Controlled Manipulation of Giant Hybrid Inorganic Nanowire Assemblies

The ultimate goal of nanotechnology is the design and fabrication of nanosize building blocks with multiple functionalities and their assembly into large-scale functional structures that can be controllably manipulated. Here we show that hybrid inorganic multisegmented nanowires, with hydrophobic carbon nanotube tails and hydrophilic metal nanowire heads, allow the assembly and manipulation of massive ordered structures in solution, reminiscent of the organic molecular micellar assembly. Further, properly designed assemblies can be manipulated using external stimuli such as magnetic field and light. The hybrid nanowires can have multiple segments including magnetic components, allowing the assembly to be manipulated by external magnetic field. The assembled structures can also be manipulated by modifying the hydrophobicity of the respective components via chemical functionalization and optical irradiation. This approach brings the concept of environment sensitive self-assembling nanomaterials closer to reality

Controlled Manipulation of Giant Hybrid Inorganic Nanowire Assemblies

The ultimate goal of nanotechnology is the design and fabrication of nanosize building blocks with multiple functionalities and their assembly into large-scale functional structures that can be controllably manipulated. Here we show that hybrid inorganic multisegmented nanowires, with hydrophobic carbon nanotube tails and hydrophilic metal nanowire heads, allow the assembly and manipulation of massive ordered structures in solution, reminiscent of the organic molecular micellar assembly. Further, properly designed assemblies can be manipulated using external stimuli such as magnetic field and light. The hybrid nanowires can have multiple segments including magnetic components, allowing the assembly to be manipulated by external magnetic field. The assembled structures can also be manipulated by modifying the hydrophobicity of the respective components via chemical functionalization and optical irradiation. This approach brings the concept of environment sensitive self-assembling nanomaterials closer to reality

Controlled Manipulation of Giant Hybrid Inorganic Nanowire Assemblies

The ultimate goal of nanotechnology is the design and fabrication of nanosize building blocks with multiple functionalities and their assembly into large-scale functional structures that can be controllably manipulated. Here we show that hybrid inorganic multisegmented nanowires, with hydrophobic carbon nanotube tails and hydrophilic metal nanowire heads, allow the assembly and manipulation of massive ordered structures in solution, reminiscent of the organic molecular micellar assembly. Further, properly designed assemblies can be manipulated using external stimuli such as magnetic field and light. The hybrid nanowires can have multiple segments including magnetic components, allowing the assembly to be manipulated by external magnetic field. The assembled structures can also be manipulated by modifying the hydrophobicity of the respective components via chemical functionalization and optical irradiation. This approach brings the concept of environment sensitive self-assembling nanomaterials closer to reality

Design and Characterization of Three-Dimensional Carbon Nanotube Foams

We demonstrate a new method that makes use of colloidal silica templates to fabricate porous three-dimensional architectures of carbon nanotubes (CNTs). CNTs were grown on monolayered and multilayered structures of colloidal silica using chemical vapor deposition. Porous CNT membranes and three-dimensional carbon nanotube foams were obtained by treating these silica-CNTs structures with HF. The membranes and foams of CNT so obtained were chemically and mechanically stable and were characterized by using scanning electron microscopy and energy dispersive spectroscopy

Large Area-Aligned Arrays from Direct Deposition of Single-Wall Carbon Nanotube Inks

Single-wall carbon nanotubes (SWNTs) are well dispersed in water using a polymer, polyvinylpyrrolidone (PVP), a surfactant, sodium dodecyl benzene sulfonate (SDBS), and brief low-power sonication. The concentration of these pristine SWNT dispersions are quite high, approaching 1 g/L, and remain stable over several months. These suspensions can be used as a printable conductive material and were used to create novel self-assembled SWNT arrays which are highly aligned. Suspensions of pristine SWNTs in water enable their application to aqueous chemistry, reduce environmental impact from use of organic solvents, and create suspensions which are compatible with materials sensitive to harsh solvents. Avoiding covalent functionalization allows for the SWNTs to have optimum mechanical and electronic properties and maintain lengths of several micrometers

Fast Vortex-Assisted Self-Assembly of Carbon Nanoparticles on an Air–Water Interface

In this work a self-assembly technique is presented, allowing the fast formation of carbon black thin films. It consists in the controlled addition of a stable carbon material’s dispersion over the water surface, disturbed by a vortex. The vortex, although not essential for the film formation, was found to drastically improve film homogeneity. A physical chemical study concerning how several parameters could be used to tune film properties was also conducted. The self-assembled films, which can be picked up in any hydrophilic substrate, showed a good electrical conductivity and a high optical transparency. As an application example, films about 200 nm thick were employed as supercapacitor electrodes

Lipid-Based Nanotubes as Functional Architectures with Embedded Fluorescence and Recognition Capabilities

A limited combinatorial strategy was used to synthesize a small library of soft lipid-based materials ranging from structurally unordered fibers to highly uniform nanotubes. The latter nanotubes are comprised of a bilayer structure with interdigitated alkyl chains associated through hydrophobic interactions. These tubes contain accessible 2,6-diaminopyridine linkers that can interact with thymidine and related nucleosides through multipoint hydrogen bonding, thereby quenching the intrinsic fluorescence of the aromatic linker. These results are the first example of a systematic strategy to design functional lipid nanotubes with precise structural and functional features

Coaxial MnO₂/Carbon Nanotube Array Electrodes for High-Performance Lithium Batteries

Coaxial manganese oxide/carbon nanotube (CNT) arrays deposited inside porous alumina templates were used as cathodes in a lithium battery. Excellent cyclic stability and capacity of MnO2/CNT coaxial nanotube electrodes resulted from the hybrid nature of the electrodes with improved electronic conductivity and dual mechanism of lithium storage. The reversible capacity of the battery was increased by an order compared to template grown MnO2 nanotubes, making them suitable electrodes for advanced Li ion batteries

LiNi_1/3Co_1/3Mn_1/3O₂–Graphene Composite as a Promising Cathode for Lithium-Ion Batteries

The use of graphene as a conductive additive to enhance the discharge capacity and rate capability of LiNi1/3Co1/3Mn1/3O2 electrode material has been demonstrated. LiNi1/3Co1/3Mn1/3O2 and its composite with graphene (90:10 wt %) were prepared by microemulsion and ball-milling techniques, respectively. The structural and morphological features of the prepared materials were investigated with powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Characterization techniques depict single-phase LiNi1/3Co1/3Mn1/3O2 with particle sizes in the range of 220–280 nm. Electrochemical studies on LiNi1/3Co1/3Mn1/3O2 and LiNi1/3Co1/3Mn1/3O2–graphene were conducted using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy methods by constructing a lithium half-cell. Cyclic voltammograms show the well-defined redox peaks corresponding to Ni2+/Ni4+. Charge–discharge tests were performed at different C rates: 0.05, 1, and 5 between 2.5 and 4.4 V. The results indicate the better electrochemical performance of the LiNi1/3Co1/3Mn1/3O2–graphene composite in terms of high discharge capacity (188 mAh/g), good rate capability, and good cycling performance compared to LiNi1/3Mn1/3Co1/3O2. The improved electrochemical performance of the LiNi1/3Co1/3Mn1/3O2–graphene composite is attributed to a decrease in the charge-transfer resistance

Kinetics for the Synthesis Reaction of Aligned Carbon Nanotubes: A Study Based on in situ Diffractography

Single-slit laser diffractography was used to image the growth of carbon nanotubes. A silicon dioxide slit with a minimum width of 150 μm was prepared and positioned inside a chemical vapor deposition (CVD) reactor in alignment with a laser source. Carbon nanotubes were grown inside the slit width, producing corresponding changes in the diffraction pattern due to the optical opacity of these structures and to their high density and alignment. Changes in the diffraction pattern were recorded and used for the direct measurement of nanotube growth. The results show an exponential increase of length vs time for 45 min experiments, best fit with a double exponential function, which is interpreted in terms of the concurrence of base-growth and tip-growth modes for successive catalyst particles. Scanning electron microscopy confirms the diffractographic data at a high level of precision. The innovation brought by this in situ method to the kinetic study of nanotube synthesis is discussed and compared to a posteriori studies based solely on microscopy for a range of different nanotube lengths