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 CO 2 confined within the interlayer of 2D nanosheets is still limited. Herein, we present a comparative study of the adsorption mechanisms of CO 2 confined within graphene-molybdenum disulfide (MoS 2 ) nanosheets using density functional theory (DFT). A comprehensive analysis of CO 2 adsorption energies (E AE ) at various interlayer spacings of different multilayer structures comprising graphene/graphene (GrapheneB) and MoS 2 /MoS 2 (MoS 2 B) bilayers as well as graphene/MoS 2 (GMoS 2 ) and MoS 2 /graphene (MoS 2 G) hybrids is performed to obtain the most stable adsorption configurations. It was found that 7.5Å and 8.5Å interlayer spacings are the most stable conformations for CO 2 adsorption on the bilayer and hybrid structures, respectively. Adsorption energies of the multilayer structures decreased in the following trend: MoS 2 B > GrapheneB > MoS 2 G > GMoS 2 . By incorporating van der Waals (vdW) interactions between the CO 2 molecule and the surfaces, we find that CO 2 binds more strongly on these multilayer structures. Furthermore, there is a slight discrepancy in the binding energies of CO 2 adsorption on the heterostructures (GMoS 2 , MoS 2 G) 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 CO 2 adsorption energy. Meanwhile, Bader charge analysis shows that the interaction between CO 2 and these surfaces causes charge transfer and redistributions.By contrast, the density of states (DOS) plots show that CO 2 physisorption does not have a substantial effect on the electronic properties of graphene and MoS 2 . In summary, the results obtained in this study could serve as useful guidance in the preparation of graphene-MoS 2 nanosheets for the improved adsorption efficiency of CO 2 .

Theoretical Insights into CO2 Adsorption by MoS2 Nanomaterials

“…The reported results show the suitability of MoS 2 -based nanomaterials for CO 2 -related operations, which would allow to consider this material alone or combined with other 2D materials, as recently proposed by Enujekwu et al 98 In particular, the suitable diffusion of CO 2 through MoS 2 nanopores shows promising ability of nanoporous MoS 2 for CO 2 capturing purposes as previously reported for water desalination purposes. 79 As a suggestion for future studies, finding suitable pore size and geometries as a function of flue gas composition are properties that could allow fine tuning of MoS 2 nanomaterials for gas treatment.…”

Highly Selective CO2 Capture and Its Direct Photochemical Conversion on Ordered 2D/1D Heterojunctions

“…Charge transfer from rGO to CNNA changes the electronic environment and causes charge redistribution, obviously improving polarity and polarizability and thereby the adsorption strength. 61,62 As shown in Figure 3B, the CO 2 uptake increases sharply as the pressure increases, while the N 2 adsorption capacity only slightly increases in the pressure range. The calulated CO 2 /N 2 selectivity is 44, which is even comparable to those values of performance separation products.…”

Efficient CO2 Capture and Activation on Novel Two-Dimensional Transition Metal Borides

“…to the environment from industries, gas adsorbent materials (GAMs) have gained considerable attention from many researchers across the globe. , Among these environmental pollutants, the concentration of CO 2 in the atmosphere has increased tremendously (313 ppm (1960) to 415 ppm (2021)) . The increase in CO 2 concentration can be linked to the massive dependence on fossil fuels in the past century . Therefore, mitigation and capture of greenhouse gases (GHGs) are some of the most challenging issues in environmental protection .…”

“…To deal with global warming, cost-effective and efficient capture of CO 2 and other GHGs through industrially proven and simple processes like adsorption is essential. Many GAMs have been developed experimentally and computationally in the past; nanostructured materials are at the cutting edge of potentially revolutionary advancements in rapidly growing technological fields such as energy storage and harvesting, molecular sensing, environmental and sustainability engineering, etc. ,− Nanostructured materials have attracted attention because of their unprecedented properties for various technological applications arising due to the quantum confinements and tunability. , Their high surface area-to-volume ratio, good transport properties, and tunable reactivity make them attractive for CO 2 conversion to valuable chemical products or CCS applications. , …”