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Abstract: The performances of freestanding carbon nanotube (buckypaper) and polymer-intercalated buckypaper electrodes in an electroanalytical chemistry context were evaluated via analysis of direct current and Fourier Transform large-amplitude alternating current voltammograms derived from the ferrocenemonocarboxylic acid (FMCA0/+), ruthenium hexamine ([Ru(NH3)6]3+/2+) and ferricyanide ([Fe(CN)6]3−/4−) redox couples. The composite polymer-intercalated buckypaper electrodes exhibit substantially superior Faradaic-to-capacitive background charging current ratios under both dc and ac conditions compared and display close to ideal voltammetry for all three processes. A significant difference was detected in mid-point potentials determined by cyclic voltammetry at buckypaper and polymer-intercalated buckypaper electrodes, commensurate with different mass transport mechanisms. It is proposed that the porosity of the buckypaper gives rise to a restricted diffusion model of mass transport within the pores and a large electrode over that generates a large capacitance current. Thus, polymer intercalation is required to achieve high quality electroanalytical performance. Simulations of voltammograms obtained at porous polymer-intercalated buckypaper electrodes are consistent with the composite electrodes consisting of a randomly arranged array of nano-/micro-electrode domains, implying that significant surface heterogeneity is present. However, under slow scan rate conditions, when significant overlap of diffusion layers occurs, voltammograms may be approximately interpreted in terms of a linear diffusion based mass transport model. [Copyright &y& Elsevier]

Abstract: Both single-wall or multi-wall nanotube growth result in a soot-like material that contains the desired product. The selective recovery of the nanotube product from this soot still represents a challenge. Methods to date either result in chemical modification of the nanotubes themselves, are time consuming or use expensive to produce polymers. Using a variety of biomolecules, we have been able to selectively suspend multi-wall carbon nanotubes in aqueous solutions while leaving behind the extraneous by-products in the precipitate. At comparable biomolecule to soot ratios, all biomolecules selectively retained more nanotubes than an organic polymer previously used to purify multi-wall nanotubes (PmPV—poly m-phenylene-co-2,5-dioctoxy-p-phenylenevinylene). The highest recovery as determined by Electron Paramagnetic Resonance was 56% of the available nanotubes. The method provides a simple, one-step, non-destructive purification process that facilitates the formation of pure multi-wall carbon nanotube containing biodispersions. [Copyright &y& Elsevier]

Carbon nanotubes (CNTs) were stabilized in solution through sonication-induced polymerization of acrylated epoxidized soybean oil (AESO) monomer. Transmission electron microscopy and atomic force microscopy showed that the resulting polymer coatings of nanotubes in solution were approximately 10–30 nm in thickness. Raman spectroscopy suggests that AESO intercalates Nanocyl bundles and coats the exterior of HiPco bundles. Using sonication a stable dispersion of as-produced carbon nanotube powder was formed. Mechanical measurements on macroscale composites samples showed modulus enhancement consistent with a lower bound rule of mixtures. [ABSTRACT FROM AUTHOR]

Abstract: The attachment of mouse immunoglobulin G (IgG) and anti-mouse IgG antibodies onto carbon nanotubes (CNTs), using either non-covalent or covalent means was investigated. The resultant CNTs were characterised using a variety of techniques including enzyme-linked and fluorescence-linked immunoassays, UV–visible-NIR and Raman spectroscopy, transmission electron microscopy and cyclic voltammetry. TEM images of the adsorbed antibody on the CNTs show that the covalent modification approach was successful, whereas the non-covalent approach resulted in no electrochemically detectable labelled antibody. Direct electrical communication between CNTs covalently linked to peroxidase-labelled antibodies was observed during cyclic voltammetry, which suggests applications in developing carbon-nanotube-based immunosensors. [Copyright &y& Elsevier]

Multi-wall carbon nanotubes (MWCNTs)/polyaniline (PANI)/polyethersulfone (PES) membranes were fabricated by incorporation of in-situ polymerised MWCNTs/PANI complex for effective removal of natural organic matter (NOM) in water. The membrane showed high permeability (1400 L/m 2 /h (LMH)/bar), which is 30 times greater than the PES membrane. High NOM rejection rate (80%) was also observed for the composite membrane, which is 4 times higher than PES membrane. This superior performance is attributed to the synergetic effect of increased porosity, narrow pore size distribution and hydrophilicity, and positively charged of the membranes by the inclusion of MWCNTs/PANI complex. MWCNTs/PANI electron transfer complex successfully engineered chemical/physical properties of the membrane in order to have high NOM adsorption capacity and fast water flux. It is suggested that enhanced adsorption capacity is attributed to the electrostatic interaction between NOM and the membrane surface. Key factors contributing to the fast water flux and removal mechanism were covered in depth by characterization of physical and chemical properties of the membrane. The membrane demonstrated 100% water flux recovery and 65% total fouling ratio after cleaning with 0.1 M HCl/0.1 M NaOH solution for 1 h. [ABSTRACT FROM AUTHOR]

A novel chemical method was developed to graft carbon nanotubes (CNTs) onto carbon fiber (CF) by direct covalent bonding to form a CNT–CF hierarchical reinforcing structure. The grafting via ester linkage (formed at a low temperature of 70 °C without using any contaminating catalyst or coupling agent) was evidenced by SEM, FTIR, RAMAN, XPS and XRD spectroscopy. The CNT failure stress obtained from in situ SEM pulling out experiments varied from 25 to 31 GPa, depending on the grafting reaction conditions. CNT fracture was the only breaking mechanism observed from the pulling out experiments indicating an existence of a strong carbon–carbon covalent bonding at the CNT–CF interface and the real grafting strength was actually higher than the measured failure stress. This high grafting strength can significantly increase the interfacial and impact properties desirable in next generation advanced aerospace composite structures. Further, the CNT attachments on CF led to increased electrochemical capacitance properties by rapid ion diffusion through active CNT sites and defects created during grafting. The fibrous film of CNT–CF exhibits a specific capacitance that is 3.5 times greater than that of CF, indicating substantial promise as a material for fabricating textile supercapacitors with superior strength, flexibility and performance. [ABSTRACT FROM AUTHOR]

Non-covalent attachment of light harvesting molecules to carbon nanomaterials has the potential to open up new hybrid nanostructures. By using non-covalent methods, defects are not introduced into the graphitic carbon backbone; therefore, the conductive properties of the supporting carbon are preserved, enabling charge transfer between the molecule and the carbon support. Here we demonstrate that a simple solution mixing process can produce novel, non-covalent hybrids of chlorophyll and two different nanocarbons; carbon nanotubes and graphene platelets, that demonstrate self assembly and charge transfer. These hybrids display a photoresponse even as thin films, and have improved characteristics in the presence of a hydrogel electrolyte. [ABSTRACT FROM AUTHOR]

Abstract: A new continuously aligned carbon nanotubes (ACNTs) reinforced epoxy composite was fabricated by wetting as-grown arrays of ACNTs. The uniform distribution of ACNTs in the epoxy composites was confirmed by high magnification scanning electron microscopy observations. Owing to its load-transfer-favored structure, 1.1vol.% ACNTs achieved orders of magnitude higher improvement in the wear resistance of epoxy composite compared to randomly dispersed CNTs in epoxy reported before. The research demonstrated for the first time that the use of ACNTs alone can achieve significant improvement in the wear resistance of epoxy for applications, and the specific wear rate under normal direction was stable at ∼10−6 mm3/Nm with the sliding conditions varying from 0.4 to 2.5MPam/s. Further, the experimental results showed that the wear performance of ACNT/epoxy composite is highly dependent on the orientation of the ACNTs relative to the sliding direction. In particular, it was found that ACNTs achieved the highest improvement in wear resistance under normal orientation whereas the least improvement was observed under parallel direction. The results are different from that of carbon fiber reinforced epoxy composites, indicating different wear mechanisms. Based on microscopic observations, new ACNTs related wear mechanisms were further proposed and discussed. [Copyright &y& Elsevier]

Abstract: A simple, surfactant-free assembly process was used to prepare multi-wall carbon nanotube (CNT) buckypapers using a highly efficient purification, sonication, and filtration process. To achieve effective dispersion of CNT into ethanol, a minimum 5-min sonication time was required. Here, we fabricated a buckypaper with pore size of 41±10nm and porosity of 72.9% with a 10-min sonication. The as-prepared buckypaper was used as a membrane for humic acid (HA) removal from water. During purification process, carboxylic and hydroxylic functional groups were introduced onto the CNT surface. The functional groups increased the hydrophilicity of the CNTs and improved the removal efficiency of HA by the buckypaper. The buckypaper prepared from purified CNTs exhibited excellent removal of HA (>93%) and a long lifetime for filtration. [Copyright &y& Elsevier]

Abstract: We first design and synthesize a MWNT/C/Mg1.03Mn0.97SiO4 hierarchical nanostructure composed of MWNTs pinning the surface of the Mg1.03Mn0.97SiO4 nanoparticles, with simultaneous tethering to Mg1.03Mn0.97SiO4 particles via an interfacial amorphous carbon phase bonding, through a facile CVD method. It is further demonstrated that the nanocomposite exhibits a reversible capacity as high as 300mAhg−1 at 0.2C and a stable cycling performance at 0.5C when utilized as a cathode material for rechargeable magnesium batteries. [Copyright &y& Elsevier]

A facile synthesis of three-dimensional (3D) network of copper confined nitrogen-doped graphene (NG)/carbon nanotube (CNT) with high atomic percentage of nitrogen (10.1 at.%) has been reported. The homogenous intercalation of the CNT network in-between the graphene layers decorated with copper nanoparticles take place which inhibits the self-agglomeration within the lattice and enhance the volumetric storage capability. The composite electrode demonstrates exceptionally high specific capacitance of 1250 mA h/g obtained at a current density of 0.1 A/g which is 3.4 times greater than the theoretical capacity of graphite (372 mA h/g). The discharge-charge profiles (from 0.002 to 3 V) with reversible battery capacity exhibit a stable state of the lithium-ion batteries which were observed at high rate capability of 420 mA h/g at a current density of 1 A/g even after 500 cycles. The enhancement of the electrochemical performance could be attributed to the 3D electrically conductive networks of copper confined nitrogen-doped graphene/carbon nanotubes (Cu@ N -Gr/CNT]). • 3-dimensional nanostructured copper confined nitrogen-doped graphene/carbon nanotube. • Contains high nitrogen content of 10.1 atomic wt.%. • Investigated as anode for lithium ion battery. • Specific capacitance of 1250 mA h/g at a current density of 0.1 A/g. • High rate capacitance of 420 mA h/g at a current density of 1 A/g after 500 cycles. [ABSTRACT FROM AUTHOR]