(Karlsruhe) – At the Karlsruhe Institute of Technology (KIT), researchers have investigated the processes on the surface of the iridium oxide catalyst for water electrolysis. Since the availability of electricity from renewable sources fluctuates, according to KIT, it is “very important to know the behavior of the catalysts under high load and under dynamic conditions.”
Measurements made difficult by oxygen bubbles
“At high currents, there is a strong development of oxygen bubbles on the anode, which makes the measurement more difficult and has so far made it almost impossible to obtain a reliable measurement signal,” explains the first author of the study, Steffen Czioska from the Institute for Technical Chemistry and Polymer Chemistry (ITCP). of KIT. The combination of various techniques now enabled the scientists to fundamentally research the surface of the iridium oxide catalyst under dynamic working conditions, according to a statement. “For the first time, we succeeded in studying the behavior of the catalyst at the atomic level despite strong bubble development,” says Czioska.
The researchers at ITCP, the Institute for Catalysis Research and the Institute for Applied Materials have combined X-ray absorption spectroscopy, which allows changes at the atomic level to be examined particularly precisely, and other analysis methods. In this way, you could see the regular processes on the catalyst surface during the reaction and recognize the dynamic processes because everything irregular was filtered out - "similar to a long exposure of a street at night," says Czioska. The investigations have shown that “especially at very high tensions and under dynamic conditions, highly unexpected structural changes occur that are associated with stabilization of the catalyst.” The iridium oxide dissolves less and the material remains stable.
Towards more efficient catalysts
Research into the processes paves the way for further investigation of catalysts at high electrical potentials and contributes to “developing improved and more efficient catalysts”. The study is part of the German Research Foundation's “Dynakat” priority program, in which over 30 research groups work together across Germany and is coordinated by KIT under the leadership of Jan-Dierk Grunwaldt from ITCP.
The research contribution to the development of improved and more efficient catalysts was awarded the ACS Editor's Choice by the American Chemical Society.
Steffen Czioska, Alexey Boubnov, Daniel Escalera-López, Janis Geppert, Alexandra Zagalskaya, Philipp Röse, Erisa Saraçi, Vitaly Alexandrov, Ulrike Krewer, Serhiy Cherevko, Jan-Dierk Grunwaldt: Increased Ir-Ir interaction in iridium oxide during the oxygen evolution reaction at high potentials probed by operando spectroscopy. ACS Catalysis, 2021. DOI: 10.1021/acscatal.1c02074
deep link
https://www.kit.edu/kit/pi_2021_077_gruner-wasserstoff-katalysatorenoberflache-im-blick.php
The Publication is available as a download (30 pages) in English at
https://pubs.acs.org/doi/abs/10.1021/acscatal.1c02074
Class schedule
Green hydrogen is considered a key element of the energy transition / © KIT / Pascal Armbruster
