Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.

Investigating metal-organic frameworks (MOFs) as water adsorbents has drawn increasing attention for their potential in energy-related applications such as water production and heat transformation. A specific MOF, MIL-100(Fe), is of particular interest for its large adsorption capacity with the occurrence of water condensation at a relatively low partial pressure. In the synthesis of MIL-100(Fe), depending on the reactants, structures with varying anion terminals (e.g., F, Cl, or OH) on the metal trimer have been reported. In this study, we employed molecular simulations and density functional theory calculations for investigating the water adsorption behaviors and the relative structural stability of MIL-100(Fe) with different anions. We also proposed a possible defective structure and explored its water adsorption properties. The results of this study are in good agreement with the experimental measurements and are in support of the observations reported in the literature. Understanding the spatial configurations and energetics of water molecules in these materials has also shed light on their adsorption mechanism at the atomic level.

Water shortage has become a critical issue. To facilitate the large-scale deployment of reverse-osmosis water desalination to produce fresh water, discovering novel membranes is essential. Here, we computationally demonstrate the great potential of single-walled aluminosilicate nanotubes (AlSiNTs), materials that can be synthesized through scalable methods, in desalination. State-of-the-art molecular dynamics simulations were employed to investigate the desalination performance and structure-performance relationship of AlSiNTs. Free energy profiles, passage time distribution, and water density map were also analyzed to further understand the dependence of transport properties on diameter and water dynamics in the nanotubes. AlSiNTs with an inner diameter of 0.86 nm were found to fully reject NaCl ions while allowing orders of magnitude higher water fluxes compared to currently available reverse osmosis membranes, providing opportunities in water desalination.

Single-walleda luminosilicate nanotubes (AlSiNTs) are expected to possess mechanical strength comparablet o that of single-walled carbon nanotubes (SWCNTs). Most existing theoretical studies on the mechanical properties of AlSiNTsa re based on defect-free models, despite the fact that experimental resultsh ave revealed av ariety of defectsi nA lSiNTs. Herein we developed am ethod for the modeling of defective AlSiNTst oe nable the quantitative investigation of relationships among defects tructures, structural stability, and mechanical properties of AlSiNTs. The defect structures dealt with in the proposed modelsa re based on experimental findings. Our assessment of the stability andm echanical strength of nanotubes is based on multiscale computational tools, including density functional theory,m olecular modeling, and nanoscale continuum modeling. Our study also identifiedt he defects tructure with the most pronounced impact on the stability and mechanical properties of AlSiNTs.

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