Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 64: Oxides and Interfaces: Adsorption II

O 64.5: Talk

Wednesday, March 9, 2016, 16:00–16:15, H6

Single Rh adatoms at the Fe₃O₄(001) surface and their interaction with gas molecules — •Roland Bliem, Adam Zavodny, Michael Schmid, Peter Blaha, Ulrike Diebold, and Gareth Steven Parkinson — TU Wien, Vienna, Austria

Single-atom catalysis is a hot topic in catalysis research, aiming for high activity at optimum efficiency in the usage of precious metals. Understanding the reaction mechanisms in this emerging field requires atomic-scale information about the interaction of single metal adatoms with gas molecules. The Fe₃O₄(001) surface is an ideal model system to study adatom-gas interactions as well as a promising support material for single-atom catalysis, because its (√2× √2)R45^∘ reconstruction [1] provides strong adsorption sites stabilizing single metal adatoms up to temperatures as high as 700K [2,3].

Here, we present a room-temperature study of Rh adatoms and their interaction with O₂, NO, CO, and H₂O using scanning tunnelling microscopy (STM) and density functional theory (DFT+U). Rh adatoms interact with each gas in a different way: O₂ adsorbs strongly, causing adatom mobility and sintering. NO adsorption also leads to mobility but hardly any clustering is observed. In contrast, CO adsorption does not induce mobility but poisons the activity for O₂ adsorption. Furthermore, Rh adatoms facilitate water splitting. DFT calculations yield bond strengths of O₂ and CO and metal-adsorbate bond lengths.

[1] Bliem et al. Science 346, 1215-1218 (2014).

[2] Novotny et al. Phys. Rev. Lett. 108, 216103 (2012).

[3] Bliem et al. ACS Nano 8, 7531-7537 (2014).