Everything, everywhere, all at once

Converting carbon dioxide (CO₂) into valuable chemicals through electrolysis offers a promising way to make use of excess CO₂ emissions from industrial processes. Among the various technologies being explored, membrane–electrode assembly (MEA)-based systems stand out for their efficiency and scalability, making them strong candidates for future industrial applications to make artificial fuels or CO₂-to-CO conversion. However, MEAs’ long-term stability remains a key challenge, and the degradation mechanisms of catalysts and electrodes in MEAs are not yet understood.

So far, researchers have achieved CO production at current densities over 1 A/cm² and device stability lasting more than 3,000 hours. These advances are fueling commercial interest—but also highlight a new challenge: long-term testing under standard conditions is too slow to support fast development.

“The performance of a CO₂ electrolysis can be determined in an hour, but 100s of hours are now needed for stability analysis.  The lack of a more efficient durability testing procedure is hampering our ability to most effectively use R&D resources”, says Brian Seger, professor at DTU and co-corresponding author of the publication. And first author Qiucheng Xu adds: “We need accelerated methods to mimic long-term operation and gain similar insights in a shorter timeframe."

New characterisation platform

The team from DTU, Twelve and the ESRF have now set up a new synchrotron X-ray characterisation platform to track the time- and space-resolved evolution of ions and water movement, crystal structure, and catalyst variations in MEAs during accelerated testing.

“This challenging problem must be tackled from various perspectives. We have developed a strong combination of operando X-ray techniques and chemical analyses, which can reveal the true complexity of the degradation mechanisms”, says Jakub Drnec, scientist in charge of beamline ID31, where the new suite of techniques take place, and co-corresponding author of the publication.

Specifically, they use Wide-Angle X-ray Scattering (WAXS), small-angle X-ray scattering (SAXS) and X-ray fluorescence (XRF) techniques on beamline ID31, all at once. The combined analysis of WAXS and SAXS enables the observation of the dynamic evolution of catalyst particle, allowing for differentiation between particle ripening and agglomeration. The inclusion of XRF facilitates monitoring of the cation distribution, which provides insight into whether cation concentration contributes to device operation and degradation.

The combination of these three techniques allows the researchers to more accurately isolate key physical phenomena, thereby bridging the gap between fundamental science and practical applications.

The team used gold and silver nanoparticle catalysts to test their new methodology. The results show that catalyst crystalline phase stability and nanoparticles-substrate adhesion strength are the key factors governing catalyst durability during CO₂ electrolysis.

In the case of gold, the catalyst keeps its crystal structure and nanoparticle distribution, and does not suffer degradation. However, this is not the case for the silver catalyst, which, in turn, is less stable and shows weak adhesion to the substrate, which translates into degradation over time.

“These advances in testing procedures are a testimony of a long-term collaboration between DTU and the ESRF to develop new methods to assist with the transition of electrolysers to commercialization”, concludes Brian Seger.

Reference:

Xu, Q., Zamora Zeledón, J.A., et al. Nat. Nanotechnol. (2025). https://doi.org/10.1038/s41565-025-01916-1

Text by Montserrat Capellas Espuny