2:00 pm – 3:00 pm
Lecture Hall 55.02
We are very happy to welcome within the CRC 1333 Colloquium Series:
Thursday, December 14, 2023, 2:00 – 3:00 pm
University of Turin, Chemistry Department
Topic: “Understanding local structure and reactivity of metal ions in porous catalysts by X-ray spectroscopy”
Elisa Borfecchia obtained her PhD degree in 2013 at the University of Turin. From 2016, she worked at Haldor Topsøe A/S and she was subsequently awarded a Marie Curie Fellowship to join the Catalysis group at Oslo University. From 2019, she has been assistant professor in Physical Chemistry at the University of Turin, where she is currently Associate Professor. She authored > 90 peer-reviewed papers and performed > 60 experiments at synchrotrons. Her research interests are focused on in situ/operando synchrotron-based X-ray absorption and emission spectroscopy, combined with laboratory-based techniques to unravel the local structural and electronic properties of transition metal centres in heterogeneous catalysts. She is also involved in developing innovative experimental setups (e.g., ambient pressure NEXAFS, quasi-simultaneous multi-technique collection) and data analysis methods (e.g., multivariate/statistical analysis, Machine Learning, EXAFS Wavelet transform) for X-ray spectroscopy
X-ray absorption (XAS) and emission (XES) spectroscopies have imposed as powerful techniques to investigate structural and chemical dynamics of metal ions hosted in nanoporous frameworks, such as zeolites and metal-organic frameworks (MOFs), for applications in the field of selective redox catalysis . Analysis of the XANES and EXAFS regions in XAS spectra offers a highly complementary view with respect to diffraction-based methods guaranteeing a unique sensitivity to the local electronic and structural properties of metal centers. These are often disorderly distributed in the crystalline matrix, and occur as dynamic mixtures of different species, responding to the physico-chemical environment while undergoing a rich redox chemistry mediated by host-guest interactions. Continuous instrumental developments at synchrotron sources today enable in situ/operando XAS studies at high time and energy resolution, allowing to monitor such dynamic systems with unprecedented accuracy. In parallel, the combination with XES-based approaches greatly enhances sensitivity to the ligands of the metal centers, allowing discrimination of almost isoelectronic atomic neighbors which is difficulty achieved by XAS. In this contribution, the potential of these methods, empowered by advanced data analysis strategies and synergic integration with multi-technique laboratory characterization and computational modelling, will be exemplified by selected research results.
A first case study will focus on (i) Cu-exchanged zeolites for both deNOx applications via NH3-assisted Selective Catalytic Reduction  as well as for C-H bond activation in light alkanes . A second examples will consider local structural and chemical transformations of redox-active metal ions in Pt- and Cu-functionalized MOFs of the UiO family . Here, the potential of Multivariate Curve Resolution (MCR) of time-resolved XANES datasets, XAS/XES combination and EXAFS Wavelet Transform analysis will be highlighted, to accurately quantify condition/composition-dependent metal speciation and therein establish robust structure-activity relationships, essential to design improved catalysts.
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The CRC cordially invites all who are interested to the lecture.