Accelerated Iridium Dissolution in Proton Exchange Membrane (PEM) Water Electrolyzers by Inert Mobile Anions Adsorbed in the Double Layer

Journal of The Electrochemical Society, vol. 172, pp. 064509

Abstract

Iridium oxides display state-of-the-art electrocatalysts for anodes in proton exchange membrane water electrolyzers (PEM-WE), combining electrocatalytic activity for the oxygen evolution reaction (OER) and reasonable stability. During OER with liquid electrolytes, iridium dissolution rates were reported as orders of magnitude higher than those of operating PEM-WE cells, while the reasons for these differences are not well understood. Here, iridium oxide dissolution in an operating PEM-WE cell is examined with different feeds, including pure water, 0.1 M sulfuric acid, and 0.1 M perchloric acid. With sulfuric acid feed, the electrically contacted iridium oxide at the anode is found to dissolve within 22 h. In comparison, the dissolution rates with perchloric acid addition and pure water are approximately 120 and 1500 times smaller, respectively. These differences are explained with a novel theory that correlates the influence of inert mobile anions on dissolution rates by their adsorption in the electrochemical double layer. This physicochemical effect also explains previously reported discrepancies of reported iridium dissolution rates with different electrolytes. Based on the results, the quality of the feed water in terms of inert anion pollution is highlighted as a critical factor for achieving long life of PEM-WE cells with low iridium loadings.

Authors 9

1. Maximilian Schalenbach corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

2. Niklas L. Wolf corresponding Aachen Institute of Physical Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

3. Jean‐Pierre Poc corresponding Aachen Institute of Physical Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

4. Christine Heume corresponding Aachen Institute of Physical Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

5. Shibabrata Basak corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

6. Roland Schierholz corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

7. André Karl corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

8. Eva Jodat corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

9. Rüdiger‐A. Eichel corresponding Aachen Institute of Physical Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Technologies (IET-1): Fundamental Electrochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany