márton, Karl J.J. Mayrhofer, and Dominik Dworschak. "The impact of metallic impurities on the activity-stability relationship of iridium-based nanofiber catalysts for acidic water electrolysis." Electrochemistry Communications 179 (2025).

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