Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation

The origin of selectivity and activity of the CO2 hydrogenation reaction on single-atom catalysts composed of three adjacent 3d transition metals (Fe, Co, and Ni) supported on N-doped graphene quantum dots were systematically investigated and compared using density functional theory (DFT) calculatio...

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Main Authors: Armin Mahmoudi, Siyavash Kazemi Movahed, Hossein Farrokhpour
Format: Article
Language:English
Published: Elsevier 2024-12-01
Series:Carbon Trends
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Online Access:http://www.sciencedirect.com/science/article/pii/S266705692400110X
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author Armin Mahmoudi
Siyavash Kazemi Movahed
Hossein Farrokhpour
author_facet Armin Mahmoudi
Siyavash Kazemi Movahed
Hossein Farrokhpour
author_sort Armin Mahmoudi
collection DOAJ
description The origin of selectivity and activity of the CO2 hydrogenation reaction on single-atom catalysts composed of three adjacent 3d transition metals (Fe, Co, and Ni) supported on N-doped graphene quantum dots were systematically investigated and compared using density functional theory (DFT) calculations, natural bond orbital (NBO), and quantum theory of atoms in molecules (QTAIM) analysis. This study reveals that π-backbonding between the metal and CO2* does not occur and [CO2]δ+ species drive the reaction. The CO2* reacts with H2 via the Eley-Rideal (ER) mechanism by using the synergistic effects of the N site. The higher the partial positive charge on the C atom, the lower the Ea of the reaction. Subsequently, a tautomerization reaction, which is facilitated by hydrogen bonding, occurs and hydrogen is transferred to HCOO* resulting in the formation of CHOOH*. This study shows the selective formation of formic acid from CO2 is accessible on these SACs and Fe-SAC is the best one between these three catalysts. Although CO2 is more inert than formic acid the H2 molecule reacts with the adsorbed formic acid more difficult than the adsorbed CO2. It is because the hydrogenation of formic acid causes C-H bond formation resulting in failure of the coordinated O atom's octet and the unstable H2COOH* is formed. This step is the rate-determining step of HOCH2OH formation from CO2, with Ea of 1.94, 2.03, and 2.23 eV for Fe, Co, and Ni, respectively. Finally, the system undergoes another tautomerization reaction resulting in the formation of HOCH2OH (formaldehyde monohydrate).
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spelling doaj-art-a7b27398cd9640e7a5a1b78b1718fa382024-12-15T06:17:39ZengElsevierCarbon Trends2667-05692024-12-0117100430Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenationArmin Mahmoudi0Siyavash Kazemi Movahed1Hossein Farrokhpour2Department of Chemistry, Isfahan University of Technology, Isfahan 8415683111, IranCorrespondence authors at: Department of Chemistry, Isfahan University of Technology, Isfahan 8415683111, Iran.; Department of Chemistry, Isfahan University of Technology, Isfahan 8415683111, IranCorrespondence authors at: Department of Chemistry, Isfahan University of Technology, Isfahan 8415683111, Iran.; Department of Chemistry, Isfahan University of Technology, Isfahan 8415683111, IranThe origin of selectivity and activity of the CO2 hydrogenation reaction on single-atom catalysts composed of three adjacent 3d transition metals (Fe, Co, and Ni) supported on N-doped graphene quantum dots were systematically investigated and compared using density functional theory (DFT) calculations, natural bond orbital (NBO), and quantum theory of atoms in molecules (QTAIM) analysis. This study reveals that π-backbonding between the metal and CO2* does not occur and [CO2]δ+ species drive the reaction. The CO2* reacts with H2 via the Eley-Rideal (ER) mechanism by using the synergistic effects of the N site. The higher the partial positive charge on the C atom, the lower the Ea of the reaction. Subsequently, a tautomerization reaction, which is facilitated by hydrogen bonding, occurs and hydrogen is transferred to HCOO* resulting in the formation of CHOOH*. This study shows the selective formation of formic acid from CO2 is accessible on these SACs and Fe-SAC is the best one between these three catalysts. Although CO2 is more inert than formic acid the H2 molecule reacts with the adsorbed formic acid more difficult than the adsorbed CO2. It is because the hydrogenation of formic acid causes C-H bond formation resulting in failure of the coordinated O atom's octet and the unstable H2COOH* is formed. This step is the rate-determining step of HOCH2OH formation from CO2, with Ea of 1.94, 2.03, and 2.23 eV for Fe, Co, and Ni, respectively. Finally, the system undergoes another tautomerization reaction resulting in the formation of HOCH2OH (formaldehyde monohydrate).http://www.sciencedirect.com/science/article/pii/S266705692400110XCO2 hydrogenationNitrogen dopingSingle-atom catalystDensity functional theory: Graphene quantum dotSynergistic activation
spellingShingle Armin Mahmoudi
Siyavash Kazemi Movahed
Hossein Farrokhpour
Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
Carbon Trends
CO2 hydrogenation
Nitrogen doping
Single-atom catalyst
Density functional theory: Graphene quantum dot
Synergistic activation
title Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
title_full Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
title_fullStr Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
title_full_unstemmed Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
title_short Mechanistic insight into the catalytic activities of metallic sites on nitrogen-doped graphene quantum dots for CO2 hydrogenation
title_sort mechanistic insight into the catalytic activities of metallic sites on nitrogen doped graphene quantum dots for co2 hydrogenation
topic CO2 hydrogenation
Nitrogen doping
Single-atom catalyst
Density functional theory: Graphene quantum dot
Synergistic activation
url http://www.sciencedirect.com/science/article/pii/S266705692400110X
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AT siyavashkazemimovahed mechanisticinsightintothecatalyticactivitiesofmetallicsitesonnitrogendopedgraphenequantumdotsforco2hydrogenation
AT hosseinfarrokhpour mechanisticinsightintothecatalyticactivitiesofmetallicsitesonnitrogendopedgraphenequantumdotsforco2hydrogenation