The main objective of my group is a molecular level understanding of catalytic processes on heterogeneous catalyst surfaces. For that purpose, we are utilizing well-defined model systems based on metal single crystals, oxide thin films, and supported metal nanoparticles to study the elemental steps of catalytic reactions. Especially we are interested in the catalytic properties of bimetallic surfaces and nanoparticles.
We are characterizing our model systems in terms of surface structure by Scanning Tunneling Microscopy (STM), Low Energy Ion Scattering (LEIS), and Low Energy Electron Diffraction (LEED). Their chemical composition and electronic properties are obtained by photoelectron spectroscopy (XPS, AES). Available adsorption sites, adsorption/desorption energies, reaction intermediates and possible mechanisms are tested by the adsorption of reactants or probe molecules followed by Infrared – and Temperature Programmed Desorption Spectroscopy (TDS).
To overcome the problems that may arise upon transferring conclusions gained under UHV to a technical catalytic process we are testing the catalytic properties (activity, selectivity) by a combination of reaction analysis (by MS or micro-GC) and in-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRAS) and Sum Frequency Generation (SFG) operating from UHV to atmospheric (∼reaction) conditions. Additionally, we have access to in-situ NAP-XPS and EXAFS at synchrotron facilities.
Most relevant scientific results
- For perovskite base catalyst materials  we could show how doping of the B-site with catalytically highly active elements, and following exsolution during reaction can improve the catalytic reactivity of the surface. For reverse water-gas shift we could demonstrate that the formed nanoparticles are strongly boosting the catalytic reactivity.
- For ZrO2/Pt inverse model catalyst, i.e., ZrO2 particles (islands) grown on a Pt(111) single crystal, we particularly highlighted how the chemical potential of the gas/reaction atmosphere reversibly alters the surface morphology and composition. In comparison to technological systems, only model catalysts can facilitate characterization of the surface (oxidation) state or the role of the metal-support interface at such a distinct level .
- Development of a UHV system with an attached catalytic/spectroscopic high-pressure cell for in situ sum frequency generation (SFG) spectroscopy. SFG is an exceptional tool to study vibrational properties of surface adsorbates under operando conditions, close to those of technical catalysis. Special sample stages allow performing experiments in a temperature range from LN to 1200 K and in a pressure range from UHV to 1.5 bar (in the HP cell). The special design of the HP cell allows measurements at “close to real” catalytic conditions with simultaneous gas analysis (MS) and spectroscopic investigation by SFG .
- With in-situ spectroscopy, combined with electrochemical and catalytic measurements a unique correlation between catalyst structure and catalytic activity and the underlying promotion by electrochemistry was possible . The applied voltage strongly boosts the catalytic reactivity by causing reversible formation of iron nanoparticles on the surface. These nanoparticles are the key for the improved reactivity and an increase of surface conductivity. Furthermore, this is the first example of an electrochemical switchable catalyst (changing reaction completely in 2-3 minutes).
- Ultrathin ZrO2, which only consists of one closed layer of ZrO2, is in comparison to bulk ZrO2 conductive, enabling spectroscopic measurements. Therefore, it is an ideal model system for ZrO2 based catalyst surfaces and solid oxide fuel cells. This research was also the springboard for further investigations on the catalytic reactivity of the ZrO2 surface .
- We gave an example for the importance of in situ investigations to reveal the active state of a catalyst surface. The most active state of a CuZn catalyst (a diluted CuZn alloy decorated with ZnO islands, which are responsible for improved water activation) was characterized under catalytic reaction conditions. Already small alterations of the reaction conditions led to a significant change of the catalyst structure .
- 2020–present: Assistant Prof. at the TU Wien, Institute of Materials Chemistry, Vienna, Austria
- 2013–2019: University Assistant at the TU Wien, Institute of Materials Chemistry, Vienna, Austria
- 2012–2013: Senior Post Doc at the University Innsbruck, Physical Chemistry Department, Innsbruck, Austria
- 2011–2012: Post Doc at the Lawrence Berkeley National Laboratory (LBNL), Chemical Science Division and Advanced Light Source (ALS), Erwin Schrödinger Fellowship of the Austrian Science Fund (FWF), Berkeley, CA, USA
- 2001–2003: Branch manager for OVB Holding AG in Innsbruck
- 2019: Habilitation in Physical Chemistry
- 2011: Ph.D. Chemistry (Dr. rer. nat.), Fritz-Haber-Institute of the Max-Planck-Society, Berlin and University Innsbruck, Austria.
- 2007: M.Sc. Chemistry (Mag. rer. nat.), University Innsbruck, Austria.