[Zurück]

L. Haager, F. Kraushofer, M. Eder, A. Rafsanjani-Abbasi, G. Franceschi, M. Riva, P. Sombut, M. Atzmueller, M. Schmid, C. Franchini, U. Diebold, G. Parkinson:
"Comparison of single Rh adatoms on α-Fe₂O₃(1102) and TiO₂(110) stabilized by adsorbed water";
Poster: DPG-Frühjahrstagung (DPG Spring Meeting) of the Surface Science Division, SurfaceScience21, virtual; 04.03.2021.

Despite its high cost, rhodium is a widely applied catalyst primarily used in nanoparticle form for converting toxic gases in automobiles. It is also utilized in organometallic complexes, such as the Wilkinson catalyst, for the hydrogenation of olefins and for converting alkenes to aldehydes through a process known as hydroformylation. So-called single-atom catalysis offers an opportunity to reduce the amount of Rh required for traditional heterogeneous catalysis, and a path to heterogenize homogeneous reactions, with the advantage of easy separation of catalyst and product.

Using STM, nc-AFM and XPS we compare the stability of Rh adatoms on two different model supports: α-Fe2O3(1102) and TiO2(110), both in UHV and 2*10−8 mbar of water. We show that the Rh adatoms on α-Fe2O3(1102) sinter in UHV, but are stabilized by water up to 150 ∘C through coordination to 2-3 OH ligands. In contrast, Rh adatoms on TiO2(110) could not be stabilized above room temperature in either environment.