Oxygen Radicals Entrapped between MgO Nanocrystals: Formation, Spectroscopic Fingerprints, and Reactivity toward Water

Thomas Schwab; Eva Muchová; Korbinian Aicher; Thomas Berger; Milan Ončák; Oliver Diwald

doi:10.1021/acs.jpcc.3c06091

Oxygen Radicals Entrapped between MgO Nanocrystals: Formation, Spectroscopic Fingerprints, and Reactivity toward Water

Thomas Schwab, Eva Muchová, Korbinian Aicher, Thomas Berger, Milan Ončák (Corresponding author), Oliver Diwald (Corresponding author)

Chemistry and Physics of Materials

Research output: Contribution to journal › Article › peer-review

Abstract

Compaction of dehydroxylated MgO nanocrystal powders produces adsorbed oxygen radicals with characteristic UV-vis spectroscopic fingerprints. Identical absorption bands arise upon UV excitation in an oxygen atmosphere but in the absence of uniaxial pressure. Photophysical calculations on MgO gas-phase clusters reveal that the observed optical transitions at 4.4 and 3.0 eV are consistent with adsorbed superoxide (O2·-) and ozonide (O3·-) species, respectively. The presence of these oxygen radicals is corroborated by electron paramagnetic resonance spectroscopy. Upon reaction with interfacial water, oxygen radicals convert into diamagnetic products with no absorptions in the UV-vis range. Since superoxide O2·- and ozonide anions O3·- play a key role in a variety of processes in heterogeneous catalysis, sensing, or as transient species in cold sintering, their UV-vis spectroscopic detection will enable in situ monitoring of transient oxygen radicals inside metal oxide powders.

Original language	English
Journal	Journal of Physical Chemistry C
DOIs	https://doi.org/10.1021/acs.jpcc.3c06091
Publication status	Published - Nov 2023

Fields of Science and Technology Classification 2012

104 Chemistry

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10.1021/acs.jpcc.3c06091

Rubbing Powders: Interfacial Radical Formation in Compacted Nanoparticle Ensembles
Diwald, O. (Speaker), Schwab, T. (Speaker), Aicher, K. (Speaker), McKenna, K. (Speaker) & Dunlop, J. (Speaker)
2 Oct 2023
Activity: Talk or presentation › Oral presentation › science to science / art to art

Cite this

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title = "Oxygen Radicals Entrapped between MgO Nanocrystals: Formation, Spectroscopic Fingerprints, and Reactivity toward Water",

abstract = "Compaction of dehydroxylated MgO nanocrystal powders produces adsorbed oxygen radicals with characteristic UV-vis spectroscopic fingerprints. Identical absorption bands arise upon UV excitation in an oxygen atmosphere but in the absence of uniaxial pressure. Photophysical calculations on MgO gas-phase clusters reveal that the observed optical transitions at 4.4 and 3.0 eV are consistent with adsorbed superoxide (O2·-) and ozonide (O3·-) species, respectively. The presence of these oxygen radicals is corroborated by electron paramagnetic resonance spectroscopy. Upon reaction with interfacial water, oxygen radicals convert into diamagnetic products with no absorptions in the UV-vis range. Since superoxide O2·- and ozonide anions O3·- play a key role in a variety of processes in heterogeneous catalysis, sensing, or as transient species in cold sintering, their UV-vis spectroscopic detection will enable in situ monitoring of transient oxygen radicals inside metal oxide powders.",

author = "Thomas Schwab and Eva Muchov{\'a} and Korbinian Aicher and Thomas Berger and Milan On{\v c}{\'a}k and Oliver Diwald",

year = "2023",

month = nov,

doi = "10.1021/acs.jpcc.3c06091",

language = "English",

journal = "Journal of Physical Chemistry C",

issn = "1932-7447",

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T1 - Oxygen Radicals Entrapped between MgO Nanocrystals: Formation, Spectroscopic Fingerprints, and Reactivity toward Water

AU - Schwab, Thomas

AU - Muchová, Eva

AU - Aicher, Korbinian

AU - Berger, Thomas

AU - Ončák, Milan

AU - Diwald, Oliver

PY - 2023/11

Y1 - 2023/11

N2 - Compaction of dehydroxylated MgO nanocrystal powders produces adsorbed oxygen radicals with characteristic UV-vis spectroscopic fingerprints. Identical absorption bands arise upon UV excitation in an oxygen atmosphere but in the absence of uniaxial pressure. Photophysical calculations on MgO gas-phase clusters reveal that the observed optical transitions at 4.4 and 3.0 eV are consistent with adsorbed superoxide (O2·-) and ozonide (O3·-) species, respectively. The presence of these oxygen radicals is corroborated by electron paramagnetic resonance spectroscopy. Upon reaction with interfacial water, oxygen radicals convert into diamagnetic products with no absorptions in the UV-vis range. Since superoxide O2·- and ozonide anions O3·- play a key role in a variety of processes in heterogeneous catalysis, sensing, or as transient species in cold sintering, their UV-vis spectroscopic detection will enable in situ monitoring of transient oxygen radicals inside metal oxide powders.

AB - Compaction of dehydroxylated MgO nanocrystal powders produces adsorbed oxygen radicals with characteristic UV-vis spectroscopic fingerprints. Identical absorption bands arise upon UV excitation in an oxygen atmosphere but in the absence of uniaxial pressure. Photophysical calculations on MgO gas-phase clusters reveal that the observed optical transitions at 4.4 and 3.0 eV are consistent with adsorbed superoxide (O2·-) and ozonide (O3·-) species, respectively. The presence of these oxygen radicals is corroborated by electron paramagnetic resonance spectroscopy. Upon reaction with interfacial water, oxygen radicals convert into diamagnetic products with no absorptions in the UV-vis range. Since superoxide O2·- and ozonide anions O3·- play a key role in a variety of processes in heterogeneous catalysis, sensing, or as transient species in cold sintering, their UV-vis spectroscopic detection will enable in situ monitoring of transient oxygen radicals inside metal oxide powders.

U2 - 10.1021/acs.jpcc.3c06091

DO - 10.1021/acs.jpcc.3c06091

M3 - Article

C2 - 38090143

SN - 1932-7447

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

ER -

Oxygen Radicals Entrapped between MgO Nanocrystals: Formation, Spectroscopic Fingerprints, and Reactivity toward Water

Abstract

Fields of Science and Technology Classification 2012

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Rubbing Powders: Interfacial Radical Formation in Compacted Nanoparticle Ensembles

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