Research interests
My field of expertise is modeling catalytic conversions using density functional theory calculations, aiming to explore reaction mechanisms and adsorption phenomena of possible intermediates at the atomic level. My research has a focus on understanding the crucial transition state to ultimately suggest insight-driven improvements of potential catalysts. This is combined with microkinetic modeling to render computations more comparable to experiment and to get insights on specific pathways that differ only by kinetic means. Most studies were carried out in lockstep with experimental colleagues.
Most relevant scientific results
- Clusters: Nanoparticles may adopt their shape depending on surface coverage. We traced the response of particle shape to the state of the surface and clarified that it follows the reactivity of CO oxidation at Pd nanoparticles. Specifically, the inactive surface state prefers low index surfaces and triggers the particle to produce more of those. The active surface state smoothens out corners and edges to produce the more preferred high index surfaces for that state [1].
The question of selectivity for 1-butene isomerization or hydrogenation over nanoparticles in the size range from 2 to 8 nm was addressed in a combined experimental and theoretical study. DFT calculations with extensive microkinetic modeling rationalized the selectivity towards isomerization to depend on the occurrence of corrugated surfaces, while flat terraces blocked this pathway. Therefore, small particles were more active in isomerization [2].
When nanoparticles grow, their properties slowly change to adopt those of single crystal surfaces. Experimentally suddenly large negative adsorption strengths have been determined for relatively small particles, so the question arose, if there is another trend. We determined such a minimum value for CO adsorption at particles with ~30 Pd atoms [3]. - Metal surfaces: The conversion of biomass to useful chemicals will be a field of growing importance, especially the access to aromatics. Ru(0001) surfaces are particularly active in the deoxygenation of guaiacol, a surrogate of wood related biomass. We modelled the mechanism to understand the quick deactivation of this patented catalyst to improve upon it [4].
- Metal complexes: Making adipic acid from glucose is another patented example for using biomass as feedstock. In this catalysis the crucial step is carried out using a Pd-complex with a custom designed ligand. Understanding this ligand and helping to determine helpful motives was the main task for this modelling study to enable targeted improvements [5].
- Metal oxide bulk/surfaces: In reducible oxides, the metal atoms may assume more than one role depending on their actual oxidation state. This renders their modelling especially complex. A V2O5 anode material was modelled for Li ion diffusion. Once understanding the role of the oxidation state, it became clear that the movement of a V4+ center is actually crucial to the diffusion of its associated Li+ ion. Such materials are very active in the selective oxidation via a Mars-van-Krevelen mechanism [6]. Co3O4 is an example of such a material, exhibiting remarkable catalytic activity in CO activation. However, it also suffers from rapid deactivation. In an experimental study combined with modeling, we demonstrated that the active site may alternatively bind CO instead of O2, thereby blocking its catalytic activity [7].
Career
- 2020-present: University Assistant, Institute of Materials Chemistry, TU Wien, Austria.
- 2015-2020: Senior Scientist II, Institute of High Performance Computing (IHPC), A*STAR, Singapore.
- 2012-2015: Senior Scientist I, IHPC, A*STAR, Singapore.
- 2007-2012: Research Assistant, Department Chemie, TU München, Germany.
Education
- 2007: Ph.D. Chemistry (Dr. rer. nat.), Technical University Munich, Germany.
- 2002: Diploma Chemistry (Mag. rer. nat.), Technical University Munich, Germany.