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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...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American
Chemical Society
2018
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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. |
format | Online Article Text |
id | pubmed-6135594 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | American
Chemical Society |
record_format | MEDLINE/PubMed |
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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