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Stability of electrocatalysts for water splitting

Iridium oxide is the state-of-the-art electrocatalyst for the oxygen evolution reaction in water electrolyzers, as it combines good activity with excellent stability. However, the crustal abundance of iridium is very low. Therefore, the large-scale use of water electrolyzers will be possible only if the iridium loading is significantly decreased and the intrinsic activity of IrO2 is maximized. The latter is possible by alloying IrO2 with RuO2, but the inferior stability of ruthenium is a problem for the use of iridium-ruthenium mixed oxides in a real system. We utilized the SFC-ICP-MS couple to determine whether there is a region of RuO2 compositions that allows activitiy enhancement without being detrimental for the catalyst stability. The SFC-ICP-MS couple allows the simultaneous detection of iridium and ruthenium when dissolved from Ir-Ru material libraries of gradient composition, under the oxygen evolution condtions. The gradients were prepared in-house, using physical vapor deposition (PVD) equipped with two sputtering targets.

Stability of electrocatalysts for water splittingSchematic illustration of gradient Ir-Ru oxide libraries studied by SFC-ICP-MS and results showing potential-resolved dissolution of Ru and Ir as a function of film composition.
Copyright: Dr. Olga Kasian/Max-Planck-Institut für Eisenforschung GmbH

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