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Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity

Atomic dispersion of dopants and control over their defect chemistry are central goals in the development of oxide nanoparticles for functional materials with dedicated electronic, optical or magnetic properties. We produced highly dispersed oxide nanocubes with atomic distribution of cobalt ions in...

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Autores principales: Schwab, Thomas, Niedermaier, Matthias, Zickler, Gregor A., Ončák, Milan, Diwald, Oliver
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756418/
https://www.ncbi.nlm.nih.gov/pubmed/32677720
http://dx.doi.org/10.1002/chem.202002817
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author Schwab, Thomas
Niedermaier, Matthias
Zickler, Gregor A.
Ončák, Milan
Diwald, Oliver
author_facet Schwab, Thomas
Niedermaier, Matthias
Zickler, Gregor A.
Ončák, Milan
Diwald, Oliver
author_sort Schwab, Thomas
collection PubMed
description Atomic dispersion of dopants and control over their defect chemistry are central goals in the development of oxide nanoparticles for functional materials with dedicated electronic, optical or magnetic properties. We produced highly dispersed oxide nanocubes with atomic distribution of cobalt ions in substitutional sites of the MgO host lattice via metal organic chemical vapor synthesis. Vacuum annealing of the nanoparticle powders up to 1173 K has no effect on the shape of the individual particles and only leads to moderate particle coarsening. Such materials processing, however, gives rise to the electronic reduction of particle surfaces, which—upon O(2) admission—stabilize anionic oxygen radicals that are accessible to UV/Vis diffuse reflectance and electron paramagnetic resonance (EPR) spectroscopy. Multi‐reference quantum chemical calculations show that the optical bands observed mainly originate from transitions into (4)A(2g) ((4)F), (4)T(1g) ((4)P) states with a contribution of transitions into (2)T(1g), (2)T(2g) ((2)G) states through spin‐orbit coupling and gain intensity through vibrational motion of the MgO lattice or the asymmetric ion field. Related nanostructures are a promising material system for single atomic site catalysis. At the same time, it represents an extremely valuable model system for the study of interfacial electron transfer processes that are key to nanoparticle chemistry and photochemistry at room temperature, and in heterogeneous catalysis.
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spelling pubmed-77564182020-12-28 Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity Schwab, Thomas Niedermaier, Matthias Zickler, Gregor A. Ončák, Milan Diwald, Oliver Chemistry Full Papers Atomic dispersion of dopants and control over their defect chemistry are central goals in the development of oxide nanoparticles for functional materials with dedicated electronic, optical or magnetic properties. We produced highly dispersed oxide nanocubes with atomic distribution of cobalt ions in substitutional sites of the MgO host lattice via metal organic chemical vapor synthesis. Vacuum annealing of the nanoparticle powders up to 1173 K has no effect on the shape of the individual particles and only leads to moderate particle coarsening. Such materials processing, however, gives rise to the electronic reduction of particle surfaces, which—upon O(2) admission—stabilize anionic oxygen radicals that are accessible to UV/Vis diffuse reflectance and electron paramagnetic resonance (EPR) spectroscopy. Multi‐reference quantum chemical calculations show that the optical bands observed mainly originate from transitions into (4)A(2g) ((4)F), (4)T(1g) ((4)P) states with a contribution of transitions into (2)T(1g), (2)T(2g) ((2)G) states through spin‐orbit coupling and gain intensity through vibrational motion of the MgO lattice or the asymmetric ion field. Related nanostructures are a promising material system for single atomic site catalysis. At the same time, it represents an extremely valuable model system for the study of interfacial electron transfer processes that are key to nanoparticle chemistry and photochemistry at room temperature, and in heterogeneous catalysis. John Wiley and Sons Inc. 2020-10-19 2020-12-04 /pmc/articles/PMC7756418/ /pubmed/32677720 http://dx.doi.org/10.1002/chem.202002817 Text en 2020 The Authors published by Wiley-VCH GmbH This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Full Papers
Schwab, Thomas
Niedermaier, Matthias
Zickler, Gregor A.
Ončák, Milan
Diwald, Oliver
Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title_full Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title_fullStr Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title_full_unstemmed Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title_short Isolated Cobalt Ions Embedded in Magnesium Oxide Nanostructures: Spectroscopic Properties and Redox Activity
title_sort isolated cobalt ions embedded in magnesium oxide nanostructures: spectroscopic properties and redox activity
topic Full Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756418/
https://www.ncbi.nlm.nih.gov/pubmed/32677720
http://dx.doi.org/10.1002/chem.202002817
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