Catalysis

Paramagnetic metal centers or reaction intermediates are involved in many catalytic cycles. Structural and mechanistic insights on these centers can be obtained by a combination of continuous wave (CW) and pulse EPR methods, such as electron spin echo envelope modulation (ESEEM), electron nuclear double resonance (ENDOR) and two-dimensional hyperfine sublevel correlation (HYSCORE). We use and develop methods for both in-situ and operando investigation and ex-situ structural characterization. In-situ and operando EPR allows to observe structural, magnetic and redox transformations under reaction conditions and correlate them with the catalytic activity. Ex-situ pulsed EPR measurements can be used not only for quantifying the distribution of the unpaired electron in the catalysts, but also for guiding synthesis efforts.

We combine EPR with ferromagnetic resonance (FMR) approaches to investigate magnetically ordered systems, with particular focus on the role of defects, such as oxygen vacancies, on the magnetic and catalytic properties of materials. We use density functional theory (DFT) as a complementary tool in our EPR-based structural investigations.

Our group is part of NCCR catalysis research program, in which we collaborate with several groups, including Pérez-Ramírez, Müller and Anastasaki groups (ETH Zurich). We work with single atom catalysts, metal oxides, zeolites, MXenes, metallorganic complexes and reactions such as CO2 to MeOH hydrogenation, NH3 oxidation and depolymerization.
In collaboration with the Copéret group (ETH Zurich) we study surface-bound Ti(III) or Cr(III) species that are related to Ziegler-Natta or Phillips polymerization catalysts.

People: Mikhail Agrachev, Daniel Klose, Katja Raue, Julian Stropp