Surface chemistry of rare-earth oxide surfaces at ambient conditions: reactions with water and hydrocarbons.
Rare-earth (RE) oxide surfaces are of significant importance for catalysis and were recently reported to possess intrinsic hydrophobicity. The surface chemistry of these oxides in the low temperature regime, however, remains to a large extent unexplored. The reactions occurring at RE surfaces at room temperature (RT) in real air environment, in particular, in presence of polycyclic aromatic hydrocarbons (PAHs), were not addressed until now. Discovering these reactions would shed light onto intermediate steps occurring in automotive exhaust catalysts before reaching the final high operational temperature and full conversion of organics. Here we first address physical properties of the RE oxide, nitride and fluoride surfaces modified by exposure to ambient air and then we report a room temperature reaction between PAH and RE oxide surfaces, exemplified by tetracene (C18H12) on a Gd2O3. Our study evidences a novel effect - oxidation of higher hydrocarbons at significantly lower temperatures (~300 K) than previously reported (>500 K). The evolution of the surface chemical composition of RE compounds in ambient air is investigated and correlated with the surface wetting. Our surprising results reveal the complex behavior of RE surfaces and motivate follow-up studies of reactions between PAH and catalytic surfaces at the single molecule level.
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Elçin
E
Külah
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Laurent
L
Marot
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Roland
R
Steiner
Glas Trösch AG, Industriestrasse 29, 4922 Bützberg, Switzerland.
Andriy
A
Romanyuk
Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen, Switzerland.
Thomas A
TA
Jung
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
Aneliia
A
Wäckerlin
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Ernst
E
Meyer