Water In Nanotubes Research Articles

First-Principles Study of Water Nanotubes Captured Inside Carbon/Boron Nitride Nanotubes.

Water confined to nanopores such as carbon nanotubes (CNTs) exhibits different states, enabling the study of solidlike water nanotubes (WNTs) and the potential application of their properties due to confined effects. Herein, we report the interfacial interaction and particular stabilized boundaries of confined WNTs within CNTs and boron nitride nanotubes (BNNTs) using first-principles calculations. We demonstrate that the intermolecular potential of nanotube walls exerts diameter-dependent additive or subtractive van der Waals (vdW) pressure on the WNTs, altering the phase boundaries. Our results reveal that the most stable WNT@CNT is associated with a CNT diameter of 10.5 Å. By correlating the stability of WNTs with interfacial properties such as the vdW pressure and vibrational phonon modes of confined WNTs, we decode and compare various synergies in water interaction and stabilized states within the CNTs and BNNTs, including interfacial properties of WNT@BNNTs that are more significant than those of WNT@CNTs. Our results suggest that the transition of a water tube to an ice tube is strongly dependent on the diameter of the confining CNT or BNNT, providing new insights on leveraging the interfacial interaction mechanism of confined WNTs and their potential application for fabricating nanochannels and nanocapacitors.

Electrochemical Deposition of Composites Using Deoxycholic Acid Dispersant

A biomimetic method has been used for the electrodeposition of carbon nanotubes (NTs) and composite films using a commercial bile acid. Thin films of deoxycholic acid (DCH) were prepared potentiodynamically and galvanostatically from deoxycholic acid sodium salt (DCNa) solutions. The anodic deposition yield has been investigated at different DCNa concentrations. The electrodeposition mechanism involved electromigration of anionic DC− species, local pH reduction at the anode, and precipitation of DCH. It was found that DCNa allowed excellent dispersion of NTs in water. The use of DCNa as a multifunctional agent for NTs dispersion, charging, and binding allowed electrodeposition of NTs and composite MnO2–NTs films. The MnO2–NTs composites were used for charge storage applications in supercapacitors. The MnO2–NTs electrodes showed good capacitive behavior. DCNa is a promising charging dispersant for NTs dispersion and manufacturing of other composites by electrochemical methods.

Eigen-like hydrated protons traveling with a local distortion through the water nanotube in new molecular porous crystals {[MIII(H2bim)3](TMA)·20H2O}n (M = Co, Rh, Ru)

In molecular porous crystals {[M(III)(H(2)bim)(3)](TMA)·20H(2)O}(n) (M = Co, Rh, Ru), the structural property of confined water network and the dynamics of mobile hydrated protons have been examined by the measurement of infrared spectrum and microwave conductivity. The water network undergoes first order phase transition from the ice nanotube (INT) to the water nanotube (WNT) around 200 K, while the infrared spectral features for these states are almost equivalent. Consequently, the water molecules in WNT dynamically fluctuate in the vicinity of the regulated position in INT with maintaining the O-O distance. The additional band observed around 2200 cm(-1) reveals the emergence of an Eigen-like protonic hydrate, around which the O-O distance locally shrinks to ~2.56 Å. The microwave conductivity exhibiting activation-type behavior, isotope effect and anisotropy indicates that the water nanotube is a quasi one-dimensional high proton conductor. Together with the neutron experimental results, we have clarified that the proton and protonic hole are generated by the self-dissociation in some water molecules just hydrated to the carboxylate oxygen atom of trimesic acid. The Eigen-like hydrated proton and protonic hole contribute to the intrinsic proton conduction accompanying local distortions. The carrier density dominated by the intrinsic ionic equilibrium is not large, whereas the actual mobility, which is higher than 1 × 10(-2) (cm(2)/Vs), yields the present high proton conductivity.

Observation of Quasi-One Dimensional Proton Conductions in Molecular Porous Crystal [CoIII(H2bim)3](TMA)·20H2O

Triple-layered hydration structure called water nanotube (WNT) is created inside the hydrophilic nanochannel framework in [Co III (H 2 bim) 3 ](TMA)·20H 2 O. The present infrared spectral analysis for OH stretching vibrations reveals that the mobile water molecules in WNT fundamentally occupy the regular coordination tetrahedrally arranged by hydrogen bonds. The noncontact microwave experiment demonstrates that the thermal activation-type electrical conductivity along the tube axis reaches to the identical order of 10 -2 (Ω cm) -1 to the high protonic conductivity in Nafion. The pronounced isotope effect and distinct anisotropy of the conductivity prove the occurrence of quasi one-dimensional (Q1D) proton conductions through the well regulated water network.

Anomalous Water Molecules and Mechanistic Effects of Water Nanotube Clusters Confined to Molecular Porous Crystals

The movement of water molecules in the limited space present within nanoscale regions, which is different from the molecular motion of bulk water, is significantly affected by strong interfacial interactions with the surrounding outer walls. Hence, most of the water molecules that are confined to nanochannel spaces having widths less than ca. 2 nm can generally be classified together as "structural water". Since the motions of such water molecules are limited by interfacial interactions with the outer wall, the nature of structural water, which is strongly influenced by the interactions, will have different characteristics from normal water. For our investigations on the characteristics of structural water, we have developed a nanoporous crystal with a diameter of ca. 1.6 nm; it was constructed from 1-D hydrophilic channels by self-organization of the designed molecules. A tubelike three-layered water cluster, called a water nanotube (WNT), is formed in each internal channel space and is regulated by H-bonds with the outer wall. The WNT undergoes a glass transition (T(g) = 107 K) and behaves as a liquid; it freezes at 234 K and changes into an icelike nanotube cluster. In this study, the structure of the WNT is investigated through neutron structure analysis, and it is observed to stabilize by a mechanistic anchor effect of structural water. Furthermore, from neutron-scattering experiments, it is seen that a few water molecules around the center of the WNT move approximately with the same diffusion constant as those in bulk water; however, the residence time and average jump length are longer, despite the restrictions imposed by the H-bonding with structural water. The behavior of mobile water within a WNT is investigated; this can be used to elucidate the mechanism for the effect of structural water on vital functions on the cell surface.