Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: Poster Tuesday: Adsorption and Catalysis 1
O 32.5: Poster
Dienstag, 6. September 2022, 11:00–13:00, P3
Adsorption and Diffusion of NH3 on Rutile TiO2(110): An STM Study — •Hanna Bühlmeyer1, Kraen Christoffer Adamsen2, Tao Xu1, Lutz Lammich2, Jörg Libuda1, Stefan Wendt2, and Jeppe Vang Lauritsen2 — 1Interface Research and Catalysis, ECRC, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany — 2Interdisciplinary Nanoscience Center, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
The adsorption of NH3 on TiO2 is an important step for many reactions in environmental catalysis such as the selective catalytic reduction (SCR) of NOX over V2O5/TiO2 and the removal of NH3 from air and water over TiO2. To obtain a detailed understanding of the surface chemistry of NH3 on TiO2, we investigated the adsorption of sub-monolayers of NH3 on clean, hydroxylated, and O-precovered rutile TiO2(110) surfaces by means of scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. We found that on the clean TiO2(110) surface at 120 K, NH3 adsorbs exclusively as monomers. On the hydroxylated TiO2(110) surface at 160 K, we observe 2(NH3) pairs and (NH3)2 dimers in addition to the majority of monomeric NH3. At 270 K, monomeric NH3 and surface hydroxyls diffuse together along the [001] direction. Additionally, NH3 can also diffuse along the surface hydroxyl bridge in the [1-10] direction. On the surface precovered by O adatoms (Oot) at 160 K, we observe the formation of NH2OH and 2(NH2OH) species formed by the interaction of NH3 monomers with Oot and Oot pairs.