Starts 4 Jun 2025 14:00
Ends 4 Jun 2025 15:00
Central European Time
CMSP Seminar (Experimental Lecture Series): Applications of X-Ray Absorption and Photoemission spectroscopies in heterogeneous catalysis: the importance of operando conditions
Luigi Stasi Seminar Room (Leonardo Building) and via Zoom
Silvia Mauri
(MAX IV Laboratory, Lund University)
(MAX IV Laboratory, Lund University)
Abstract:
Given the urgency of achieving the forthcoming zero emission targets, the research of green fuels and efficient catalysts able to easily convert them in other valuable compounds is fundamental. XAS and XPS spectroscopies introduced in the previous lecture are fundamental tools in order to investigate the chemistry of catalysts surfaces: the major experimental challenge arises in trying to directly monitor the dynamic chemical mechanisms of catalytic processes during their occurrence, given that usually experiments are performed in UHV ex-situ conditions1. The technological development allowed to design powerful experimental setups able to perform XPS and XAS experiments in real catalytic conditions (operando). This seminar will first give an overview on the different kind of information that operando XPS and XAS spectroscopies can provide, and then will be focused on the application of an innovative setup for operando Soft-XAS developed at APE-HE beamline at Elettra Synchrotron2, which can be exploited to study different catalytic processes. Two case studies will be illustrated: the first one shows the investigation of thermocatalytic partial methane oxidation reaction on the surface of a CuO/CeO2 catalyst3, in which modifications of the electronic structure of Cu active sites have been correlated to the production of oxidized methane products. The second study4 regards the surface reactivity of an A-doped perovskite, a promising anode material for low temperature Solid Oxide Fuel Cells (SOFCs): through operando Soft-XAS and with the help of theoretical spectra simulations (FDMNES code), we directly monitored the surface reduction of Ti atoms during interaction with reducing fuel (H2) at increasing temperature. The multi-technique approach illustrated in the two case studies allowed to extract useful information about the reaction mechanism occurring at the surface of the catalysts, paving the way for a faster design optimization.
1 R. Schlögl. Heterogeneous catalysis. Angewandte Chemie International Edition, 54(11):3465–3520 2015.
2 C. Castán-Guerrero, D. Krizmancic, V. Bonanni, R. Edla, A. Deluisa, F. Salvador, G. Rossi, G. Panaccione, and P. Torelli. A reaction cell for ambient pressure Soft X-Ray absorption spectroscopy. Review of Scientific Instruments, 89(5):054101 2018.
3 S. Mauri, R. Calligaro, C. F. Pauletti, M. F. Camellone, M. Boaro, L. Braglia, S. Fabris, S. Piccinin, P. Torelli, A. Trovarelli, Low-Temperature Methane Activation Reaction Pathways over Mechanochemically-Generated Ce4+/Cu+ Interfacial Sites. Small 20, 2403028 2024.
4 F. Bassato, S. Mauri, L. Braglia, A. Yu. Petrov, E. Dobovičnik, F. Tavani, A. Tofoni, P. Ferrer, D. Grinter, G. Held, P. D’Angelo, and P. Torelli, La0.2Sr0.25Ca0.45TiO3 Surface Reactivity with H2: A Combined Operando NEXAFS and Computational Study, The Journal of Physical Chemistry Letters 15 (33), 8540-8548 2024.
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