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Yexiang Tong - One of the best experts on this subject based on the ideXlab platform.

  • Carbon/MnO(2) Double-Walled Nanotube arrays with fast ion and electron transmission for high-performance supercapacitors.
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Yexiang Tong
    Abstract:

    The novel carbon (C)/MnO2 Double-Walled Nanotube arrays (DNTAs) are designed and fabricated via template-assisted electrodeposition. The unique DNTA architectures of C/MnO2 composites with high weight fraction of MnO2 allow high electrode utilization ratio and facilitate electron and ion transmission. In the half-cell test, the hybrid C/MnO2 DNTAs as electrodes show a large specific capacitance (Csp) of 793 F/g at the scan rate of 5 mV/s, high energy/power densities, and much enhanced long-term cycle stability. After 5,000 cycles, the Csp retention of C/MnO2 DNTAs keeps ∼97%, which is much larger than 69% of the MnO2 Nanotube arrays (NTAs). The symmetrical supercapacitors (SSCs) composed of C/ MnO2 DNTAs also show the predominant performance, such as large Csp of 161 F/g and high energy density of ∼35 Wh/kg, indicating that the C/MnO2 DNTAs is a potential electrode for supercapacitors. The high order pore passages, Double-Walled structures, hollow structures, and high conductivity are responsible for the superior performance of C/MnO2 DNTAs. Such hybrid C/MnO2 DNTAs may bring new opportunities for the development of supercapacitors with superior performance.

  • carbon mno 2 Double Walled Nanotube arrays with fast ion and electron transmission for high performance supercapacitors
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Yexiang Tong
    Abstract:

    The novel carbon (C)/MnO2 Double-Walled Nanotube arrays (DNTAs) are designed and fabricated via template-assisted electrodeposition. The unique DNTA architectures of C/MnO2 composites with high weight fraction of MnO2 allow high electrode utilization ratio and facilitate electron and ion transmission. In the half-cell test, the hybrid C/MnO2 DNTAs as electrodes show a large specific capacitance (Csp) of 793 F/g at the scan rate of 5 mV/s, high energy/power densities, and much enhanced long-term cycle stability. After 5,000 cycles, the Csp retention of C/MnO2 DNTAs keeps ∼97%, which is much larger than 69% of the MnO2 Nanotube arrays (NTAs). The symmetrical supercapacitors (SSCs) composed of C/ MnO2 DNTAs also show the predominant performance, such as large Csp of 161 F/g and high energy density of ∼35 Wh/kg, indicating that the C/MnO2 DNTAs is a potential electrode for supercapacitors. The high order pore passages, Double-Walled structures, hollow structures, and high conductivity are responsible for the superior performance of C/MnO2 DNTAs. Such hybrid C/MnO2 DNTAs may bring new opportunities for the development of supercapacitors with superior performance.

  • design of polypyrrole polyaniline Double Walled Nanotube arrays for electrochemical energy storage
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Zilong Wang, Yexiang Tong
    Abstract:

    The novel hybrid polypyrrole (PPy)/polyaniline (PANI) Double-Walled Nanotube arrays (DNTAs) were designed to exploit the synergistic effects and shape effects for supercapacitive energy storage. The PPy/PANI DNTAs showed large specific capacitance (Csp) of 693 F/g at a scan rate of 5 mV/s. The PPy/PANI DNTAs also exhibited good rate capability and high long-term cycle stability (less 8% loss of the maximum specific capacitance after 1000 cycles). The synergistic effects between PPy and PANI, the shape effects of Nanotube arrays and Double-Walled nanostructures, and high utilization rate of electrode are crucial for the outstanding performance of PPy/PANI DNTAs. The large Csp, good rate capability, and high long-term cycle stability offered by the PPy/PANI DNTAs, make them promising candidate electrodes for high-performance supercapacitors.

  • Design of polypyrrole/polyaniline Double-Walled Nanotube arrays for electrochemical energy storage.
    ACS Applied Materials & Interfaces, 2013
    Co-Authors: Zilong Wang, Yexiang Tong
    Abstract:

    The novel hybrid polypyrrole (PPy)/polyaniline (PANI) Double-Walled Nanotube arrays (DNTAs) were designed to exploit the synergistic effects and shape effects for supercapacitive energy storage. The PPy/PANI DNTAs showed large specific capacitance (Csp) of 693 F/g at a scan rate of 5 mV/s. The PPy/PANI DNTAs also exhibited good rate capability and high long-term cycle stability (less 8% loss of the maximum specific capacitance after 1000 cycles). The synergistic effects between PPy and PANI, the shape effects of Nanotube arrays and Double-Walled nanostructures, and high utilization rate of electrode are crucial for the outstanding performance of PPy/PANI DNTAs. The large Csp, good rate capability, and high long-term cycle stability offered by the PPy/PANI DNTAs, make them promising candidate electrodes for high-performance supercapacitors.

Zhengxing Huang - One of the best experts on this subject based on the ideXlab platform.

  • interfacial thermal resistance of 2d and 1d carbon hexagonal boron nitride van der waals heterostructures
    Carbon, 2016
    Co-Authors: Zhenan Tang, Zhengxing Huang
    Abstract:

    Abstract The newly emerging graphene/hexagonal boron nitride (h-BN) van der Waals heterostructures has attracted much research interest due to its new properties and functions for practical applications in nanodevices. In this work, molecular dynamics simulations are performed to study the interfacial thermal resistance (ITR) of a graphene/h-BN bilayer system as well as its one-dimensional counterpart, a concentric CNT/BNNT Double-Walled Nanotube, based on the lumped capacity model. The calculated ITR is in an order of magnitude of 10−7–10−6 Km2/W and it monotonically decreases with temperature and interlayer/intertube coupling strength. It is believed that the ITR between graphene and h-BN is reduced through the enhancement of the coupling strength instead of the geometrical overlap of the phonon modes. Heat flux direction has no effect on the ITR of the graphene/h-BN bilayer, however, radial thermal rectification is found in the CNT/BNNT composite, with a largest thermal rectification factor of ∼90%. Thermal energy always prefers to transport from the outer Nanotube towards the inner Nanotube in the CNT/BNNT system over the opposite direction no matter the outer Nanotube is CNT or BNNT because the outer Nanotube has more high-frequency phonons than that of the inner Nanotube in the CNT/BNNT system.

  • Interfacial thermal resistance of 2D and 1D carbon/hexagonal boron nitride van der Waals heterostructures
    Carbon, 2016
    Co-Authors: Zhenan Tang, Zhengxing Huang
    Abstract:

    Abstract The newly emerging graphene/hexagonal boron nitride (h-BN) van der Waals heterostructures has attracted much research interest due to its new properties and functions for practical applications in nanodevices. In this work, molecular dynamics simulations are performed to study the interfacial thermal resistance (ITR) of a graphene/h-BN bilayer system as well as its one-dimensional counterpart, a concentric CNT/BNNT Double-Walled Nanotube, based on the lumped capacity model. The calculated ITR is in an order of magnitude of 10−7–10−6 Km2/W and it monotonically decreases with temperature and interlayer/intertube coupling strength. It is believed that the ITR between graphene and h-BN is reduced through the enhancement of the coupling strength instead of the geometrical overlap of the phonon modes. Heat flux direction has no effect on the ITR of the graphene/h-BN bilayer, however, radial thermal rectification is found in the CNT/BNNT composite, with a largest thermal rectification factor of ∼90%. Thermal energy always prefers to transport from the outer Nanotube towards the inner Nanotube in the CNT/BNNT system over the opposite direction no matter the outer Nanotube is CNT or BNNT because the outer Nanotube has more high-frequency phonons than that of the inner Nanotube in the CNT/BNNT system.

Horacio D. Espinosa - One of the best experts on this subject based on the ideXlab platform.

  • experimental computational study of shear interactions within Double Walled carbon Nanotube bundles
    Nano Letters, 2012
    Co-Authors: Tobin Filleter, Mohammad Naraghi, Scott Yockel, Jeffrey T Paci, Owen C Compton, Maricris Lodriguito Mayes, Sonbinh T Nguyen, George C Schatz, Horacio D. Espinosa
    Abstract:

    The mechanical behavior of carbon Nanotube (CNT)-based fibers and nanocomposites depends intimately on the shear interactions between adjacent tubes. We have applied an experimental-computational approach to investigate the shear interactions between adjacent CNTs within individual Double-Walled Nanotube (DWNT) bundles. The force required to pull out an inner bundle of DWNTs from an outer shell of DWNTs was measured using in situ scanning electron microscopy methods. The normalized force per CNT–CNT interaction (1.7 ± 1.0 nN) was found to be considerably higher than molecular mechanics (MM)-based predictions for bare CNTs (0.3 nN). This MM result is similar to the force that results from exposure of newly formed CNT surfaces, indicating that the observed pullout force arises from factors beyond what arise from potential energy effects associated with bare CNTs. Through further theoretical considerations we show that the experimentally measured pullout force may include small contributions from carbonyl fu...

  • A Multiscale Study of High Performance Double-Walled Nanotube−Polymer Fibers
    ACS Nano, 2010
    Co-Authors: Mohammad Naraghi, Tobin Filleter, A.p. Moravsky, Mark A Locascio, Raouf O. Loutfy, Horacio D. Espinosa
    Abstract:

    The superior mechanical behavior of carbon Nanotubes (CNT) and their electrical and thermal functionalities has motivated researchers to exploit them as building blocks to develop advanced materials. Here, we demonstrate high performance Double-Walled Nanotube (DWNT)−polymer composite yarns formed by twisting and stretching of ribbons of randomly oriented bundles of DWNTs thinly coated with polymeric organic compounds. A multiscale in situ scanning electron microscopy experimental approach was implemented to investigate the mechanical performance of yarns and isolated DWNT bundles with and without polymer coatings. DWNT−polymer yarns exhibited significant ductility of ∼20%, with energy-to-failure of as high as ∼100 J g−1, superior to previously reported CNT-based yarns. The enhanced ductility is not at the expense of strength, as yarns exhibited strength as high as ∼1.4 GPa. In addition, the significance of twisting on the densification of yarns and corresponding enhancement in the lateral interactions be...

  • a multiscale study of high performance Double Walled Nanotube polymer fibers
    ACS Nano, 2010
    Co-Authors: Mohammad Naraghi, Tobin Filleter, A.p. Moravsky, Mark A Locascio, Raouf O. Loutfy, Horacio D. Espinosa
    Abstract:

    The superior mechanical behavior of carbon Nanotubes (CNT) and their electrical and thermal functionalities has motivated researchers to exploit them as building blocks to develop advanced materials. Here, we demonstrate high performance Double-Walled Nanotube (DWNT)−polymer composite yarns formed by twisting and stretching of ribbons of randomly oriented bundles of DWNTs thinly coated with polymeric organic compounds. A multiscale in situ scanning electron microscopy experimental approach was implemented to investigate the mechanical performance of yarns and isolated DWNT bundles with and without polymer coatings. DWNT−polymer yarns exhibited significant ductility of ∼20%, with energy-to-failure of as high as ∼100 J g−1, superior to previously reported CNT-based yarns. The enhanced ductility is not at the expense of strength, as yarns exhibited strength as high as ∼1.4 GPa. In addition, the significance of twisting on the densification of yarns and corresponding enhancement in the lateral interactions be...

Célia T. Sousa - One of the best experts on this subject based on the ideXlab platform.

  • Double-Walled iron oxide Nanotubes via selective chemical etching and Kirkendall process
    Scientific Reports, 2019
    Co-Authors: João Azevedo, M. P. Fernández-garcía, César Magén, Adélio Mendes, João P. Araújo, Célia T. Sousa
    Abstract:

    Double-Walled oxide Nanotube structures are interesting for a wide range of applications, from photocatalysis to drug delivery. In this work, a progressive oxidation method to fabricate Double-Walled Nanotube structures is reported in detail. The approach is based on the electrodeposition of metallic iron nanowires, in porous alumina templates, followed by a selective chemical etching, nanoscale Kirkendall effect, a fast oxidation and out-diffusion of the metallic core structure during thermal annealing. To validate the formation mechanism of such core-shell structure, chemical composition and atomic structure were assessed. The resulting hematite Nanotubes have a high degree of uniformity, along several microns, and a nanoscopic Double-Walled structure.

Zhenan Tang - One of the best experts on this subject based on the ideXlab platform.

  • interfacial thermal resistance of 2d and 1d carbon hexagonal boron nitride van der waals heterostructures
    Carbon, 2016
    Co-Authors: Zhenan Tang, Zhengxing Huang
    Abstract:

    Abstract The newly emerging graphene/hexagonal boron nitride (h-BN) van der Waals heterostructures has attracted much research interest due to its new properties and functions for practical applications in nanodevices. In this work, molecular dynamics simulations are performed to study the interfacial thermal resistance (ITR) of a graphene/h-BN bilayer system as well as its one-dimensional counterpart, a concentric CNT/BNNT Double-Walled Nanotube, based on the lumped capacity model. The calculated ITR is in an order of magnitude of 10−7–10−6 Km2/W and it monotonically decreases with temperature and interlayer/intertube coupling strength. It is believed that the ITR between graphene and h-BN is reduced through the enhancement of the coupling strength instead of the geometrical overlap of the phonon modes. Heat flux direction has no effect on the ITR of the graphene/h-BN bilayer, however, radial thermal rectification is found in the CNT/BNNT composite, with a largest thermal rectification factor of ∼90%. Thermal energy always prefers to transport from the outer Nanotube towards the inner Nanotube in the CNT/BNNT system over the opposite direction no matter the outer Nanotube is CNT or BNNT because the outer Nanotube has more high-frequency phonons than that of the inner Nanotube in the CNT/BNNT system.

  • Interfacial thermal resistance of 2D and 1D carbon/hexagonal boron nitride van der Waals heterostructures
    Carbon, 2016
    Co-Authors: Zhenan Tang, Zhengxing Huang
    Abstract:

    Abstract The newly emerging graphene/hexagonal boron nitride (h-BN) van der Waals heterostructures has attracted much research interest due to its new properties and functions for practical applications in nanodevices. In this work, molecular dynamics simulations are performed to study the interfacial thermal resistance (ITR) of a graphene/h-BN bilayer system as well as its one-dimensional counterpart, a concentric CNT/BNNT Double-Walled Nanotube, based on the lumped capacity model. The calculated ITR is in an order of magnitude of 10−7–10−6 Km2/W and it monotonically decreases with temperature and interlayer/intertube coupling strength. It is believed that the ITR between graphene and h-BN is reduced through the enhancement of the coupling strength instead of the geometrical overlap of the phonon modes. Heat flux direction has no effect on the ITR of the graphene/h-BN bilayer, however, radial thermal rectification is found in the CNT/BNNT composite, with a largest thermal rectification factor of ∼90%. Thermal energy always prefers to transport from the outer Nanotube towards the inner Nanotube in the CNT/BNNT system over the opposite direction no matter the outer Nanotube is CNT or BNNT because the outer Nanotube has more high-frequency phonons than that of the inner Nanotube in the CNT/BNNT system.