DIFFER Seminar: The influence of doping on the chemical activity of metal clusters

Abstract: Gas phase metal clusters can act as a model system to investigate the active sites of more complex catalyst materials whose reaction mechanisms are poorly understood. However, real-world catalysts often comprise multiple elements with a mixing ratio optimized for better selectivity and reactivity based on screening. We present experiments using a controlled laser generation of bimetallic clusters, of which we study the interaction with small molecules. We do these investigations using a combination of mass-spectrometry and free-electron laser-based IR spectroscopy. The experimental work is complemented by DFT calculations, allowing for structure determination and rationalization of the formed products. In a systematic study of the effect of element substitution, we elucidate the influence of local geometric and electronic structure on the interaction and, thus, of potential catalytic activity. In this contribution, I will present our investigations on how doping of cationic cobalt clusters with foreign elements affects the adsorption modes of CO₂ and H₂/D₂. The experimental results pertain to adsorption reactions on pristine cobalt clusters doped with first-row transition elements (V, Cr, Mn, and Fe). These findings may aid in the design of future catalysts for CO₂ hydrogenation to methanol or other C2 products.

In an outlook, I will discuss possible future research directions using metal ions anchored to fullerene molecules as model system for support single-atom catalysts.