Size‐Dependent Water Structures in Carbon Nanotubes

Ohba, Tomonori

doi:10.1002/ange.201403839

Cited by 25 publications

(43 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results were experimentally verified by our group using NMR spectroscopy [ 26 ]. Structural and vibrational studies [ 39 , 40 ] have also shown that water confined inside a CNT of size 3.0 nm acquires ice-like clusters, showing cooperative motion with high diffusion. In this work, water clusters can diffuse smoothly and fast into these nanopores.…”

Section: Resultsmentioning

confidence: 99%

Effect of Size and Temperature on Water Dynamics inside Carbon Nano-Tubes Studied by Molecular Dynamics Simulation

2021

View full text Add to dashboard Cite

Water transport inside carbon nano-tubes (CNTs) has attracted considerable attention due to its nano-fluidic properties, its importance in nonporous systems, and the wide range of applications in membrane desalination and biological medicine. Recent studies show an enhancement of water diffusion inside nano-channels depending on the size of the nano-confinement. However, the underlying mechanism of this enhancement is not well understood yet. In this study, we performed Molecular Dynamics (MD) simulations to study water flow inside CNT systems. The length of CNTs considered in this study is 20 nm, but their diameters vary from 1 to 10 nm. The simulations are conducted at temperatures ranging from 260 K to 320 K. We observe that water molecules are arranged into coaxial water tubular sheets. The number of these tubular sheets depends on the CNT size. Further analysis reveals that the diffusion of water molecules along the CNT axis deviates from the Arrhenius temperature dependence. The non-Arrhenius relationship results from a fragile liquid-like water component persisting at low temperatures with fragility higher than that of the bulk water.

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of Size and Temperature on Water Dynamics inside Carbon Nano-Tubes Studied by Molecular Dynamics Simulation

2021

View full text Add to dashboard Cite

show abstract

“…(119; 120) Thus under ambient conditions, water within 8 Å CNTs is gas-like, whereas with 11 and 12 Å diameter CNTs the water is ice-like and stack into layers of pentagons or hexagons. (121; 122) For larger diameters still, e.g., 20-30 Å, bound waters form multiple nano-clusters.…”

Section: Negative Curvaturementioning

confidence: 99%

“…(121; 122) For larger diameters still, e.g., 20-30 Å, bound waters form multiple nano-clusters. (120) It is not surprising therefore that there is a non-monotonic relationship between diameter and relative Helmholtz free energy of filling;(121) diameters of 8 and 12 Å represents energy minima. Overall entropy dominates slightly for tube diameters less than 10 Å or greater than 16 Å, and enthalpy dominates for tubes between 11 and 12 Å.…”

Section: Negative Curvaturementioning

confidence: 99%

Molecular Shape and the Hydrophobic Effect

Hillyer

Gibb

2016

Annu. Rev. Phys. Chem.

116

View full text Add to dashboard Cite

This review focuses in papers published since 2000 on the topic of the properties of solutes in water. More specifically, it evaluates the state-of-the-art of our understanding of the complex relationship between the shape of a hydrophobe and the Hydrophobic effect. To highlight this a selection of references covering both empirical and molecular dynamics studies of small (molecular-scale) solutes are presented. These include empirical studies of small molecules, synthetic hosts, crystalline monolayers, and proteins, as well as in silico investigations of entities including idealized hard and soft spheres, small solutes, hydrophobic plates, artificial concavity, molecular hosts, carbon nanotubes and spheres, and proteins. KeywordsWater; non-covalent interactions; supramolecular chemistry; Hydrophobic Effect; hydration ExordiumWater is found in many parts of the universe, but planet Earth truly is a water-world. All four spheres consist to some extent of water: the hydrosphere, biosphere, atmosphere and lithosphere all contain (respectively decreasing) proportions of water. This review pertains to the hydrosphere and biosphere. More specifically, this review concerns the complex relationship between hydrophobic solutes and the solvent of life.(1) For understanding how solute shape and functionality control solvation, and how this solvation folds into measurable spectroscopic and thermodynamic changes, is key to understanding our world.The ubiquity of water is reflected in a massive literature and consequently boundaries must be set for any review. First, although there is a continuum between a hydrophobe and a hard ion, and cases where the Hydrophobic effect (HE) and the Hofmeister effect(2-4) meet,(5; 6) where possible the latter is avoided. Second, this review focuses on the molecular-scale HE(7) and avoids the micro-scale.(8) Third, temperature and pressure can have a considerable effect on the HE,(9) but with only a few exceptions this review concerns ambient conditions. Fourth, bio-membranes are not discussed.(10) Finally, the bulk of this review concerns work performed since 2000.The layout of this review follows the broad types of curvature as defined by mathematics: positive curvature (convex), zero curvature (flat surface) and negative curvature (concave).

show abstract

“…In more confined spaces, however, both of these movement mechanisms are limited; water molecules show less mobility, and could also observe even ice-like behavior in the more restricted end of the interval. [52,53] With less available space to contain water molecules, the number of hopping points is fewer. This is the case for the movement of protons through hydrated graphene interlayer, whose hydrophobicity helps with confining water.…”

Section: Resultsmentioning

confidence: 99%

Hydrous Proton Transfer through Graphene Interlayer: An Extraordinary Mechanism under Magnifier

Zakertabrizi

Hosseini

Korayem

et al. 2021

Adv Materials Technologies

View full text Add to dashboard Cite

However, the novel energy sources extraction and storage technologies, although efficient and green, are complex to fabricate and utilize. [1][2][3][4] Among fuel cells, direct methanol fuel cells (DMFC) show great promise; they use liquid methanol as fuel, which is plentiful and low in cost, and they have a relatively simple and reliable design. [5,6] A key element in the new DMFC fuel cells is the proton exchanging membranes that play a critical role in their performance. These fuel cells are highly susceptible to cathode poisoning, a corrosive phenomenon that happens as undesirable species cross over membranes and reach the cathode, diminishing its potential. As a remedy, selective nanomembranes were introduced which hinder, or completely block the movement of undesirable species. Selective gateways are not a novel phenomenon, as they are present in living organisms and are more suitable for larger ions. Proton-selective channels, on the other hand, can help boost the performance of the new fuel cells deemed to the key to the future of the energy industry and the development of novel fuel cell technologies.The selectivity of a channel is mainly attributed to the function of nanopores geometry, surface chemistry, and environmental conditions that control the ion transport. [7][8][9] These factors were discussed by Razmjou et al. for extracting larger cations in membranes. [10] The key-controlling factors are the dehydration degree of the ions and the nature of the interaction between ions and the inner surface of the channel. Ion movement is facilitated by the existence of water molecules, both as vehicle and as a jumping stage for different ions, making it indispensable for efficient ion conduction. [1] Reducing the channel height, which refers to the smallest dimension of the channel entry, creates an energy barrier that is a direct realization of the spatial obstruction that acts against the hydration shell of the ions. [11,12] Decreasing the channel size, not only creates an energy obstacle against the entering ions, but it also affects the formation of the water molecules inside. The main vehicle for ion transport in this scale is water which is prone to significant phase and behavioral change [13][14][15] under confinement. [16][17][18] This alteration also extends to the ice like formation water under nanoconfinement. [19,20] Under high pressures, water molecules that are trapped inside confinement rearrange their formation and stabilize with unconventional Balancing ionic selectivity against permeability in filters made from graphene remains a challenge today. Interlayer distance, as the most important factor, dominates nearly all aspects of the flow inside the channel, from the formation of water molecules to the hydration shell of the ions. Unraveling the effects of the interlayer distance on the proton diffusion process helps lay a foundation for the cutting-edge proton conduction technology. Here, the reactive molecular dynamics simulations are used to probe the proton flow through a series of hydra...

show abstract

Size‐Dependent Water Structures in Carbon Nanotubes

Cited by 25 publications

References 42 publications

Effect of Size and Temperature on Water Dynamics inside Carbon Nano-Tubes Studied by Molecular Dynamics Simulation

Effect of Size and Temperature on Water Dynamics inside Carbon Nano-Tubes Studied by Molecular Dynamics Simulation

Molecular Shape and the Hydrophobic Effect

Hydrous Proton Transfer through Graphene Interlayer: An Extraordinary Mechanism under Magnifier

Contact Info

Product

Resources

About