Epitaxial Cubic Ce2O3 Films via Ce-CeO2 Interfacial Reaction.
Thin films of reduced ceria supported on metals are often applied as substrates in model studies of the chemical reactivity of ceria based catalysts. Of special interest are the properties of oxygen vacancies in ceria. However, thin films of ceria prepared by established methods become increasingly disordered as the concentration of vacancies increases. Here, we propose an alternative method for preparing ordered reduced ceria films based on the physical vapor deposition and interfacial reaction of Ce with CeO2 films. The method yields bulk-truncated layers of cubic c-Ce2O3. Compared to CeO2 these layers contain 25% of perfectly ordered vacancies in the surface and subsurface allowing well-defined measurements of the properties of ceria in the limit of extreme reduction. Experimentally, c-Ce2O3(111) layers are easily identified by a characteristic 4 × 4 surface reconstruction with respect to CeO2(111). In addition, c-Ce2O3 layers represent an experimental realization of a normally unstable polymorph of Ce2O3. During interfacial reaction, c-Ce2O3 nucleates on the interface between CeO2 buffer and Ce overlayer and is further stabilized most likely by the tetragonal distortion of the ceria layers on Cu. The characteristic kinetics of the metal-oxide interfacial reactions may represent a vehicle for making other metastable oxide structures experimentally available.
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Vitalii
V
Stetsovych
‡Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia and S3, Istituto Nanoscienze - CNR, Via G. Campi 213/a, 41125 Modena, Italy.
Federico
F
Pagliuca
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Filip
F
Dvořák
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Tomáš
T
Duchoň
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Mykhailo
M
Vorokhta
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Marie
M
Aulická
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Jan
J
Lachnitt
§Lehrstuhl für Physikalische Chemie II and Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Stefan
S
Schernich
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Iva
I
Matolínová
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Kateřina
K
Veltruská
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Tomáš
T
Skála
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Daniel
D
Mazur
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Josef
J
Mysliveček
§Lehrstuhl für Physikalische Chemie II and Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Jörg
J
Libuda
†Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic.
Vladimír
V
Matolín
ceria; model catalyst; surface oxygen vacancy; surface reduction