Lecture

Van Marum Colloquium: Watching nanoparticles in action: Characterization of electrocatalysts with synchrotron X-ray techniques

• Dr. Rebecca Pittkowski (University of Copenhagen)

Date

Monday 16 October 2023

Time

16:00 - 17:00

Location

Gorlaeus Building
Einsteinweg 55
2333 CC Leiden

Room

DM0.13

Abstract

Electrocatalysis plays a major role in energy conversion technologies such as electrolyzers and fuel cells. Small nanoparticles, typically less than 10 nm in size, provide a high surface-to-bulk-atom ratio which is crucial for efficient utilization of the catalyst material, often based on scarce precious metals like Pt[1] and Ir.[2] However, these small nanoparticles suffer often from instability in electrochemical environments, and the underlying degradation mechanisms are, so far, not fully understood. In this context, synchrotron X-ray techniques are valuable tools for unraveling the catalyst's structural changes during operation. In-situ and operando experiments enable us to monitor the evolution of atomic structures. With small-angle X-ray scattering (SAXS), changes in size and morphology can be tracked,[3] while X-ray diffraction provides insights into the crystalline atomic structure.[1] This can provide valuable information on the mechanisms that dominate catalyst degradation and can help to devise new strategies for stability optimization.[4] I will focus on the strengths and limitations of the different operando scattering techniques, SAXS, XRD, and X-ray total scattering, and how they can be combined, also with X-ray absorption spectroscopy (XAS). This integration offers a complete picture of the catalyst structure at applied potentials, which is fundamtal for establishing structure-property relations.

References

1. J. Schröder, R. K. Pittkowski, I. Martens, R. Chattot, J. Drnec, J. Quinson, J. J. K. Kirkensgaard, M. Arenz, ACS Catal. 2022, 12, 2077–2085.
2. A. Bornet, R. Pittkowski, T. M. Nielsen, E. Berner, A. Maletzko, J. Schröder, J. Quinson, J. Melke, K. M. Ø. Jensen, M. Arenz, ACS Catal. 2023, 7568–7577.
3. J. Schröder, R. K. Pittkowski, J. Du, J. J. K. Kirkensgaard, M. Arenz, J. Electrochem. Soc. 2022, 169, 104504.
4. J. Du, J. Quinson, D. Zhang, B. Wang, G. K. H. Wiberg, R. K. Pittkowski, J. Schröder, S. B. Simonsen, J. J. K. Kirkensgaard, Y. Li, S. Reichenberger, S. Barcikowski, K. M. Ø. Jensen, M. Arenz, JACS Au 2022, 2, 1757–1768.