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Full reoxidation of CuMn 2 O 4 spinel catalyst triggered by epitaxial Mn 3 O 4 surface nanocrystals
Author(s) -
Trapp Maximilian,
Müller Mathis M.,
Nazarpoor Zahra,
Kleebe HansJoachim
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15032
Subject(s) - spinel , nanocrystalline material , superlattice , epitaxy , materials science , catalysis , nanocrystal , phase (matter) , analytical chemistry (journal) , inorganic chemistry , metallurgy , chemistry , nanotechnology , organic chemistry , layer (electronics) , chromatography , biochemistry , optoelectronics
Transmission electron microscopy was performed on a model system of a novel CuMn 2 O 4 spinel catalyst in order to study the effects of reduction by carbon monoxide and subsequent reoxidation by oxygen both processed at 600°C. A phase transition from CuMn 2 O 4 spinel into separated MnO and Cu‐rich phases, which are CuO or Cu depending on the reduction period, was observed in the reduced samples. Furthermore, a surface coverage of the MnO grains by epitaxially grown, nanocrystalline Mn 3 O 4 was found in all reduced samples. These Mn 3 O 4 nanocrystals are assumed to act as seed crystals in the subsequent reoxidation step completely reversing the phase transitions and reconstituting single‐phase CuMn 2 O 4 spinel. In addition, superlattice reflections due to cation ordering occurred as a typical feature in the as‐prepared spinel. In the reoxidized spinel, the superlattice reflections were absent, hence indicating a disordered cation distribution.