Multiscale, multiphase numerical modeling is used to explain the mechanisms of effective control of chirality distributions of single-walled carbon nanotubes in direct plasma growth and suggest effective approaches to further improvement. The model includes an unprecedented combination of the plasma sheath, ion/radical transport, species creation/loss, plasma-surface interaction, heat transfer, surface/bulk diffusion, graphene layer nucleation, and bending/lift-off modules. It is shown that the constructive interplay between the plasma and the Gibbs-Thomson effect can lead to the effective nucleation and lift-off of small graphene layers on small metal catalyst nanoparticles. As a result, much thinner nanotubes with narrower chirality distributions can nucleate at much lower process temperatures and pressures compared to thermal CVD. This approach is validated by a host of experimental results, substantially reduces the amounts of energy and atomic matter required for the nanotube growth, and can be extended to other nanoscale structures and materials systems, thereby nearing the ultimate goal of energy- and matter-efficient nanotechnology.
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http://dx.doi.org/10.1021/nn2030989 | DOI Listing |
J Chem Theory Comput
January 2025
Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, Texas 79968, United States.
In this work, we describe a computational tool designed to determine the local dielectric constants (ε) of charge-neutral heterogeneous systems by analyzing dipole moment fluctuations from molecular dynamics (MD) trajectories. Unlike conventional methods, our tool can calculate dielectric constants for dynamically evolving selections of molecules within a defined region of space, rather than for fixed sets of molecules. We validated our approach by computing the dielectric constants of TIP3P water nanospheres, achieving results consistent with literature values for bulk water.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Mechanical & Vehicle Engineering, Linyi University, Linyi, Shandong 276000, China.
Molecular dynamics simulations demonstrate that regular conical helices of poly(-phenylene) (PPP) chains can be constructed inside the confined space of single-walled carbon nanocones (CNCs). The translocation displacement of the PPP chain combined with the change of the system total potential energy including each energy component and structural parameters of the formed conical helix is discussed to deeply explore the microstructure evolution, driving forces and dynamic mechanisms. In addition, the influence of chain length, cone angle, temperature, chain number, linked position of benzene rings and the form of Lennard-Jones potential on the helical encapsulation is further studied.
View Article and Find Full Text PDFEnviron Toxicol Chem
January 2025
School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, PR China.
In silico methods are increasingly important in predicting the ecotoxicity of engineered nanomaterials (ENMs), encompassing both individual and mixture toxicity predictions. It is widely recognized that ENMs trigger oxidative stress effects by generating intracellular reactive oxygen species (ROS), serving as a key mechanism in their cytotoxicity studies. However, existing in silico methods still face significant challenges in predicting the oxidative stress effects induced by ENMs.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department of Materials Science, Tokai University, Hiratsuka 259-1292, Kanagawa, Japan.
Semiconducting single-walled carbon nanotubes (SWCNTs) are significantly attractive for thermoelectric generators (TEGs), which convert thermal energy into electricity via the Seebeck effect. This is because the characteristics of semiconducting SWCNTs are perfectly suited for TEGs as self-contained power sources for sensors on the Internet of Things (IoT). However, the thermoelectric performances of the SWCNTs should be further improved by using the power sources.
View Article and Find Full Text PDFPolymers (Basel)
January 2025
Department of Materials Science and Engineering, Gachon University, Seongnam 13120, Republic of Korea.
Single-walled carbon nanotubes (SWNTs) exhibit distinct electronic properties, categorized as metallic or semiconducting, determined by their chirality. The precise and selective separation of these electronic types is pivotal for advancing nanotechnology applications. While conventional gel chromatography has been widely employed for large-scale separations, its limitations in addressing microscale dynamics and electronic-type differentiation have persisted.
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