Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT–ZnO Heterostructures

In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs) is achieved using atomic layer deposition (ALD). Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL) measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT–inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials.     

Platinum–Vanadium Oxide Nanotube Hybrids

The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H₂PtCl₆ is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm.     

Promotion Effects of Platinum and Ruthenium on Carbon Nanotube Supported Cobalt Catalysts for Fischer–Tropsch Synthesis

Abstract  

Carbon nanotube supported nano-size monometallic and noble metal (Pt and Ru) promoted cobalt catalysts were prepared by incipient wetness impregnation (IWI) using solution of cobalt nitrate and characterized by nitrogen adsorption isotherm, X-ray diffraction (XRD), temperature programmed reduction, in situ magnetic method and TEM. Analysis of the magnetization and H₂-TPR data suggested promotion with platinum and ruthenium significantly decreased the cobalt species reduction temperature. TEM and XRD results showed that the presence of noble metal promoters had no significant effect on the size of cobalt for carbon naotube as catalytic support. Promotion of cobalt carbon nanotube-supported catalysts with small amounts of Pt and Ru resulted in slight increase in Fischer–Tropsch cobalt time yield. The Pt and Ru promoted cobalt catalyst exhibited carbon monoxide conversion of 37.1 and 31.4, respectively. C₅+ hydrocarbon selectivity was attained at 80.0%. The Pt promoted cobalt supported on carbon nanotube yielded better catalytic stability than that of the monometallic cobalt catalyst.     

Exploitation of Nanobifiller in Polymer/Graphene Oxide–Carbon Nanotube,Polymer/Graphene Oxide–Nanodiamond,and Polymer/Graphene Oxide–Montmorillonite Composite: A Review

In this article, a comprehensive review is presented regarding structure, synthesis, and properties of nanofillers such as graphene oxide, nanobifiller of graphene oxide, and their polymeric nanocomposite. The information about hybrid properties and synthesis of graphene oxide–carbon nanotube, graphene oxide–montmorillonite, and graphene oxide–nanodiamond is presented. Use of nanobifiller in polymer/graphene oxide–carbon nanotube, polymer/graphene oxide–montmorillonite, and polymer/graphene oxide–nanodiamond composites was summarized. Area of polymer and graphene oxide-based nanobifiller composites is less studied in literature. Therefore, nanobifiller technology limitations and research challenges must be focused. Polymer/graphene oxide nanobifiller composites have a wide range of unexplored potential in technological areas such as automobile, aerospace, energy, and medical industries.     

Synthesis and Characterization of AgBr–Silk Nanocomposite Under Ultrasound Irradiation

The growth of silver bromide nanoparticles on silk yarn was achieved by sequential dipping in alternating bath of potassium bromide and silver nitrate under ultrasound irradiation. The effect of concentration, power of ultrasound irradiation and the numerous of sequential dipping steps in growth of the AgBr nanoparticles on silk yarn were studied. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Inductive Coupled Plasma (ICP). The lower average size and the higher crowded AgBr nanoparticles upon silk yarn are the result of using ultrasound irradiation.     

Synthesis and characterization of chlorapatite–ZnO composite nanopowders

The influence of zinc oxide content on the formation of chlorapatite-based composite nanopowders in the mechanically alloyed CaO–CaCl₂–P₂O₅–ZnO system was studied. To mechanosynthesize composite nanopowders, different amounts of hydrothermally synthesized zinc oxide nanoparticles (0–10 wt%) were mixed with ingredients and then were mechanically activated for 5 h. Results showed that in the absence of zinc oxide, high crystalline chlorapatite nanopowder was obtained after 5 h of milling. In the presence of 4 and 7 wt% zinc oxide, the main product of milling for 5 h was chlorapatite–zinc oxide composite nanopowder. On increasing the zinc oxide content to 10 wt%, composite nanopowder was not formed due to improper stoichiometric ratio of the reactants. The crystallite size, lattice strain, volume fraction of grain boundary, and crystallinity degree of the samples fluctuated significantly during the milling process. In the presence of 7 wt% zinc oxide, the crystallite size and crystallinity degree reached 51±2 nm and 79±2%, respectively. During annealing at 900 °C for 1 h, the crystallization of composite nanopowder occurred and as a result the crystallinity degree rose sharply to 96±3%. In addition, the crystallite size increased to 77±2 nm after annealing at 900 °C. According to SEM and TEM images, the composite nanopowder was composed of both ellipse-like and polygonal particles with a mean size of about 98 nm.     

Ultrasound Synthesis of Polyindole–TiO2 Nanocomposite and Evaluation of Antibacterial Activity

The present work reports the synthesis and evaluation of antimicrobial activity of polyindole–TiO₂ nanocomposite. Polyindole–TiO₂ nanocomposite was synthesized by aqueous in situ chemical polymerization of indole using ammonium persulfate as an oxidant under ultrasonic condition. The synthesized polyindole and polyindole–TiO₂ nanocomposites were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope, thermogravimetric analysis, and X-ray diffraction techniques. A sharp peak at ～1,402?cm^?1 is due to the stretching vibrations of O?Ti?O bond in polyindole–TiO₂ nanocomposite. The X-ray diffraction pattern shows the major diffraction peaks at 25°C and 48°C, indicating TiO₂ in anatase form. Polyindole–TiO₂ shows maximum activity against gram-positive Staphylococcus aureus and Bacillus subtilis as compared to gram-negative Escherichia coli.     

Characterisation and modelling of CNT–epoxy and CNT–fibre–epoxy composites

Abstract

This research presents an experimental and theoretical investigation on the effects of carbon nanotube (CNT) integration within neat epoxy resin (nanocomposites) and a carbon fabric–epoxy composite (multiscale composites). An approach is presented for the prediction of mechanical properties of multiscale composites. This approach combines woven fibre micromechanics (MESOTEX) with the Mori-Tanaka model which was used for the prediction of mechanical properties of nanocomposites in this research. Nanocomposite and multiscale composite samples were manufactured using cast moulding, resin infusion, and hand lay-up process. The CNT concentrations in the composite samples were from 0 to 5 wt-%. The samples were characterised using tensile, shear and flexural tests. The discrepancy between the theoretical predictions and the experimental observations was hypothesised to be due to dispersion and bonding issues and SEM images are presented in support of the hypothesis.     

Synthesis and Characterization of Mn–Ce–VOx/TiO2 Nanocomposite for SCR of NOx at Low Temperatures: Role of Mn,Ce and V Oxide

Topics in Catalysis - Mn–Ce–VOx/TiO2 (MnCeVTi), Mn–CeOx/TiO2 (MnCeTi) and Mn–VOx/TiO2 (MnVTi) nanocomposites as SCR DeNOx catalysts were synthesized by a modified...     

Electromagnetic Interference Shielding of Polymer/Nanodiamond,Polymer/Carbon Nanotube,and Polymer/Nanodiamond–Carbon Nanotube Nanobifiller Composite: A Review

In this review, properties and potential of carbon nanotube, nanodiamond, and nanodiamond–carbon nanotube hybrid nanobifiller have been discussed with reference to electromagnetic interference shielding materials. The nanodiamond and carbon nanotube nanofiller and nanodiamond–carbon nanotube nanobifiller have outstanding electrical, thermal, and mechanical features. Main focus of review was electromagnetic interference shielding phenomenon and its implication in polymer/nanodiamond, polymer/carbon nanotube, and polymer/nanodiamond–carbon nanotube nanobifiller composite. The epoxy/nanodiamond, epoxy/carbon nanotube, and epoxy/nanodiamond–carbon nanotube composites have been discussed with electromagnetic interference shielding shielding features. Thus, considerable enhancement in electromagnetic interference shielding shielding features was observed using higher nanodiamond, carbon nanotube, and nanodiamond–carbon nanotube loadings. Significance and future potential of these polymeric composite are specified.     

Synthesis and Self-assembling Properties of 2,2′:6′,2″-Terpyridine-Based Carbon Nanotube Coordination Polymers

A novel metallo-supramolecular polytopic ligand was synthesized from the attachment reaction involving an amino group-functionalized multi-wall carbon nanotube and 4-chloro-2,2′:6′,2″-terpyridine used for the preparation of metallo-supramolecular polymers with Co(II) or Ni(II) ions. Different colors were observed depending on either the ligands or the metal ions in this type of supramolecular assembly. The created supramolecular polymers were characterized by means of structure, morphology, and stimuli-responsive performance employing scanning electron microscopy, amperometric techniques, UV–Vis and Fourier transform infrared spectroscopy. UV–Vis spectroscopy and cyclic voltammetry studies confirmed that both the optical and electrochemical properties of metallo-supramolecular materials are affected by the substituent at the pyridine periphery.     

Microcalorimetric Investigation of the Interaction of Carbon Monoxide with Coprecipitated Cupric Oxide—Zinc Oxide Catalysts in Well-Defined Oxidation States

Carbon monoxide is readily adsorbed onto copper—zinc systems of different copper content. The adsorptive capacity, the heat and the kinetics of the interaction depend upon the oxidation state of the sample. The prevailing interaction on fully reduced samples is adsorption of carbon monoxide on copper metal, whereas in the case of partially oxidized samples and in that of cupric oxide—zinc oxide obtained by calcination of the precursor, redox reactions occur involving reduction of the surface, in parallel with the coordination of carbon monoxide on copper centres in various oxidation states. The heat of coordination of carbon monoxide onto copper (O) and copper (I) centres is in the range 66–43 kJ/mol and 110–66 kJ/mol respectively. The assignments have been made on the basis of the correspondence between carbonyl IR frequencies and heat of adsorption. Quantitative data on adsorption are also discussed in terms of the effect of the dispersion of the active phase and the role of the zinc oxide matrix.     

Polymer-Salt Synthesis of Photoactive Bactericide ZnO–Ag and ZnO–SnO2–Ag Nanopowders and a Study of Their Structure and Properties

Glass Physics and Chemistry - This paper describes the low-temperature polymer-salt synthesis of ZnO–Ag nanopowders and presents the results of studying their structure, morphology, and...     

Thermal Properties of Carbon Nanotube–Copper Composites for Thermal Management Applications

Carbon nanotube–copper (CNT/Cu) composites have been successfully synthesized by means of a novel particles-compositing process followed by spark plasma sintering (SPS) technique. The thermal conductivity of the composites was measured by a laser flash technique and theoretical analyzed using an effective medium approach. The experimental results showed that the thermal conductivity unusually decreased after the incorporation of CNTs. Theoretical analyses revealed that the interfacial thermal resistance between the CNTs and the Cu matrix plays a crucial role in determining the thermal conductivity of bulk composites, and only small interfacial thermal resistance can induce a significant degradation in thermal conductivity for CNT/Cu composites. The influence of sintering condition on the thermal conductivity depended on the combined effects of multiple factors, i.e. porosity, CNTs distribution and CNT kinks or twists. The composites sintered at 600°C for 5 min under 50 MPa showed the maximum thermal conductivity. CNT/Cu composites are considered to be a promising material for thermal management applications.     

Time–Temperature-Transformation Cure Diagram of Multiwall Carbon Nanotube/Epoxy Composites

This work describes the effects of multiwall carbon nanotube on the isothermal time–temperature-transformation cure diagram to obtain a comprehensive cure map for a 2 wt% multiwall carbon nanotube/epoxy composite. The viscoelastic and thermal properties of the nanocomposites for a wide range of isothermal cure temperatures were obtained using a strain-controlled rheometer ARES TA and a differential scanning calorimetry. The thermal and rheological analyses were used to investigate the vitrification and the gelation of the nanocomposite, and to draw the time–temperature-transformation diagram. This diagram is completed by adding the iso-viscosity curves.     

Electroluminescent Characteristics of DBPPV–ZnO Nanocomposite Polymer Light Emitting Devices

We have demonstrated that fabrication and characterization of nanocomposite polymer light emitting devices with metal Zinc Oxide (ZnO) nanoparticles and 2,3-dibutoxy-1,4-poly(phenylenevinylene) (DBPPV). The current and luminance characteristics of devices with ZnO nanoparticles are much better than those of device with pure DBPPV. Optimized maximum luminance efficiencies of DBPPV–ZnO (3:1 wt%) before annealing (1.78 cd/A) and after annealing (2.45 cd/A) having a brightness 643 and 776 cd/m² at a current density of 36.16 and 31.67 mA/cm² are observed, respectively. Current density–voltage and brightness–voltage characteristics indicate that addition of ZnO nanoparticles can facilitate electrical injection and charge transport. The thermal annealing is thought to result in the formation of an interfacial layer between emissive polymer film and cathode.     

Polyaniline–Carbon Nanotube Composites: Preparation Methods,Properties, and Applications

Synthesis of polyaniline and hybrid carbon nanotube reinforced polyaniline nanocomposites by various methods has discussed in this review. Different routes used for functionalization of carbon nanotube have been reported. The electrical, mechanical, and thermal properties of polyaniline/carbon nanotube nanocomposites are also discussed. The dispersion of functionalized carbon nanotube, filler concentration, and their alignment in the interior of polyaniline matrix affect their morphology. Furthermore, article focussed upon the various morphologies of polyaniline and polyaniline/carbon nanotube nanocomposites obtained with different methods along with electrical conductivity. Possible applications of polyaniline/carbon nanotube nanocomposites in the areas of actuators, sensors, electromagnetic interference shielding have also discussed.     

Aptitude of Graphene Oxide–Silver in Advance Polymer Nanocomposite: A Review

This is a state-of-the art overview on polymer/graphene oxide–silver nanoparticle nanocomposite. Different polymer/graphene oxide–silver nanoparticle categories have been elucidated using polyethersulfone, polyimides, polyindole, poly(vinylidene fluoride), polyaniline, polyvinyl pyrrolidone, and poly(3,4-ethylenedioxythiophene). In situ reduction of silver salt and particle decoration on graphene oxide surface were effective to develop interaction between nanoparticles. Essential features of polymer/graphene oxide–silver nanoparticle revealed several advance technical applications. Conducting polymer/graphene oxide–silver nanoparticle is promising material for sensor, supercapacitor, and electrodes. Polymer/graphene oxide–silver nanoparticle possesses relevance in cancer treatment, gene transfection, cellular probing, imaging, antibacterial action, etc. Polyimide/graphene oxide–silver nanoparticle can also effectively prevent membrane bifouling. Catalytic activity of composites was also detected toward oxygen reduction in energy devices.