A comparative study of mechanisms of the adsorption of CO2 confined within graphene-MoS2 nanosheets: A DFT trend study

Francis M. Enujekwu; Collins I. Ezeh; Michael W. George; Mengxia Xu; Hainam Do; Yue Zhang; Haitao ZHAO; Tao Wu

doi:10.1039/c8na00314a

A comparative study of mechanisms of the adsorption of CO₂ confined within graphene-MoS₂ nanosheets: A DFT trend study

Francis M. Enujekwu, Collins I. Ezeh, Michael W. George, Mengxia Xu, Hainam Do, Yue Zhang, Haitao ZHAO, Tao Wu

Department of Chemical and Environmental Engineering

Research output: Journal Publication › Article › peer-review

21 Citations (Scopus)

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Abstract

The space within the interlayer of 2-dimensional (2D) nanosheets provides new and intriguing confined environments for molecular interactions. However, atomic level understanding of the adsorption mechanism of CO₂ confined within the interlayer of 2D nanosheets is still limited. Herein, we present a comparative study of the adsorption mechanisms of CO₂ confined within graphene-molybdenum disulfide (MoS₂) nanosheets using density functional theory (DFT). A comprehensive analysis of CO₂ adsorption energies (E_AE) at various interlayer spacings of different multilayer structures comprising graphene/graphene (GrapheneB) and MoS₂/MoS₂ (MoS₂B) bilayers as well as graphene/MoS₂ (GMoS₂) and MoS₂/graphene (MoS₂G) hybrids is performed to obtain the most stable adsorption configurations. It was found that 7.5 Å and 8.5 Å interlayer spacings are the most stable conformations for CO₂ adsorption on the bilayer and hybrid structures, respectively. Adsorption energies of the multilayer structures decreased in the following trend: MoS₂B > GrapheneB > MoS₂G > GMoS₂. By incorporating van der Waals (vdW) interactions between the CO₂ molecule and the surfaces, we find that CO₂ binds more strongly on these multilayer structures. Furthermore, there is a slight discrepancy in the binding energies of CO₂ adsorption on the heterostructures (GMoS₂, MoS₂G) due to the modality of the atom arrangement (C-Mo-S-O and Mo-S-O-C) in both structures, indicating that conformational anisotropy determines to a certain degree its CO₂ adsorption energy. Meanwhile, Bader charge analysis shows that the interaction between CO₂ and these surfaces causes charge transfer and redistributions. By contrast, the density of states (DOS) plots show that CO₂ physisorption does not have a substantial effect on the electronic properties of graphene and MoS₂. In summary, the results obtained in this study could serve as useful guidance in the preparation of graphene-MoS₂ nanosheets for the improved adsorption efficiency of CO₂.

Original language	English
Pages (from-to)	1442-1451
Number of pages	10
Journal	Nanoscale Advances
Volume	1
Issue number	4
DOIs	https://doi.org/10.1039/c8na00314a
Publication status	Published - 2019

ASJC Scopus subject areas

Bioengineering
General Chemistry
Atomic and Molecular Physics, and Optics
General Materials Science
General Engineering

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285 A Comparative Study of Mechanisms of the Adsorption of CO2 Confined within Graphene-MoS2 Nanosheets A DFT Trend Study - Published versionFinal published version, 985 KBLicence: CC BY-NC

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title = "A comparative study of mechanisms of the adsorption of CO2 confined within graphene-MoS2 nanosheets: A DFT trend study",

abstract = "The space within the interlayer of 2-dimensional (2D) nanosheets provides new and intriguing confined environments for molecular interactions. However, atomic level understanding of the adsorption mechanism of CO2 confined within the interlayer of 2D nanosheets is still limited. Herein, we present a comparative study of the adsorption mechanisms of CO2 confined within graphene-molybdenum disulfide (MoS2) nanosheets using density functional theory (DFT). A comprehensive analysis of CO2 adsorption energies (EAE) at various interlayer spacings of different multilayer structures comprising graphene/graphene (GrapheneB) and MoS2/MoS2 (MoS2B) bilayers as well as graphene/MoS2 (GMoS2) and MoS2/graphene (MoS2G) hybrids is performed to obtain the most stable adsorption configurations. It was found that 7.5 {\AA} and 8.5 {\AA} interlayer spacings are the most stable conformations for CO2 adsorption on the bilayer and hybrid structures, respectively. Adsorption energies of the multilayer structures decreased in the following trend: MoS2B > GrapheneB > MoS2G > GMoS2. By incorporating van der Waals (vdW) interactions between the CO2 molecule and the surfaces, we find that CO2 binds more strongly on these multilayer structures. Furthermore, there is a slight discrepancy in the binding energies of CO2 adsorption on the heterostructures (GMoS2, MoS2G) due to the modality of the atom arrangement (C-Mo-S-O and Mo-S-O-C) in both structures, indicating that conformational anisotropy determines to a certain degree its CO2 adsorption energy. Meanwhile, Bader charge analysis shows that the interaction between CO2 and these surfaces causes charge transfer and redistributions. By contrast, the density of states (DOS) plots show that CO2 physisorption does not have a substantial effect on the electronic properties of graphene and MoS2. In summary, the results obtained in this study could serve as useful guidance in the preparation of graphene-MoS2 nanosheets for the improved adsorption efficiency of CO2.",

author = "Enujekwu, {Francis M.} and Ezeh, {Collins I.} and George, {Michael W.} and Mengxia Xu and Hainam Do and Yue Zhang and Haitao ZHAO and Tao Wu",

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language = "English",

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T1 - A comparative study of mechanisms of the adsorption of CO2 confined within graphene-MoS2 nanosheets

T2 - A DFT trend study

AU - Enujekwu, Francis M.

AU - Ezeh, Collins I.

AU - George, Michael W.

AU - Xu, Mengxia

AU - Do, Hainam

AU - Zhang, Yue

AU - ZHAO, Haitao

AU - Wu, Tao

PY - 2019

Y1 - 2019

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AB - The space within the interlayer of 2-dimensional (2D) nanosheets provides new and intriguing confined environments for molecular interactions. However, atomic level understanding of the adsorption mechanism of CO2 confined within the interlayer of 2D nanosheets is still limited. Herein, we present a comparative study of the adsorption mechanisms of CO2 confined within graphene-molybdenum disulfide (MoS2) nanosheets using density functional theory (DFT). A comprehensive analysis of CO2 adsorption energies (EAE) at various interlayer spacings of different multilayer structures comprising graphene/graphene (GrapheneB) and MoS2/MoS2 (MoS2B) bilayers as well as graphene/MoS2 (GMoS2) and MoS2/graphene (MoS2G) hybrids is performed to obtain the most stable adsorption configurations. It was found that 7.5 Å and 8.5 Å interlayer spacings are the most stable conformations for CO2 adsorption on the bilayer and hybrid structures, respectively. Adsorption energies of the multilayer structures decreased in the following trend: MoS2B > GrapheneB > MoS2G > GMoS2. By incorporating van der Waals (vdW) interactions between the CO2 molecule and the surfaces, we find that CO2 binds more strongly on these multilayer structures. Furthermore, there is a slight discrepancy in the binding energies of CO2 adsorption on the heterostructures (GMoS2, MoS2G) due to the modality of the atom arrangement (C-Mo-S-O and Mo-S-O-C) in both structures, indicating that conformational anisotropy determines to a certain degree its CO2 adsorption energy. Meanwhile, Bader charge analysis shows that the interaction between CO2 and these surfaces causes charge transfer and redistributions. By contrast, the density of states (DOS) plots show that CO2 physisorption does not have a substantial effect on the electronic properties of graphene and MoS2. In summary, the results obtained in this study could serve as useful guidance in the preparation of graphene-MoS2 nanosheets for the improved adsorption efficiency of CO2.

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A comparative study of mechanisms of the adsorption of CO₂ confined within graphene-MoS₂ nanosheets: A DFT trend study

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