Epitaxial Cubic Ce2O3 Films via Ce鈥揅eO2 Interfacial Reaction

详细信息    查看全文

• 作者：Vitalii Stetsovych ; Federico Pagliuca ; Filip Dvo艡谩k ; Tom谩拧 Ducho艌 ; Mykhailo Vorokhta ; Marie Aulick谩 ; Jan Lachnitt ; Stefan Schernich ; Iva Matol铆nov谩 ; Kate艡ina Veltrusk谩 ; Tom谩拧 Sk谩la ; Daniel Mazur ; Josef Myslive膷ek ; J枚rg Libuda ; Vladim铆r Matol铆n
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2013
• 出版时间：March 21, 2013
• 年：2013
• 卷：4
• 期：6
• 页码：866-871
• 全文大小：414K
• 年卷期：v.4,no.6(March 21, 2013)
• ISSN：1948-7185

文摘

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 CeOb>2b> films. The method yields bulk-truncated layers of cubic c-Ceb>2b>Ob>3b>. Compared to CeOb>2b> 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-Ceb>2b>Ob>3b>(111) layers are easily identified by a characteristic 4 脳 4 surface reconstruction with respect to CeOb>2b>(111). In addition, c-Ceb>2b>Ob>3b> layers represent an experimental realization of a normally unstable polymorph of Ceb>2b>Ob>3b>. During interfacial reaction, c-Ceb>2b>Ob>3b> nucleates on the interface between CeOb>2b> 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鈥搊xide interfacial reactions may represent a vehicle for making other metastable oxide structures experimentally available.<br>

Keywords:

ceria; model catalyst; surface oxygen vacancy; surface reduction