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Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD

[Image: see text] Cobalt oxide Co(3)O(4) has recently emerged as promising, noble metal-free catalyst for oxidation reactions but a better understanding of the active catalyst under working conditions is required for further development and potential commercialization. An operando approach has been...

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Autores principales: Lukashuk, Liliana, Yigit, Nevzat, Rameshan, Raffael, Kolar, Elisabeth, Teschner, Detre, Hävecker, Michael, Knop-Gericke, Axel, Schlögl, Robert, Föttinger, Karin, Rupprechter, Günther
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2018
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135594/
https://www.ncbi.nlm.nih.gov/pubmed/30221030
http://dx.doi.org/10.1021/acscatal.8b01237
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author Lukashuk, Liliana
Yigit, Nevzat
Rameshan, Raffael
Kolar, Elisabeth
Teschner, Detre
Hävecker, Michael
Knop-Gericke, Axel
Schlögl, Robert
Föttinger, Karin
Rupprechter, Günther
author_facet Lukashuk, Liliana
Yigit, Nevzat
Rameshan, Raffael
Kolar, Elisabeth
Teschner, Detre
Hävecker, Michael
Knop-Gericke, Axel
Schlögl, Robert
Föttinger, Karin
Rupprechter, Günther
author_sort Lukashuk, Liliana
collection PubMed
description [Image: see text] Cobalt oxide Co(3)O(4) has recently emerged as promising, noble metal-free catalyst for oxidation reactions but a better understanding of the active catalyst under working conditions is required for further development and potential commercialization. An operando approach has been applied, combining near ambient (atmospheric) pressure X-ray photoelectron spectroscopy (NAP-XPS), Fourier transform infrared spectroscopy (FTIR), or X-ray diffraction (XRD) with simultaneous catalytic tests of CO oxidation on Co(3)O(4), enabling one to monitor surface and bulk states under various reaction conditions (steady-state and dynamic conditions switching between CO and O(2)). On the basis of the surface-specific chemical information a complex network of different reaction pathways unfolded: Mars-van-Krevelen (MvK), CO dissociation followed by carbon oxidation, and formation of carbonates. A possible Langmuir–Hinshelwood (LH) pathway cannot be excluded because of the good activity when no oxygen vacancies were detected. The combined NAP-XPS/FTIR results are in line with a MvK mechanism above 100 °C, involving the Co(3+)/Co(2+) redox couple and oxygen vacancy formation. Under steady state, the Co(3)O(4) surface appeared oxidized and the amount of reduced Co(2+) species at/near the surface remained low up to 200 °C. Only in pure CO, about 15% of surface reduction were detected, suggesting that the active sites are a minority species. The operando spectroscopic studies also revealed additional reaction pathways: CO dissociation followed by carbon reoxidation and carbonate formation and its decomposition. However, due to their thermal stability in various atmospheres, the carbonates are rather spectators and also CO dissociation seems a minor route. This study thus highlights the benefits of combining operando surface sensitive techniques to gain insight into catalytically active surfaces.
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spelling pubmed-61355942018-09-13 Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD Lukashuk, Liliana Yigit, Nevzat Rameshan, Raffael Kolar, Elisabeth Teschner, Detre Hävecker, Michael Knop-Gericke, Axel Schlögl, Robert Föttinger, Karin Rupprechter, Günther ACS Catal [Image: see text] Cobalt oxide Co(3)O(4) has recently emerged as promising, noble metal-free catalyst for oxidation reactions but a better understanding of the active catalyst under working conditions is required for further development and potential commercialization. An operando approach has been applied, combining near ambient (atmospheric) pressure X-ray photoelectron spectroscopy (NAP-XPS), Fourier transform infrared spectroscopy (FTIR), or X-ray diffraction (XRD) with simultaneous catalytic tests of CO oxidation on Co(3)O(4), enabling one to monitor surface and bulk states under various reaction conditions (steady-state and dynamic conditions switching between CO and O(2)). On the basis of the surface-specific chemical information a complex network of different reaction pathways unfolded: Mars-van-Krevelen (MvK), CO dissociation followed by carbon oxidation, and formation of carbonates. A possible Langmuir–Hinshelwood (LH) pathway cannot be excluded because of the good activity when no oxygen vacancies were detected. The combined NAP-XPS/FTIR results are in line with a MvK mechanism above 100 °C, involving the Co(3+)/Co(2+) redox couple and oxygen vacancy formation. Under steady state, the Co(3)O(4) surface appeared oxidized and the amount of reduced Co(2+) species at/near the surface remained low up to 200 °C. Only in pure CO, about 15% of surface reduction were detected, suggesting that the active sites are a minority species. The operando spectroscopic studies also revealed additional reaction pathways: CO dissociation followed by carbon reoxidation and carbonate formation and its decomposition. However, due to their thermal stability in various atmospheres, the carbonates are rather spectators and also CO dissociation seems a minor route. This study thus highlights the benefits of combining operando surface sensitive techniques to gain insight into catalytically active surfaces. American Chemical Society 2018-08-07 2018-09-07 /pmc/articles/PMC6135594/ /pubmed/30221030 http://dx.doi.org/10.1021/acscatal.8b01237 Text en Copyright © 2018 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Lukashuk, Liliana
Yigit, Nevzat
Rameshan, Raffael
Kolar, Elisabeth
Teschner, Detre
Hävecker, Michael
Knop-Gericke, Axel
Schlögl, Robert
Föttinger, Karin
Rupprechter, Günther
Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title_full Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title_fullStr Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title_full_unstemmed Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title_short Operando Insights into CO Oxidation on Cobalt Oxide Catalysts by NAP-XPS, FTIR, and XRD
title_sort operando insights into co oxidation on cobalt oxide catalysts by nap-xps, ftir, and xrd
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135594/
https://www.ncbi.nlm.nih.gov/pubmed/30221030
http://dx.doi.org/10.1021/acscatal.8b01237
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