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Surface oxygen Vacancies on Reduced Co 3 O 4 (100): Superoxide Formation and Ultra‐Low‐Temperature CO Oxidation
Author(s) -
Liu Yun,
Peng Yuman,
Naschitzki Mathias,
Gewinner Sandy,
Schöllkopf Wieland,
Kuhlenbeck Helmut,
Pentcheva Rossitza,
Roldan Cuenya Beatriz
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202103359
Subject(s) - oxygen , superoxide , catalysis , chemistry , adsorption , photochemistry , redox , vacancy defect , inorganic chemistry , crystallography , organic chemistry , enzyme
The activation of molecular oxygen is a fundamental step in almost all catalytic oxidation reactions. We have studied this topic and the role of surface vacancies for Co 3 O 4 (100) films with a synergistic combination of experimental and theoretical methods. We show that the as‐prepared surface is B‐layer terminated and that mild reduction produces oxygen single and double vacancies in this layer. Oxygen adsorption experiments clearly reveal different superoxide species below room temperature. The superoxide desorbs below ca. 120 K from a vacancy‐free surface and is not active for CO oxidation while superoxide on a surface with oxygen vacancies is stable up to ca. 270 K and can oxidize CO already at the low temperature of 120 K. The vacancies are not refilled by oxygen from the superoxide, which makes them suitable for long‐term operation. Our joint experimental/theoretical effort highlights the relevance of surface vacancies in catalytic oxidation reactions.