Structure of endohedral complexes of carbon nanotubes encapsulated with lithium and sodium

Созыкин, С. А.; Бескачко, В. П.

doi:10.1080/00268976.2012.760049

Cited by 6 publications

(9 citation statements)

References 18 publications

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“…During test calculations, we found that with the increase of hydrogen molecules to k = 3–4, these molecules are arranged symmetrically around the Li atom. This arrangement could be the result of the symmetric Coulomb potential of Li + ions (Figure ), since the Li atom, when adsorbed on CNT surface, donates almost all its valence electron to the tube . Thus, for k ≥ 5 we considered symmetrical starting configurations where the H 2 molecules are located compactly near the Li adatom.…”

Section: Results and Discussionmentioning

confidence: 99%

“…To determine the dependence of adsorption energies on CNT translational length, we have considered CNT(5,5) and CNT(7,7) models with N c = 4, 5, 6. At distances for less than four CNT unit cells, we cannot neglect the spurious interaction between Li atom and its image . Hence, the size of chosen models (with Li and H 2 molecules) does not exceed two hundred atoms.…”

Section: Methodsmentioning

confidence: 99%

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Li-Functionalized Carbon Nanotubes for Hydrogen Storage: Importance of Size Effects

Anikina

Banerjee

Бескачко

et al. 2019

ACS Appl. Nano Mater.

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We investigated Li-doped carbon nanotubes (CNTs) as a promising hydrogen storage media. In this computational model, we considered isolated lithium atom adsorbed on a CNT wall as an adsorption site for hydrogen. We focused on the influence of size effects on the structural and energetic characteristics of CNT(n,n)@Li+kH2 complexes where n = 5, 7, 9; k = 1, ..., 6; N c = 4, 5, 6 (N c is translation length of CNT, expressed in terms of a number of CNT unit cells). We proved that modeled CNT length substantially influences internal sorption of Li and hydrogen on the narrow tube (5,5), which subsequently alters the adsorption energies of H2 molecules and causes the deformation of the carbon framework. Moreover, the size effects are not pronounced in the case of external sorption for all considered CNT translation lengths and diameters. We have not observed any noticeable qualitative difference between internal and external hydrogen sorption in the nanotube wider than CNT(5,5). In the case of external adsorption on all considered nanotubes, doping with Li increases hydrogen adsorption energies of up to four H2 molecules by 100 meV in comparison with pure CNTs. And the local density approximation estimations (∼250 meV/H2) of adsorption energy on Li-decorated CNTs exceed the lowest requirement proposed by the U.S. Department of Energy (200 meV/H2). In the case of internal sorption on Li-functionalized tubes, the generalized gradient approximation also gives hydrogen adsorption energies in the desired range of 200–600 meV/H2. However, steric hindrances could prevent sufficient hydrogen uptakes (less than 2 wt % inside CNT(5,5)). We believe that our findings on the size effects are important for estimation of CNT’s hydrogen storage properties.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Li-Functionalized Carbon Nanotubes for Hydrogen Storage: Importance of Size Effects

Anikina

Banerjee

Бескачко

et al. 2019

ACS Appl. Nano Mater.

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“…The minimum CNT diameter D of approximately 7 Å was chosen not to have any steric or diffusion hindrances when placing lithium and molecular hydrogen into carbon nanotube [10]. In case of armchair tubes the value D § 7 Å corresponds with n = 5.…”

Section: Models and Simulation Detailsmentioning

confidence: 99%

“…The perspective element for such use is lithium, because it has high nucleation barrier [8,9]. Recently, Li-doped CNTs have been investigated theoretically and experimentally in search of effective material for Li-ion battery [10,11]. Much less is known about the interaction of these structures with hydrogen.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Studies of Hydrogen Physisorption on Clear and Li-Doped Carbon Nanotubes

Anikina

Бескачко

2017

MMPh

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The hydrogen adsorption on internal and external surfaces of clear and Lidoped carbon nanotubes of different radii are investigated to assess the effects of concavity and doping on hydrogen uptake and binding energy. We make density functional calculations with the exchange-correlation functionals PBE and CA. Modeling of H 2 adsorption on clear carbon tubes shows that only in case of internal sorption on narrow (5,5) nanotube energy of adsorption fall within the desirable range of 300-400 meV per H 2 molecule. But in this case hydrogen uptake is too low and constitutes about 1,6 wt %. Doping with Li atom increases the adsorption energy of hydrogen molecule by 30-100 meV and in case of external sorption this energy enlarges several times. Nevertheless, the optimal range of binding energy can be achieved only in case of hydrogen adsorption inside quite narrow (5,5) and (7,7) Li-doped nanotubes.Keywords: carbon nanotubes; lithium sorption; hydrogen adsorption; firstprinciples calculations; density functional theory. IntroductionHydrogen is considered as one of the most perspective energy carriers as it has a high energy content per mass, it can be generated from clean and green sources and its combustion produces only water as a byproduct [1]. However, for the utilization of H 2 in the national energy systems the difficulties concerning storage and transporting of hydrogen fuels should be overcome.These problems can be solved by using compact and safe hydrogen storages. To create such storages it is necessary to find appropriate hydrogen sorbent. Carbon-based nanomaterials are thoroughly investigated candidates for H 2 storage due to their low density, porosity, high thermal and chemical stability, the simplicity and low cost of production [2]. Carbon nanotubes (CNTs) have not only properties mentioned above but also high mechanical strength, unique electrical and capillary features and therefore they attract a great attention of researches [3]. However, in spite of high surface area clear CNTs can adsorb only up to 1 wt % at room temperature [4] due to the weak bond between H 2 molecules and tube [5].The possible solution of this problem is more active adsorption sites formation, for instance, by doping of carbon nanotubes with metal atoms [6, 7]. The perspective element for such use is lithium, because it has high nucleation barrier [8, 9]. Recently, Li-doped CNTs have been investigated theoretically and experimentally in search of effective material for Li-ion battery [10, 11]. Much less is known about the interaction of these structures with hydrogen. To fill this knowledge gap ab initio modeling based on density functional theory of H 2 physisorption on clear and Li-doped carbon nanotubes was made.

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“…In this context, the physisorption of small aromatic molecules such as polymer wrapping, surfactants, biopolymers and endohedral SWCNT is a good proof to certify this noncovalent attachment and improving the solubility of the SWCNT quite remarkably [9,10]. Indeed, CNTs tend to aggregate due to their strong aromaticity via van der Waals interactions, yielding the formation of strong bundles of CNTs that dissociate with difficulty [11].…”

Section: Introductionmentioning

confidence: 99%

Nanovector formation by functionalization of TRAIL ligand on single-walled carbon nanotube: Experimental and theoretical evidences

Zakaria

Picaud

Duverger

et al. 2015

Chemical Physics Letters

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Structure of endohedral complexes of carbon nanotubes encapsulated with lithium and sodium

Cited by 6 publications

References 18 publications

Li-Functionalized Carbon Nanotubes for Hydrogen Storage: Importance of Size Effects

Li-Functionalized Carbon Nanotubes for Hydrogen Storage: Importance of Size Effects

Ab Initio Studies of Hydrogen Physisorption on Clear and Li-Doped Carbon Nanotubes

Nanovector formation by functionalization of TRAIL ligand on single-walled carbon nanotube: Experimental and theoretical evidences

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