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Owing to the intrinsic excellent mechanical, electrical, and thermal properties of carbon nanotubes (CNTs), carbon nanotube fibers (CNTFs) have been expected to become promising candidates for the next-generation of high-performance fibers. They have received considerable interest for cutting-edge applications, such as ultra-light electric wire, aerospace craft, military equipment, and space elevators. Wet-spinning is a broadly utilized commercial technique for high-performance fiber manufacturing. Thus, compared with array spinning from drawable CNTs vertical array and direct dry spinning from floating catalyst chemical vapor deposition (FCCVD), the wet-spinning technique is considered to be a promising strategy to realize the production of CNTFs on a large scale. In this tutorial review, we begin with a summative description of CNTFs wet-spinning process. Then, we discuss the high-concentration CNTs wet-spinning dope preparation strategies and corresponding non-covalent adsorption/charge transfer mechanisms. The filament solidification during the coagulation process is another critical procedure for determining the configurations and properties for derived CNTFs. Next, we discuss post-treatment, including continuous drafting and thermal annealing, to further optimize the CNTs orientation and compact configuration. Finally, we summarize the physical property-structure relationship to give insights for further performance promotion in order to satisfy the prerequisite for detailed application. Insights into propelling high-performance CNTFs production from lab-scale to industry-scale are proposed, in anticipation of this novel fiber having an impact on our lives in the near future. [ABSTRACT FROM AUTHOR]

Hydrophobic carbon nanotubes are hardly to disperse in water and prone to agglomerate when poured with Copper Tailing-Based Cementitious Material (CTCM). Multi-walled carbon nanotubes (MWCNTs) + Arabic Gum (GA) dispersions were prepared by a novel method of synergistic optimization of concentration, controlling low-frequency ultrasonic time and setting the ambient temperature with non-toxic anionic surfactant GA as surfactant. The results of UV–Vis spectroscopy showed that the high stability MWCNTs + GA dispersion with low aggregation area (< 1.2%) and low aggregation beam size (< 219 nm) have been prepared by using 1.7 mmol/l GA. The effects of highly stable MWCNTs dispersion on the mechanical properties, microstructure and durability of CTCM were studied. The 28 days compressive strength increased by 21.5%, and the flexural strength increased by 20.5%, almost reaching the mechanical level of the control group. The results of SEM, XRD and EDS showed that GA significantly enhanced the dispersion of MWCNT in aqueous solution at a suitable concentration (mass ratio of GA:CNTs = 1:1). The microstructure of the prepared CTCM by high stability MWCNTs dispersion was optimized obviously, and the mechanical properties and durability were improved significantly. This method solves the dual problem of MWCNTs not being fully dispersed in aqueous solution and being easily re-agglomerated in cementitious materials, as well as finding a breakthrough for the low cost and industrialization of tailings cement-based composite cementitious materials. [ABSTRACT FROM AUTHOR]

Highly defective carbon nanotubes (HD-CNTs) are fabricated by template carbonization of polydopamine nanofilm coated on mesoporous titanium nitride nanotube arrays. With introduction of mesoporous holes on the side walls from the template, HD-CNTs exhibit much improved electrochemical properties. An ideal Nernst behavior toward [Fe(CN)6]3−/4− redox couple was observed on the HD-CNTs, with a heterogeneous charge transfer rate constant k0 greater than 0.5 cm/s that is among the fastest kinetics of electrode materials. Sensitive determination of dopamine has been demonstrated in the presence of ascorbic acid and uric acid, with a linear range of 0.1–180 μM, a detection limit of 0.074 μM (S/N = 3) and a sensitivity of 555 µA mM−1 cm−2. The excellent electrochemical activity should be attributed to the large number of exposed edge planes on the carbon nanofilm, the free-standing highly conductive titanium nitride architecture that is beneficial for electron transfer, mesoporous morphology that promotes the mass transfer between the nanotubes, and effective ion-accessible surface area. [ABSTRACT FROM AUTHOR]

Selecting a suitable catalyst for implementing the simultaneous production of hydrogen-rich syngas and multi-walled carbon nanotubes through the integration of dry reforming and methane decomposition reactions has recently gained great interests. In this study, a series of bimetallic (NiMo/MgO) and trimetallic (CoNiMo/MgO, FeNiMo/MgO, CoFeMo/MgO) catalysts was prepared and evaluated for a catalytic activity of CH4 and CO2 conversions of biogas in a fixed bed reactor at 800 °C and atmospheric pressure. Among the investigated catalysts, the bimetallic NiMo/MgO catalyst showed the outstanding catalytic performance with 86.4% CH4 conversion and 95.6% CO2 conversion as well as producing the highest syngas purity of 90.0% with H2/CO ratio = 1.1. Moreover, the characterization of the synthesized solid products proved that the well-aligned structured morphology, high purity, and excellent textural properties of CNTs were obtained by using NiMo/MgO catalyst. On the other hand, using trimetallic catalysts which have the composition of Co and Fe leads to the severe deactivation. This could be attributed the catalyst oxidation with CO2 in biogas, resulting in the transformation of metals into large metal oxides. The integrative process with NiMo/MgO catalyst is regarded as a promising pathway, which has a high potential for directly converting biogas into the high value-added products and providing a green approach for managing the enormous amounts of wastes. [ABSTRACT FROM AUTHOR]

Summary: This work is aimed to synthesize hybrid nanocomposite electrode materials for supercapacitor applications. The carbon nanotubes (CNTs) are incorporated into MoS2 as well as TiO2 to form different hybrid electrode materials such as MoS2/CNTs, TiO2/CNTs, and MoS2/TiO2/CNTs in an effort to improve the electrochemical performance. The resulting hybrid electrode materials are examined by SEM, TEM, XRD, XPS, and Raman studies. Cyclic voltammetry and galvanostatic charge‐discharge tests are used to evaluate the specific capacitance and charge‐discharge stability of the synthesized MoS2/TiO2/CNTs. Among the hybrid electrode materials investigated, the MoS2/TiO2/CNTs exhibits superior electrochemical performance with specific capacitance of 1252.57 mA h/g at a scan rate 20 mV/s as compared with MoS2/CNTs (810.53 mA h/g), TiO2/CNTs (607.10 mA h/g), and CNTs (204.35 mA h/g). All electrochemical tests were carried out in a solution of 1 M KOH. The Rct and Rf for the MoS2/TiO2/CNTs electrode were found to be 1.7 Ω.cm2 and 2.1 Ω.cm2, respectively, which were significantly lower than the corresponding Rct (40.2 Ω.cm2) and Rf (51.1 Ω.cm2) for the CNTs electrode, indicating that the MoS2/TiO2/CNTs has a significantly lower overall impedance, which could be one of the key factors responsible for the improved electrochemical performance of the MoS2/TiO2/CNTs. Moreover, this MoS2/TiO2/CNTs hybrid electrode displays good cycling stability with the capacitance retention of 98.83% after 10 000 cycles of charge‐discharge at 1 A/g. The energy density and power density of MoS2/TiO2/CNTs composites are found to be 757.80 Wh/kg and 4546.80 W/kg respectively. [ABSTRACT FROM AUTHOR]

Nitrogen doping of carbon nanomaterials has emerged as a method to develop novel material properties, though limitations in the form of extended treatment times, harsh chemical usage and limited total nitrogen content exist. Here, macroscopic ribbon-like assemblies of carbon nanotubes are functionalized with nitrogen using a simple direct current-based plasma–liquid system. This system utilizes the plasma-generated species in an ethanol:water solution with ethylenediamine as a nitrogen precursor for the nitrogen functionalization of the carbon nanotube assembly. These unique, plasma-generated species and pathways enable rapid and high levels of functionalization with the atomic concentration of nitrogen reaching 22.5%, with amine groups, pyrrolic groups and graphitic nitrogen observed in the X-ray photoelectron spectra, the highest ever achieved. This nitrogen content is demonstrated to be significantly higher than a comparative electrolysis process. This demonstrates that this plasma process enhances the availability of nitrogen from the ethylenediamine precursor, facilitating greater functionalization. [ABSTRACT FROM AUTHOR]

Relative humidity (RH) sensors have been fabricated with polyaniline-encased multiwall carbon nanotube (MWCNT) matrix. MWCNT matrices were grown on oxidized Si substrates by catalytic chemical vapour deposition technique. The MWCNT matrices were made hydrophilic by acid treatment. The sensing properties of MWCNTs were improved by encasing the acid-treated MWCNT matrix with PANI. PANI was synthesized via in situ chemical oxidation technique using three acid dopants, named as 5-sulfosalicylic acid, 4-nitrobenzoic acid and hydrochloric acid (HCl). A growth time variation of the PANI was also performed from 1.5 to 2.5 h. The time-varying sensor resistance was recorded with RH change, and RH sensing properties of the corresponding sensors were investigated with the measured data. Doping variation exhibited that CNT–PANI sensor, fabricated with HCl dopant, showed the highest response (42.6% at 90% RH). Synthesis time variation of PANI from 1.5 to 2.5 h exhibited that with an increase in synthesis time, the sensor responsivities degraded from 42.6 to 19.5% at 90% RH. Excellent repeatability, linear response behaviour (R2 = 0.992), low hysteresis loss (± 2.68%) were exhibited by the fabricated RH sensing devices. A facile transfer technology was developed in order to transfer the MWCNT on PET substrate for fabrication of flexible RH sensor. A practical application on human respiration monitoring was demonstrated with the wearable and flexible RH sensors. The humidity sensing mechanism and electron transfer process were schematically explained with the aid of energy band diagram. [ABSTRACT FROM AUTHOR]

A polymer–carbon hybrid nanocomposite based on thermostable electroactive poly-3-amine-7-methylamine-2-methylphenazine (PAMMP) and single-walled carbon nanotubes (SWCNT) was synthesized for the first time via in situ oxidative polymerization. The SWCNT/PAMMP nanocomposite material was characterized by means of Fourier transform infrared spectroscopy, solid-state high-resolution magic angle spinning 13C NMR spectroscopy, X-ray diffraction, transmission and field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis. The chemical structure of the synthesized SWCNT/PAMMP nanocomposite, as well as its thermal and electrical properties under different synthesis conditions, was studied. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the transition metals adsorption effect on the conductivity, density of states and carrier density of carbon nanotubes. We find that the electronic properties of CNTs are modulated in the presence of transition metal molecules. Both quasi-metallic and semiconductor behavior in the presence of Ag and Ti molecules are observed, respectively. The model is developed from tight-binding method, first-principles simulations are based on the density functional theory and non-equilibrium Green’s function method. The results of both approaches are in good agreement with each other. Our study reports the high sensitivity of CNTs to transition metal molecules and suggests that their adsorption on CNTs play significant role in modifying electronic behavior and conductivity of CNTs, so improves their potential for spintronics and sensing applications. [ABSTRACT FROM AUTHOR]

The effect of sodium dodecyl sulfate and carbon particles/nanotubes on the electropolymerization of aniline from oxalic acid solution onto a graphite electrode was investigated. The morphology and chemical structure of the as-synthesized polyaniline films were studied by means of SEM, XPS, NEXAFS, FTIR, and Raman spectroscopy. The electrochemical characteristics of the films were also analyzed in sulfuric acid solution. It has been shown that in the presence of sodium dodecyl sulfate, the polymerization rate increases significantly. In the synthesized polyaniline films, all imine groups and most of amine groups are protonated, with dodecyl sulfate ions being intercalated in the polymer. In the presence of sodium dodecyl sulfate, plate-like polyaniline forms large agglomerates with an extended surface and high electrochemical activity. It has been shown that the electrodeposition carried out in the presence of sodium dodecyl sulfate and suspended activated graphite particles or carbon nanotubes favors the formation of composite coatings with high specific capacitance. [ABSTRACT FROM AUTHOR]

Carbon has long been applied as an electrochemical sensing interface owing to its unique electrochemical properties. Moreover, recent advances in material design and synthesis, particularly nanomaterials, has produced robust electrochemical sensing systems that display superior analytical performance. Carbon nanotubes (CNTs) are one of the most extensively studied nanostructures because of their unique properties. In terms of electroanalysis, the ability of CNTs to augment the electrochemical reactivity of important biomolecules and promote electron transfer reactions of proteins is of particular interest. The remarkable sensitivity of CNTs to changes in surface conductivity due to the presence of adsorbates permits their application as highly sensitive nanoscale sensors. CNT-modified electrodes have also demonstrated their utility as anchors for biomolecules such as nucleic acids, and their ability to diminish surface fouling effects. Consequently, CNTs are highly attractive to researchers as a basis for many electrochemical sensors. Similarly, synthetic diamonds electrochemical properties, such as superior chemical inertness and biocompatibility, make it desirable both for (bio) chemical sensing and as the electrochemical interface for biological systems. This is highlighted by the recent development of multiple electrochemical diamond-based biosensors and bio interfaces. [ABSTRACT FROM AUTHOR]

One of the most suitable approaches for the production of inorganic nanotubes is by means of carbon nanotube (CNT) templates coated by atomic layer deposition (ALD). This approach is attractive because it has the potential of controlling the wall thickness down to the Angstroms level. However, it is a recognized fact that the chemistry of the substrate surface can delay the full coverage at the initial stages of the ALD coating process, mainly due to nucleation issues. This is an important issue that might restrict laying down homogeneous coatings within the ultrathin range, which is the foundation for producing self-supported inorganic nanotubes. Here, we explore the early stage of the TiO nucleation on CNT templates systematically functionalized with different chemical groups (COOH, OH) or N-doped. The effects of the functionalization on the nucleation process from tetrakis (dimethylamino) titanium and water were meticulously studied by means of transmission electron microscopy. Observations revealed grain-like growth of TiO over pristine, purified and -OH-functionalized CNTs. In contrast, COOH functionalization yielded good conformality, which was improved on N-doped CNTs. Results were confirmed by X-rays photoelectron spectroscopy analysis. We recommend either COOH or N-doped CNTs for the production of ultrathin TiO nanotubes. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (N-CNTs) containing different nitrogen species were synthesized via a chemical vapour deposition technique. This was archived by use of ferrocene and ferrocenyl-2-(4-cyanophenyl)acrylonitrile as catalysts. The N-CNTs were acid-treated and then used as Pd nanoparticle supports (Pd/N-CNTs). Both N-CNTs and Pd/N-CNTs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and other spectroscopic techniques. The selective reduction of nitroarenes to anilines was used as a model reaction to test the effect of pyridinic- and pyrrolic-nitrogen species on the catalytic performance of Pd/N-CNTs. A larger number of pyridinic-nitrogens in the N-CNTs increased nitroarene conversion and enhanced the selectivity towards anilines as opposed to the pyrrolic-nitrogens. Also, pyridinic-nitrogens favoured the nucleation of Pd nanoparticles with higher surface areas than those nucleated in the presence of pyrrolic-nitrogens. Density functional theory calculations were employed to determine the band-gap energy and optimal geometry of Pd complexed to pyridine and pyrrole ligands. These results showed that the pyridine complex had a lower band-gap energy (5.804 eV) than the pyrrole complex (6.406 eV) implying that the former complex is more reactive than the later. Thus, the inclusion of pyridinic-nitrogens in the N-CNTs, used as support, favours Pd-catalyzed nitroarene reductions. [ABSTRACT FROM AUTHOR]

Since the 1970s, palladium-catalysed carbon-carbon (C-C) bond formation has made a critical impact in organic synthesis. In early studies, homogeneous palladium catalysts were extensively used for this reaction with limitations such as difficulty in separation and recycling ability. Lately, heterogeneous palladium-based catalysts have shown promise as surrogates for conventional homogeneous catalysts in C-C coupling reactions, since the product is easy to isolate, while the catalyst is reusable and hence sustainable. Recently, a better part of these heterogeneous palladium catalysts are supported on carbon nanotubes (Pd/CNTs), that have shown superior catalytic performance and better recyclability since the CNT support imparts stability to the palladium catalyst. This review discusses the wide variety of surface functionalization techniques for CNTs that improve their properties as catalyst supports, as well as the methods available for loading the catalyst nanoparticles onto the CNTs. It will survey the literature where Pd/CNTs catalysts have been utilized for C-C coupling reactions, with particular emphasis on Suzuki-Miyaura and Mizoroki-Heck coupling reactions. It will also highlight some of the important parameters that affect these reactions. [ABSTRACT FROM AUTHOR]

The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field. Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler. [ABSTRACT FROM AUTHOR]

In this work we present an ab initio study of electronic properties of one-dimensional (1D) core-shell nanostructures made of MS (MoS, WS) or BN armchair nanotube encapsulated carbon nanotubes (CNT). With local density approximation in density functional theory we calculate the band structure, carrier effective masses, various fundamental electrostatic features and optical absorption in such core-shell tubes. The carrier transport in these structures is important for nanoelectronics applications and is studied with the Green's function formalism. Simulations show a moderate indirect band gap in the core-shell CNT@MS tubes, while the CNT@BN shows metallic nature. The varying chirality of CNT strongly affects the carrier effective masses of the CNT@MS structure. Electron density is found to be much more localized near the atom cores and stronger in magnitude for the CNT@BN, while the W atoms show a more prominent electron-gas presence around them than Mo atoms as found in the electron localization functions. In the CNT@MS systems, the electrostatic difference potential indicates a drive to transfer charge from the metal to the S atoms in the shell. In terms of optical absorption, a strong and sharper peak is observed around 6 eV for the CNT@BN compared to a more broad absorption spectra of the CNT@MS. Metallic transmission spectra are seen for CNT@BN, while CNT@MS shows non-metallic transport but with a larger number of transmission states near Fermi level. The electronic and optical properties and its possible tuning in the core-shell structures can be useful in various applications such as shielded interconnects, logic switches and optoelectronics. [ABSTRACT FROM AUTHOR]

The advancement of modern electronic devices depends strongly on the highly efficient energy sources possessing high energy density and power density. In this regard, supercapacitors show great promise. Due to the unique hierarchical structure, excellent electrical and mechanical properties, and high specific surface area, carbon nanomaterials (particularly, carbon nanotubes, graphene, mesoporous carbon and their hybrids) have been widely investigated as efficient electrodematerials in supercapacitors.This review article summarizes progress in high-performance supercapacitors based on carbon nanomaterials with an emphasis on the design and fabrication of electrode structures and elucidation of charge-storage mechanisms. Recent developments on carbon-based flexible and stretchable supercapacitors for various potential applications, including integrated energy sources, self-powered sensors and wearable electronics, are also discussed. [ABSTRACT FROM AUTHOR]

The electric and magnetic field distributions as well as the dispersion characteristics of open cylindrical tube (hollow-core) waveguides are analysed in this work. The analysed waveguides are made of an onion-like carbon (OLC) material. The solution of the boundary problem was fulfilled by the partial area method. It was discovered the very complicated dependencies of the phase and attenuation constants on the waveguide radii. Such dependencies arise because the OLC material is the highly dispersive and absorbing one. The fundamental and four higher modes can propagate in our investigated waveguides. We have analysed the high-frequency cut-off frequency of modes that is dependent on the tube waveguide external radius. The certain electromagnetic (EM) mode can propagate only on the frequencies lower than the mentioned cut-off frequency. For this reason, this cut-off frequency has an important use in practical applications. We presented here the EM field distributions of modes. We discovered that it is possible to reach the one-mode regime of OLC tube waveguide at the certain external radius. The fundamental and first higher modes’ EM energy is concentrated in the OLC material between the internal and external surfaces of the waveguide. [ABSTRACT FROM AUTHOR]

In this study, we present a novel anode architecture for high-performance lithium-ion batteries based on a Silicon/3-aminosilane-functionalized CNT/Carbon (Si/A-CNT/C) composite. A high-yield, low-cost approach has been developed to stabilize and support silicon as an active anode material. Silicon (Si) nanoparticles synthesized in a hot-wall reactor and aminosilane-functionalized carbon nanotubes (A-CNT) were dispersed in styrene and divinylbenzene (DVB) and subsequently polymerized forming a porous Si/A-CNT/C composite. Transmission electron microscopy showed that this method enables the interconnection and a uniform encapsulation of Si nanoparticles within a porous carbon matrix especially using aminosilane-functionalized CNT (A-CNT). Electrochemical characterization shows that this material can deliver a delithiation capacity of 2293 mAh g with a capacity retention of more than 90 % after 200 cycles at lithiation and delithiation rate of 0.5 C. We conclude that the porous Si/A-CNT/C composite material can accommodate sufficient space for Si volume expansion and extraction and improve the electronic and ionic conduction. Excellent electrochemical performance during repeated cycling can thus be achieved. [ABSTRACT FROM AUTHOR]

A free-standing sulfur/nitrogen-doped carbon nanotube (S/N-CNT) composite prepared via a simple solution method was first studied as a cathode material for lithium/sulfur batteries. By taking advantage of the self-weaving behavior of N-CNT, binders and current collectors are rendered unnecessary in the cathode, thereby simplifying its manufacturing and increasing the sulfur weight ratio in the electrode. Transmission electronic microscopy showed the formation of a highly developed core-shell tubular structure consisting of S/N-CNT composite with uniform sulfur coating on the surface of N-CNT. As a core in the composite, the N-CNT with N functionalization provides a highly conductive and mechanically flexible framework, enhancing the electronic conductivity and consequently the rate capability of the material. [ABSTRACT FROM AUTHOR]

In the last four to five years, there has been a great resurgence of research on two-dimensional inorganic materials, partly because of the impetus received from graphene research. Unlike graphene, which is a gap-less material, most inorganic layered materials are semiconductors or insulators. Some of them, as exemplified by MoS2, exhibit unexpected properties, not unlike graphene, with possible applications. Thus, layered metal chalcogenides are being explored intensely, and MoS2 is emerging as a wonder material. In this article, we present the synthesis and properties of nanosheets composing single or few layers of these fascinating materials. Besides metal chalcogenides, boron nitride, borocarbonitrides (B xC yN z), metal oxides, and metal-organic frameworks are also discussed. [ABSTRACT FROM AUTHOR]

Present work deals with the pseudocapacitance of carbon nanomaterials modified by nitrogen heterosubstitution and electroactive polymers taking place in ionic liquids and lithium salts solutions in organic media. It is shown that N-doped materials, where nitrogen atoms are located within grahene layers, due to excess of electrons and variation of specific cooperation demonstrates higher capacitance than non-doped samples in the whole range of voltage applied, restricted by electrochemical stability window of electrolyte. The values were found to mostly depend on correlations of the ions size and pore size in the material. For composites of carbon nanotubes with electroactive polypyrrole, obtained electrochemically in the ionic liquid, the capacitance can increase more than 3 times due to reversible red-ox processes. In case of high purity of components there were no polymer degradation process observed. The possibility of implementation of mixed electrolytes based on solutions of high voltage ionic liquids with symmetrical electrochemical stability window and lithium salts in dry acetonitrile for realization of pseudocapacitance effect together with ion-pore� size correlations is proposed. [ABSTRACT FROM AUTHOR]

Electric double layer capacitors, also called supercapacitors, ultracapacitors, and electrochemical capacitors, are gaining increasing popularity in high power energy storage applications. Novel carbon materials with high surface area, high electrical conductivity, as well as a range of shapes, sizes and pore size distributions are being constantly developed and tested as potential supercapacitor electrodes. This article provides an overview of the electrochemical studies on activated carbon, carbide derived carbon, zeolite-templated carbon, carbon aerogel, carbon nanotube, onion-like carbon, and graphene. We discuss the key performance advantages and limitations of various nanostructured carbon materials and provide an overview of the current understanding of the structure-property relationships related to the transport and adsorption of electrolyte ions on their surfaces, specific and volumetric capacitance, self-discharge, cycle life, electrolyte stability, and others. We discuss the impact of microstructural defects, pore size distribution, pore tortuosity, chemistry and functional groups on the carbon surface, nanoscale curvature, and carbon-electrolyte interfacial energy. Finally, we review state-of-the art commercial large scale applications of supercapacitors, including their use in smart grids and distributed energy storage, hybrid electric and electric vehicles, energy efficient industrial equipment, ships, wind power stations, uninterruptible power supplies, power backup, and consumer devices. WIREs Energy Environ 2014, 3:424-473. doi: 10.1002/wene.102 For further resources related to this article, please visit the . Conflict of interest: The authors have declared no conflicts of interest for this article. [ABSTRACT FROM AUTHOR]

Stacked-cup type multiwall carbon nanotubes (MWCNTs) were synthesized by floating catalyst chemical vapor deposition methods. The materials were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements showed that the stacked-cup-type MWCNTs as lithium-ion battery anode materials delivered a stable capacity of ~310 mAh g at a rate of C/2 to 300 cycles. Furthermore, the materials were very stable and the coulombic efficiency exceeded 99.9 % over more than 300 cycles. Stable materials structure and the solid electrolyte interphase films were the main reasons for the durable cycling behavior, as confirmed by ex situ TEM and Raman spectroscopy, as well as electrochemical impedance spectroscopy (EIS). The results indicated that the stacked-cup-type MWCNTs produced in this work are candidate materials for lithium-ion battery anodes. [ABSTRACT FROM AUTHOR]

We investigated the local order in individual iron nanoparticles (NPs) embedded in carbon nanotubes (CNTs). The NPs directly come from the CNT growth on stainless steel without addition of external metal catalyst. The structural analysis has been obtained through nanoscale transmission extended electron energy loss fine structure (EXELFS) measurements above the iron L edge. A theoretical simulation of the EXELFS features has been performed within the multiple scattering theory. By comparing the experimental data with the simulations, we found that pure γ-Fe and FeC nanoparticles are the catalysts of the CNT synthesis on the stainless steel. Moreover, from the analysis of the fine details of the EXELFS oscillations, we also estimated the value of the fcc Fe NP lattice parameter to be a = 3.61 ± 0.03 Å. This last finding suggests a high magnetic moment of the fcc Fe NPs. [ABSTRACT FROM AUTHOR]

Microporous carbons are important in a wide variety of applications, ranging from pollution control to supercapacitors, yet their structure at the molecular level is poorly understood. Over the years, many structural models have been put forward, but none has been entirely satisfactory in explaining the properties of the carbons. The discovery of fullerenes and fullerene-related structures such as carbon nanotubes gave us a new perspective on the structure of solid carbon, and in 1997 it was suggested that microporous carbon may have a structure related to that of the fullerenes. Recently, evidence in support of such a structure has been obtained using aberration-corrected transmission electron microscopy, electron energy loss spectroscopy and other techniques. This article describes the development of ideas about the structure of microporous carbon, and reviews the experimental evidence for a fullerene-related structure. Theoretical models of the structural evolution of microporous carbon are summarised, and the use of fullerene-like models to predict the adsorptive properties of microporous carbons are reviewed. [ABSTRACT FROM AUTHOR]

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) were synthesized by means of catalytic chemical vapor deposition technique using acetonitrile as carbon source material and ferrocene as catalyst. The structure of the synthesized N-MWCNT was characterized by means of microscopic (SEM, HRTEM) as well as spectroscopic (FTIR, Raman) techniques. Furthermore, the specific resistivity and the electrochemical properties of N-MWCNT were investigated and compared with those of pristine MWCNT. The results are discussed in terms of structural differences between pristine MWCNT and N-MWCNT. [ABSTRACT FROM AUTHOR]

Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) have been prepared by pyrolysis of pyridine and iron phthalocyanine over an iron catalyst at 850 °C at various ammonia gas (NH) flow rates. X-ray photoelectron spectroscopy results reveal that the pyridine-like nitrogen (N) content can be controlled by changing the flow rate of NH, and that pyridine-like N plays an important role: it can increase the electrocatalytic activity and the rate of nitric oxide (NO) electrooxidation and decrease the activation energy of NO electrooxidation. Cyclic voltammetry results demonstrate that the N-MWCNTs sample grown with 200 mL/min NH flow has the maximum N content of 3.22 atomic %, and its content of pyridine-like N that is chemically active is also the highest among all the N-MWCNTs samples. Electrochemical impedance spectroscopy results indicate that two-step electron transfer process occurs at the N-MWCNT-modified electrode, and the control step is different in various potential regions. The stability of NO electrooxidation at the N-MWCNT-modified electrode is examined, and the reaction mechanism is discussed. [ABSTRACT FROM AUTHOR]

Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) were synthesized by thermal decomposition of pyridine and iron phthalocyanine over an iron catalyst in an atmosphere of ammonia. The N-MWCNTs thus obtained were analyzed by X-ray photoelectron spectroscopy. They were found to contain three types of nitrogen (N) atoms, namely pyridine-like, graphite-like, and molecular N. The effect of the pyridine-like N and the graphite-like N was investigated. The pyridine-like N is absorbing nitric oxide (NO) more easily than the graphite-like N. The N-MWCNTs with higher N content (especially the pyridine-like N) have higher catalytic activity (in terms of electrooxidation of NO) than those containing less N. The N-MWCNTs with high levels of pyridine N were incorporated into an electrode which suitable for sensing NO and for removal of NO due to its excellent electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract  Metal-carbon nanotube-graft-polymer (MCNT-g-P) nanocomposites were synthesized and characterized successfully. In this work, multiwall carbon nanotubes (MWCNT) were opened using HNO3/H2SO4 mixture and filled by metal nanoparticles such as silver nanoparticles through wet chemistry method. Then MWCNT containing metal nanoparticles were used as macroinitiator for ring opening polymerization of ε-caprolactone and MCNT-g-P nanocomposites were obtained. Length of grafted polymer arms onto the MWCNT was controlled using MWCNT/ε-caprolactone ratio. Structure and properties of nanocomposites were evaluated by TEM, DSC, TGA, and spectroscopy methods. [ABSTRACT FROM AUTHOR]