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O 2 Activation on Ceria Catalysts—The Importance of Substrate Crystallographic Orientation
Author(s) -
Yang Chengwu,
Yu Xiaojuan,
Heißler Stefan,
Weidler Peter G.,
Nefedov Alexei,
Wang Yuemin,
Wöll Christof,
Kropp Thomas,
Paier Joachim,
Sauer Joachim
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201709199
Subject(s) - catalysis , substrate (aquarium) , materials science , oxide , density functional theory , diffusion , redox , characterization (materials science) , metal , crystallography , heterogeneous catalysis , chemical engineering , chemical physics , nanotechnology , chemistry , computational chemistry , metallurgy , thermodynamics , organic chemistry , oceanography , physics , geology , engineering
An atomic‐level understanding of dioxygen activation on metal oxides remains one of the major challenges in heterogeneous catalysis. By performing a thorough surface‐science study of all three low‐index single‐crystal surfaces of ceria, probably the most important redox catalysts, we provide a direct spectroscopic characterization of reactive dioxygen species at defect sites on the reduced ceria (110) and (100) surfaces. Surprisingly, neither of these superoxo and peroxo species was found on ceria (111), the thermodynamically most stable surface of this oxide. Applying density functional theory, we could relate these apparently inconsistent findings to a sub‐surface diffusion of O vacancies on (111) substrates, but not on the less‐closely packed surfaces. These observations resolve a long standing debate concerning the location of O vacancies on ceria surfaces and the activation of O 2 on ceria powders.