Sishen Xie

Large-Scale Synthesis of Aligned Carbon Nanotubes

Large-scale synthesis of aligned carbon nanotubes was achieved by using a method based on chemical vapor deposition catalyzed by iron nanoparticles embedded in mesoporous silica. Scanning electron microscope images show that the nanotubes are approximately perpendicular to the surface of the silica and form an aligned array of isolated tubes with spacings between the tubes of about 100 nanometers. The tubes are up to about 50 micrometers long and well graphitized. The growth direction of the nanotubes may be controlled by the pores from which the nanotubes grow.

Highly Stretchable, Integrated Supercapacitors Based on Single-Walled Carbon Nanotube Films with Continuous Reticulate Architecture

Highly stretchable, integrated, single-walled carbon nanotube (SWCNT) film supercapacitors are prepared by combining directly grown SWCNT films with continuous reticulate architecture with polydimethylsiloxane with enhanced prestrain. The performance of the prepared stretchable supercapacitors remains nearly unchanged even during the stretching process under 120% strain.

Mechanical and physical properties on carbon nanotube

Abstract The aligned and very long carbon nanotubes were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. Aligned and isolated carbon nanotubes with high density, high purity and uniform diameters were achieved. Mechanical and physical property characterizations, such as tensile strength, Youngs modulus, thermal conductivity and third-order optical nonlinearity, were carried out on the aligned and long tubes. The results were discussed with the microstructure of the carbon nanotubes.

Nanostructured graphene composite papers for highly flexible and foldable supercapacitors.

Reduced graphene oxide (rGO) and polyaniline (PANI) assemble onto the surface of cellulose fibers (CFs) and into the pores of CF paper, to form a hierarchical nanostructured PANI-rGO/CF composite paper. Based on these composite papers, flexible and foldable all-solid-state supercapacitors are achieved.

Carbon Nanotubes Conjugated to Tumor Lysate Protein Enhance the Efficacy of an Antitumor Immunotherapy

The biomedical applications of carbon nanotubes (CNTs) have attracted deep interest in recent years. Antitumor immunotherapy has the potential to improve the prognosis of cancer treatment but the efficacy of current immunotherapy generally needs further improvement. Multi-walled CNTs conjugated to tumor lysate protein are investigated as to whether they would enhance the efficacy of an immunotherapy employing a tumor-cell vaccine in a mouse model bearing the H22 liver cancer. The tumor cure rate is found to be markedly improved by CNTs conjugated to tumor lysate protein. The cellular antitumor immune reaction is also enhanced. Moreover, the observed antitumor immune response is relatively specific against the tumor intended for treatment. These findings suggest that CNTs may have a prospective role in the development of new antitumor immunotherapies.

High-Strength Composite Fibers: Realizing True Potential of Carbon Nanotubes in Polymer Matrix through Continuous Reticulate Architecture and Molecular Level Couplings

Carbon nanotubes have unprecedented mechanical properties as defect-free nanoscale building blocks, but their potential has not been fully realized in composite materials due to weakness at the interfaces. Here we demonstrate that through load-transfer-favored three-dimensional architecture and molecular level couplings with polymer chains, true potential of CNTs can be realized in composites as initially envisioned. Composite fibers with reticulate nanotube architectures show order of magnitude improvement in strength compared to randomly dispersed short CNT reinforced composites reported before. The molecular level couplings between nanotubes and polymer chains results in drastic differences in the properties of thermoset and thermoplastic composite fibers, which indicate that conventional macroscopic composite theory fails to explain the overall hybrid behavior at nanoscale.

Gold nanorod-seeded growth of silver nanostructures: From homogeneous coating to anisotropic coating

Single crystalline gold nanorods (Au NRs) dominated by {110} side facets were employed as seeds to tailor the deposition of Ag. Apart from homogeneous coating, anisotropic coating of Ag was observed and resulted in an orange slice-like shape for the Au@Ag nanocrystal. Different growth rates for the {110} side facets were responsible for this shape: among the four {110} facets, two of the neighboring {110} facets grew more quickly and another two grew more slowly, thus inducing the anisotropic deposition of Ag around the Au NR. This growth behavior is believed to be a consequence of competition between the strong stabilization of cetyltrimethylammomium bromide (CTAB) molecules to the {110} facets of Ag and minimization of the overall surface energy. Although the reason for the anisotropic coating remains to be clarified, our results lead to one important conclusion: The interaction of CTAB and metal can be utilized to tune the shapes of bimetallic structures.

Double wall carbon nanotubes promoted by sulfur in a floating iron catalyst CVD system

Double wall carbon nanotubes (DWCNTs) were mass-produced by pyrolizing C2H2 at the temperature range of 900–1100 °C on a floating iron catalyst with sulfur promoted. Our experiments indicated that the growth of DWCNTs was strongly dependent on the sulfur addition, and without sulfur only single wall carbon nanotubes (SWCNTs) were produced. The outer tube diameters of DWCNTs observed by high resolution electron microscopy (HRTEM) vary from 1.05 to 2.89 nm, and the inner tube diameters vary from 0.40 to 2.19 nm. The effect mechanism of sulfur to the growth of DWCNTs was discussed.

Controlled synthesis of monodispersed CuO nanocrystals

Controlling the size, shape and structure of nanocrystals is technologically important because of the strong effect of size and shape on optical, electrical, and catalytic properties. Monodispersed nanocrystals of copper oxide were prepared by the precipitation?pyrolysis method. By controlling the starting materials, reactive concentration and annealing temperature, we can obtain spherical monodispersed CuO nanocrystals of different sizes or rodlike CuO nanocrystals. The particle sizes of CuO monodispersed nanocrystals can be tuned in the range between and 30?nm. The products have been characterized by x-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and the UV?visible absorption spectrum. The absorption spectra of CuO nanocrystals show clear evidence of the quantum size effect. The possible formation mechanism of monodispersed CuO nanocrystals is discussed.

Synthesis, characterizations, and physical properties of carbon nanotubes coated by conducting polypyrrole

A new type of carbon nanotube (CNT) (diameter of <100 nm) coated by conducting polypyrrole (PPY) was synthesized by in situ polymerization on CNTs. The structure of the resulting complex nanotubes (CNT-PPY) was characterized by elemental analysis, X-ray photoelectron spectroscopy, Raman spectra, and X-ray diffraction. These indicated no significant chemical interaction between PPY and the CNT. The electrical, magnetic, and thermal properties of the complex nanotubes were measured and showed the physical properties of the CNTs were modified by conducting PPY.