Journal Article

PUBDB-2025-05277

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Shaping low-iridium IrRuO$_x$ electrocatalysts with structural and electronic modulation for proton exchange membrane electrolyzers

Sadeghi, E. ; Karlsen, M. A.DESY* ; Karimi, V. ; Maynau, C. ; Morgen, P. ; Sharma, R. (Corresponding author) ; Lajaunie, L. ; Andersen, S. M. (Corresponding author)

2025
RSC London, United Kingdom

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Please use a persistent id in citations: doi:10.1039/D5TA07594G  doi:10.3204/PUBDB-2025-05277

Abstract: Reducing iridium (Ir) loading without compromising the stability of the oxygen evolution reaction (OER) activity is essential for the sustainable deployment of proton exchange membrane (PEM) electrolyzers. One promising approach is the development of Ir-based mixed oxides, such as Ir–Ru systems, which harness synergistic effects to enhance activity and durability beyond that of IrO$_x$ benchmarks. Here, we report a unique high-performance IrRuO$_x$ catalyst synthesized via a straightforward solid-state molten-salt method. Structural characterization employing both synchrotron and in-house XRD revealed lattice contraction in IrRuO$_x$ relative to IrO$_x$/i></sub>, which hinted a solid-solution formation. X-ray photoelectron spectroscopy confirmed higher oxidation states of Ru in Ir$_{0.25}$Ru$_{0.75}$O$_x$ compared to RuO$_x$, which is correlated with its enhanced electrochemical performance. Electron microscopy studies showed the formation of 2D nanosheets rich in grain boundaries (GBs), which facilitate charge transport and stabilize active sites. Pair distribution function (PDF) analysis revealed the coexistence of rutile and hollandite phases, with hollandite content decreasing at higher synthesis temperatures and with increasing Ru content. As an anode in a proton exchange membrane electrolyzer, Ir$_{0.25}$Ru$_{0.75}$O$_x$ demonstrated superior performance and delivered 1 A cm$^{−2}$ at 1.69 V with only ∼0.3 mg$_{Ir}$ cm$^{−2}$—outperforming commercial IrO$_2$ (1.75 V) and IrRuO$_x$(1.77 V) under similar conditions.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. PETRA-D (FS-PETRA-D)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)

Experiment(s):

1. PETRA Beamline P02.1 (PETRA III)

Appears in the scientific report 2025

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 10 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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