Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation

Cobalt and iron MCM-41 catalysts were synthesized through an in-situ incorporation process starting from commercial iron and cobalt nitrates. The incorporation was confirmed by diffuse reflectance UV spectroscopy (DRS-UV) inspecting the cobalt and iron silicate-like photon absorption features an...

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Autor principal:	Frank Ramírez-Rodríguez, Betty López
Formato:	article
Lenguaje:	EN ES
Publicado:	Pontificia Universidad Javeriana 2020
Materias:	dft; raman; swcnt; uv-vis. Science (General) Q1-390
Acceso en línea:	https://doaj.org/article/1082f6057a5b466faaa06eaf48485e71
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spelling	oai:doaj.org-article:1082f6057a5b466faaa06eaf48485e712021-11-16T20:14:05ZSingle wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation10.11144/Javeriana.SC25-2.swcn0122-74832027-1352https://doaj.org/article/1082f6057a5b466faaa06eaf48485e712020-07-01T00:00:00Zhttps://revistas.javeriana.edu.co/index.php/scientarium/article/view/25896https://doaj.org/toc/0122-7483https://doaj.org/toc/2027-1352Cobalt and iron MCM-41 catalysts were synthesized through an in-situ incorporation process starting from commercial iron and cobalt nitrates. The incorporation was confirmed by diffuse reflectance UV spectroscopy (DRS-UV) inspecting the cobalt and iron silicate-like photon absorption features and comparing with pure MCM-41-Co and MCM-41-Fe catalysts. Additionally it was found that the incorporation of cobalt and iron does not compromise the mesoporous structure of MCM-41 as confirmed by N2 adsorption isotherms. All catalysts showed high surface areas (∼1100 m2 g −1 ). Catalysts performance was conducted in a simple methane chemical vapor deposition (CVD) set up at 800 °C to produce single wall carbon nanotubes (SWCNT) under a constant flow of methane for 30 min. CVD products were characterized by thermogravimetric analysis (TGA) and Raman spectroscopy, finding that the iron content in the catalysts favors the selectivity and yield of graphitic-like structures, and confirming the presence of SWCNT by the appearance of a characteristic radial breathing mode (RBM) signals. These results were supported by Density Functional Theory (DFT) simulations of the methane dissociation (CH4 +TM → H3C –TMH) over Con (n = 1–5) and ComFe (m = 1–4), finding a different activation energy trend where ComFe (m = 1–4) clusters have the lower activation energy. The DFT study also revealed a charge difference (δC − δTM) higher in the case of dissociation over ComFe (m = 1–4) which may lead to an electrostatic stabilization of the transition metal, diminishing the activation energy of those clusters and leading to a faster carbon uptake. Frank Ramírez-Rodríguez, Betty LópezPontificia Universidad Javerianaarticledft; raman; swcnt; uv-vis.Science (General)Q1-390ENESUniversitas Scientiarum, Vol 25, Iss 2, Pp 227-246 (2020)
institution	DOAJ
collection	DOAJ
language	EN ES
topic	dft; raman; swcnt; uv-vis. Science (General) Q1-390
spellingShingle	dft; raman; swcnt; uv-vis. Science (General) Q1-390 Frank Ramírez-Rodríguez, Betty López Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
description	Cobalt and iron MCM-41 catalysts were synthesized through an in-situ incorporation process starting from commercial iron and cobalt nitrates. The incorporation was confirmed by diffuse reflectance UV spectroscopy (DRS-UV) inspecting the cobalt and iron silicate-like photon absorption features and comparing with pure MCM-41-Co and MCM-41-Fe catalysts. Additionally it was found that the incorporation of cobalt and iron does not compromise the mesoporous structure of MCM-41 as confirmed by N2 adsorption isotherms. All catalysts showed high surface areas (∼1100 m2 g −1 ). Catalysts performance was conducted in a simple methane chemical vapor deposition (CVD) set up at 800 °C to produce single wall carbon nanotubes (SWCNT) under a constant flow of methane for 30 min. CVD products were characterized by thermogravimetric analysis (TGA) and Raman spectroscopy, finding that the iron content in the catalysts favors the selectivity and yield of graphitic-like structures, and confirming the presence of SWCNT by the appearance of a characteristic radial breathing mode (RBM) signals. These results were supported by Density Functional Theory (DFT) simulations of the methane dissociation (CH4 +TM → H3C –TMH) over Con (n = 1–5) and ComFe (m = 1–4), finding a different activation energy trend where ComFe (m = 1–4) clusters have the lower activation energy. The DFT study also revealed a charge difference (δC − δTM) higher in the case of dissociation over ComFe (m = 1–4) which may lead to an electrostatic stabilization of the transition metal, diminishing the activation energy of those clusters and leading to a faster carbon uptake.
format	article
author	Frank Ramírez-Rodríguez, Betty López
author_facet	Frank Ramírez-Rodríguez, Betty López
author_sort	Frank Ramírez-Rodríguez, Betty López
title	Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
title_short	Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
title_full	Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
title_fullStr	Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
title_full_unstemmed	Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation
title_sort	single wall carbon nanotubes growth over cobalt-iron mesoporous mcm-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and dft evaluation
publisher	Pontificia Universidad Javeriana
publishDate	2020
url	https://doaj.org/article/1082f6057a5b466faaa06eaf48485e71
work_keys_str_mv	AT frankramirezrodriguezbettylopez singlewallcarbonnanotubesgrowthovercobaltironmesoporousmcm41bimetalliccatalystundermethanechemicalvapordepositionanexperimentalanddftevaluation
_version_	1718426031204859904

Single wall carbon nanotubes growth over cobalt-iron mesoporous MCM-41 bimetallic catalyst under methane chemical vapor deposition, an experimental and DFT evaluation

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