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Oxidized single walled carbon nanohorns (ox-SWCNH) were electrodeposited onto gold microelectrode arrays in conjunction with poly(3,4-ethylenedioxythiophene) (PEDOT) and polystirenesulfonate (PSS), and the properties of the new composite material for neural recording and stimulation were assessed. PEDOT/ox-SWCNH composites were compared with films prepared with one of the most notorious carbonaceous material in this field, the oxidized multi-walled Carbon Nanotubes (ox-MWCNT). The PEDOT/ox-SWCNH exhibited superior charge transfer capability, reflecting greater electroactive surface, as confirmed by SEM and EIS characterizations. As a consequence, a charge injection limit of 11.6mC/cm⁠2 was observed for the new composite, which is higher than the one of PEDOT/ox-MWCNT (8.7mC/cm⁠2). Having confirmed comparable neural recording performance, the PEDOT/ ox-SWCNH composite results very promising for improving therapeutic electrical stimulation in the central and peripheral nervous systems.

High-performance bilayer counter electrodes (BCEs) for dye-sensitized solar cell (DSSC) applications are gaining considerable attention. In this study, MoS2 /single-walled carbon nanohorn (SWCNHs) BCEs were fabricated by ultrasonic-spray-assisted electrochemical deposition. The BCEs exhibited superior electrocatalytic activity, confirmed through CV, Tafel plots, and electrochemical impedance spectroscopic studies. The fabricated MoS2 /SWCNH-based DSSCs exhibited an impressive photovoltaic power conversion efficiency of 9.48 %, which is higher than the performance of cells with Pt-containing CEs (8.64 %). The simple and reliable growth strategy for bilayer film CEs provides a new route for the preparation of cost-effective and high-performance catalytic BCEs for renewable energy applications involving Pt-free DSSCs.

We report for the first time the chromatographic study of n-alcohols (from methanol to butanol) adsorption on single walled carbon nanohorn (SWCNH). Using measured temperature dependence of adsorption isotherms (373–433 K) the isosteric adsorption enthalpy is calculated and compared with the data reported for a graphite surface. It is concluded that a graphite surface is more homogeneous, and the enthalpy of adsorption on SWCNHs at zero coverage correlates well with molecular diameter and polarizability, suggesting leading role of dispersive interactions, i.e., no heteroatoms presence in the walls of SWCNH structures. Next using modern DFT approach we calculate the energy of n-alcohols interactions with a graphene sheet and with a single nanocone finally proposing a more realistic—double nanocone model. Obtained results suggest alcohols entrapping between SWCNH with OH groups located toward nanocones ends, leading to the conclusions about very promising future applications of SWCNHs in catalytic reactions with participation of n-alcohols.

Recently, substantial focus has made in the development of cost effective Pt-free dye sensitized solar cells (DSSCs). In this article we report a potential, Pt-free, carbon based nanocomposite as counter electrode catalyst for dye sensitized solar cells. Graphene oxide (GO) was made into reduced graphene oxide (SSrGO) by irradiating with light (Xe source). Suspension of SSrGO in DMF was spray coated onto fluorine doped tin oxide (FTO) coated glass substrate, followed by spray coat of single walled carbon nanohorns (SWCNH) suspension in DMF. SSrGO and SWCNH coated FTO glass substrate was investigated as an effective Pt-free composite counter electrode (CE) for DSSC and also showed the comparable catalytic activity with Pt. The test cell reveals power conversion efficiency (PCE) of 8.27%, whereas the DSSC module exhibited a PCE of 5.18%. By using the fabricated DSSC module, an electric motor (15 mW) was operated both in indoor and outdoor light conditions. The procedures followed in this work pave a way for the easy fabrication of composite CE towards transparent DSSC modules and further the integration of the DSSC module with the standard Si solar cell is of great potential for various real-time application.

The low density of porous carbon nanomaterials for supercapacitor electrodes has limited their widespread application, despite their ultra-high gravimetric capacitance. In this work, we successfully prepared highly densified composite electrodes of graphene and single-walled carbon nanohorns (SWCNHs) using a simple spray-drying method that is suitable for mass production. To prepare the high-density composite electrodes, water-based mixtures of oxidized SWCNHs (NHOs) and graphene oxides (GOs) were spray-dried in heated air; after spray-drying, GOs dispersed in water were agglomerated in spherical clusters containing NHO nanoparticles. The reduced spray-dried GO/NHO (rS-GO/NHO) composite electrodes exhibited an extremely high bulk density of 1.23 g·cm−3, which is almost double that of commercial activated carbon (AC) and reduced NHO (r-NHO) electrodes, and three times higher than that of rS-GO electrodes. Of the materials tested, the rS-GO/NHO composite electrode had the highest volumetric capacitance (80 F·cm−3 at 1 mA·cm−2) and a low sheet resistance (0.005 Ω· sq.−1), which are far superior to those of commercial AC (57 F·cm−3 at 1 mA·cm−2 and 0.293 Ω·sq.−1, respectively), without the need for a conductive material, such as carbon black. We expect that these high-density graphene/SWCNH composite electrodes with high volumetric capacitances can be substituted for commercial AC materials in energy storage devices, such as supercapacitors.

The generation of hydrogen from water represents an important task towards a carbon neutral economy. Within this context, the preparation of hybrid electrodes merging the versatility of solid-state porous substrates and the catalytic ability and tunability of molecular complexes represents a great challenge. In the present work, we report on the preparation of hybrid cathodes for the hydrogen evolution reaction (HER) through an unprecedented combination of single-walled carbon nanohorns (SWCNHs) and two novel cobalt(II) polypyridine complexes based on the tris(2-pyridylmethyl)amine (TPMA) ligand scaffold. Suitable pyrene groups are introduced in the ligand framework in different positions to provide a way for direct anchoring onto the carbonaceous substrate by exploiting non-covalent π–π interactions. The present systems behave as competent cathodes for the HER in neutral aqueous solution with overpotentials of η ∼ 0.5 V and stable current densities (within 1 h electrolysis) up to −0.50 mA cm−2, whose exact values depend on the catalyst used and are mainly related to the respective loading on the electrode surface. In both cases, hydrogen evolution is detected under continuous electrolysis for up to ca. 12 h leading to maximum turnover numbers (TONs) of 4700 and 9180 molH2 molCo−1 for the two different complexes. The progressive deactivation under electrolytic conditions is mainly ascribed to leaching of the metal centre from the polydentate ligand, likely occurring from the competent catalytic intermediates involved in the HER.

The high surface area and electrical conductivity of few-layered graphene would make it an ideal catalyst support and electrode in fuel cells apart from its susceptibility to oxidative corrosion. Here we report the single-step, bottom-up synthesis of oxidation-resistant boron-doped graphene and show its increased stability in the aggressive electrochemical environment of intermediate temperature solid acid fuel cells (SAFCs). Boron was shown to alter the growth mode of single walled carbon nanohorns by laser vaporization to produce high yields of thin ( 140 °C, with large fractions of multilayered B-GLFs surviving 10 °C/min ramps to 1000 °C. These B-GLFs provided a stable Pt catalyst support and electrode over 40 h operation in SAFCs with cesium dihydrogen phosphate electrolyte operating at 250 °C, as opposed to undoped GLFs or SWCNHs which were nearly completely consumed. The facile synthesis and oxidation-resistant properties of boron-doped GLF appear promising for graphene applications in oxidizing environments.

Pt-based catalysts supported onto various carbon nanotubes (CNTs) and carbon black Vulcan XC-72 have been studied in this work. The samples have been prepared via electrochemical dispersion technique. The carbon nanotubes exhibit the mesoporous morphology with the pore size of 5—30 nm, while Vulcan XC-72 support exhibits a microporous structure. The agglomeration of Pt particles (5—7 nm) is found to be more extended at the carbon nanotubes compared to the carbon black. The examination of the synthesized catalysts in a catalytic membrane electrode assembly layer reveals that CNTs favor a power density higher than in the carbon black support owing to a more suitable porous structure of the catalyst layer. Moreover, the maximum characteristics of membrane electrode assembly are obtained for few-walled carbon nanotubes with a broad carbon having size distribution.

This report deals with a simple and efficient method to develop hybrid carbon nanoparticles (Nps) employing Multi-walled carbon nanotubes (MWCNTs) and Fullerene nps. Fullerene nps were self-assembled via Ultrasonicated Liquid-Liquid Precipitation. Surface treated MWCNTs were entangled with fullerene nps during the process of assembling of the fullerene nps. Fullerene nps are formed by reaction between two solutions, one is the saturated solution which contains dissolved fullerene and other solution is a rough alcohol. This reaction increases the concentration of carbon in the solution and leads to super saturate hence self-assembling into nanoparticles. The obtained hybrid nanoparticles sizes were in the range of 100 nm to 300 nm with entangled mwcnts and were confirmed by characterization using SEM, Raman, UV-Vis, XRD, and DLS.

Whereas vertically aligned carbon nanotubes (VACNTs) typically show a promising adsorption behavior at high pressures, carbon nanohorns (CNHs) exhibit superior gas adsorption properties in the low pressure regime due to their inherent microporosity. These adsorption characteristics are further enhanced when both materials are opened at their tips. The so prepared composite material allows one to investigate the effect of physical entrapment of CO2 molecules within the specific adsorption sites of VACNTs composed of opened double walled carbon nanotubes (CNTs) and in specific adsorption sites created by spherically aggregated opened single walled carbon nanohorns. Combining 50 wt% of tip opened CNTs with tip opened CNHs increases the CO2 adsorption capacity of this material by ∼24% at 30 bar and 298 K compared to opened CNHs alone.

Boron- and nitrogen-codoped single walled carbon nanohorns (BN-SWCNHs) were prepared by CO 2 laser ablation of a boron-containing carbon target under nitrogen atmosphere. The structures were spherical SWCNH aggregates containing many graphite-like thin sheets (GLSs), which was different from general SWCNHs. X-ray photoelectron spectra indicated that the doped quantities of boron and nitrogen were about 1.2 and 1.0 at.%, respectively. The boron and nitrogen atoms were implanted partially as the BN bonding in a graphene lattice, although they were also implanted individually as three-fold coordinated sp 2 bonding. The boron-doped GLSs were preferentially prepared by CO 2 laser ablation of a boron-containing carbon target under argon atmospheres. As a result, we found that the boron accelerated the formation of GLSs. The simple CO 2 laser ablation method will be useful for heteroatoms doping into carbon nanohorns.

In this study, Titania (TiO 2 ) based composites reinforced with 2 wt% of various carbon nanomaterials were prepared using spark plasma sintering (SPS). Prior to SPS, the samples were ball milled. The reinforcements used in the composites were graphene nanoplatelets (GNP), carbon nanotubes (CNT) and single walled carbon nanohorns (SWNH). The ball milled powders and SPS compacts were characterized using various techniques. Mechanical and photocatalytic properties of the SPS composites were evaluated and compared for different nano-carbon reinforced TiO 2 composites. X-ray diffraction and Raman spectroscopy studies confirmed that the milled powders comprised of Anatase phase which transformed into Rutile phase during SPS. Nano transformation twins were observed in Rutile grains. Fractured surfaces showed that the reinforcements were well bonded with the TiO 2 grains and the SWNH reinforcement resulted in comparatively finer grain size. Nanoindentation studies showed that the hardness and elastic modulus of GNP reinforced composites was 78% and 30% respectively higher compared to TiO 2 matrix. The hardness and modulus of the CNT reinforced TiO 2 increased by 22% and 5.4% respectively while that of the SWNH reinforced TiO 2 increased by 11% and 23% respectively. GNP and CNT reinforced TiO 2 exhibited superior photocatalytic activity for the degradation of methylene blue dye compared to pure TiO 2 .

The effect of different surfactants on the removal efficiency of wiping surfaces contaminated with single walled carbon nanohorns (SWCNHs) was studied. To this end, sodium dodecylbenzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) surfactants were used, and their removal efficiencies with water only and with cleaning with a dry wipe were compared. The surfactant concentrations and wipe pressure during the wiping process were varied, and significant effects on removal efficiency were found. In addition, the results were compared with those obtained with single-walled carbon nanotubes (SWCNTs) and multi-walled CNTs (MWCNTs) and the differences among these nanostructures were reported. The results suggest that SDS and SDBS are good candidates for removal of SWCNHs deposited on silicon wafers with SDS removal efficiencies capable of exceeding 90%. In addition, the results show that there is an optimum wiping pressure and surfactant concentration with the highest removal efficiency. A direct relationship was also found between wipe saturation and removal efficiency of SWCNHs deposited on silicon substrates. The differences between individual nano structures were perceptible in spite of following similar broad trends; for instance, SWCNH contaminated surfaces in general proved more difficult to clean than surfaces contaminated with the other nanostructures.

Adsorption of polyethylene glycol conjugated phospholipids with various PEG chain length (DSPE-PEG5000, 2000, 750) onto single-walled carbon nanohorns (SWCNH), a type of graphene nano-tubule, in aqueous solution was investigated by means of high-resolution magic angle spinning (HRMAS) 1H NMR. Peak integral ratio of PEG chains and alkyl chains of DSPE-PEGs in the NMR spectra linearly decreased to zero with the increase of SWCNH quantity, indicating that the adsorption of DSPE-PEGs on SWCNH was virtually irreversible. The area of SWCNH surface allocated to the individual DSPE-PEG5000, 2000, 750 molecule were estimated to be 7.06, 5.18, and 4.45 nm2, respectively. Coverages of the alkyl chains on the surface area of SWCNH were about 28%, 39% for DSPE-PEG5000, 2000 and 46% for DSPE-PEG750, suggesting single layer adsorption. We presumed that the electrostatic repulsion may prevent DSPE-PEGs from multiple layer and keep away neighbouring DSPE-PEGs on the surface. According to the molecular areas of the DSPE-PEGs, PEG5000 and 2000 chains were considered to be in brush-regimes, while PEG750 was considered to be in mushroom regime on the SWCNH surface.

The unique water transport properties in nanospaces are essential for control of various chemical reactions, biochemical activities, and electrochemical systems. Fast water transport has been observed in one-dimensional nanospaces. However, water transport via zero-dimensional nanospaces has not yet been observed. Zero-dimensional nanospaces were obtained by extremely small and thin gate (zero-dimensional gate) insertion on graphene walls of single-walled carbon nanohorns. The water transport properties were examined by water vapor loading and release via the zero-dimensional gates, and molecular dynamics simulation. Although relatively large gates provided considerable adsorption hysteresis by long-term equilibrium, water vapor loading and release via the extremely small gates showed consecutive water loading and release. The molecular dynamics simulation showed consecutive water transport via the gates, probably because of lower energy barriers to water transport in the vicinity of the gates. The zero-d...

Two kinds of luminescent nanoprobes were developed for Pb2+ detection based on luminescence resonance energy transfer (LRET) by using sodium citrate functionalized upconversion nanoparticles (Cit-UCNPs) as the energy donor and single-walled carbon nanohorns (SWCNHs) or graphene oxide (GO) as the energy acceptor. A Pb2+ aptamer 5′-NH2-(CH2)6-GGGTGGGTGGGTGGGT-3′ (denoted as pDNA) sequence was assembled with Cit-UCNPs to form the Cit-UCNPs–pDNA. By using the SWCNHs (or GO) as matrix, the final Cit-UCNPs–pDNA–SWCNHs (or Cit-UCNPs–pDNA–GO) nanoprobe can be obtained, in which the LRET process happened and the upconversion luminescence of the probe was quenched. With the addition of Pb2+, a stable G-quadruplex–Pb2+ complex was formed, which results in the separation between Cit-UCNPs–pDNA nanoparticles and SWCNHs (or GO) and the recovery of the upconversion luminescence. The two turn-on luminescence probes could detect Pb2+ ions from amongst other ions with high sensitivity and selectivity in aqueous solution. To the best of our knowledge, a nanoprobe for the detection of Pb2+ ions based on LRET between UCNPs and SWCNHs (or GO) has not been reported in the literature to date. This work demonstrates a simple yet powerful sensing strategy, which may open up potential perspectives for environmental monitoring applications.

With the growth of the global economy and population, the demand for energy is increasing sharply. The development of environmentally a benign and reliable energy supply is very important and urgent. Single-walled carbon nanohorns (SWCNHs), which have a horn-shaped tip at the top of single-walled nanotube, have emerged as exceptionally promising nanomaterials due to their unique physical and chemical properties since 1999. The high purity and thermal stability, combined with microporosity and mesoporosity, high surface area, internal pore accessibility, and multiform functionalization make SWCNHs promising candidates in many applications, such as environment restoration, gas storage, catalyst support or catalyst, electrochemical biosensors, drug carrier systems, magnetic resonance analysis and so on. The aim of this review is to provide a comprehensive overview of SWCNHs in energy applications, including energy conversion and storage. The commonly adopted method to access SWCNHs, their structural modifications, and their basic properties are included, and the emphasis is on their application in different devices such as fuel cells, dye-sensitized solar cells, supercapacitors, Li-ion batteries, Li-S batteries, hydrogen storage, biofuel cells and so forth. Finally, a perspective on SWCNHs’ application in energy is presented.

Cost-effective synthesis of single walled carbon nanotube (SWCNT) and single walled carbon nanohorn (SWCNH) hybrids, in a single step, by electric arc discharge technique in open air, at lower current densities is reported. The rate of production of the hybrids is 3-5 g/h. The presence of SWCNTs and SWCNHs is confirmed by a transmission electron microscope (TEM). In addition to conventional larger Dahlia-like aggregates of nanohorns, unique nearly-spherical shaped and relatively smaller sized aggregates (mean size ? 25 nm) of nanohorns are formed along with thin bundles (mean diameter ? 5.7 nm) of SWCNTs. � 2015 Elsevier B.V. All rights reserved.

Mixtures of straight and defect-free multiwalled carbon nanotubes (MWCNTs), single walled carbon nanohorns (SWCNHs), and multiwalled carbon nanohorns (MWCNHs) were prepared by the arc discharge method. Functionalized Carbon Nanotubes (FCNTs) composed of MWCNTs, MWCNHS and SWCNHs were obtained using acid functionalization process. TiO2/FCNTs (CTP) nanohybrid photocatalysts were obtained with different amounts of FCNTs (2-20 wt%), by wet impregnation method. The photocatalytic activity of both pristine TiO2 as well as the nanohybrids were studied in aqueous glycerol solution under solar irradiation. Reaction parameters such as amount of catalyst and amount of FCNTs in nanohybrids were optimized to ensure high rates of H2 production. With a relatively low amount of pristine TiO2, a high rate of H2 production of 2134 ?mol h-1 gcat -1 has been obtained and is likely due to several factors such as well dispersed catalyst, reduced particle-particle agglomeration, resulting in enhanced light absorption (less light shielding), improved separation of charge carriers and utilization for red-ox reactions. Even better results were obtained with the use of nanohybrid catalysts. The enhanced photocatalytic activities of the nanohybrid catalysts are ascribed to the synergetic effects of FCNTs that minimize light reflection which promotes enhanced solar light sensitization, good dispersion of the catalysts in the reaction solution, and improved surface-interface reactions of photogenerated charge carriers. In the present study 10 wt% FCNTs in nanohybrid (CTP-10) exhibited superior photocatalytic activity for H2 generation, nearly 3 times higher than that of pristine TiO2 catalyst. The CTP-10 photocatalyst exhibited photostability under the experimental conditions studied. The nanohybrid photocatalysts were characterized in order to confirm the crystal structure, morphology, surface chemical composition and optical properties. The present work demonstrates the unique beneficial photocatalytic properties of carbon nanotubes and nanohorn mixtures in nanohybrid photocatalysts, for enhanced H2 production. � 2014 Hydrogen Energy Publications, LLC.

Fluorination is one of the most effective chemical methods to modify and control the physical and chemical properties of carbon materials, which have been applied without exception to carbon nanotubes. One of the most significant advances in the fluorine chemistry of single-wall carbon nanotubes (SWNTs) in recent years is finding the fluorine storage properties of the SWNTs and of single-wall carbon nanohorns (SWNHs). As another important feature of the recent fluorine chemistry of SWNTs, it can be mentioned that understanding the versatile interaction of fluorine with curved hybrid networks of sp 2 -like carbon atoms has been becoming much clearer, which is closely related to the fluorine storage properties of SWNTs and SWNHs. In light of the recent developments in the studies of the fluorine chemistry of SWNTs and SWNHs, this chapter focuses on the thermal fluorination–defluorination of the SWNTs and SWNHs, and their fluorine storage properties.

Graphene sheets have been synthesized from single walled carbon nanohorns by one-step reaction with hydrogen peroxide. The obtained graphene sheets are in pure form and shows good electrical properties. As-synthesized graphene acts as dual function of support as well as reducing agent to prepare graphene-silver nanoparticle composite having uniform particle size of 6 nm. This method can easily be scalable to prepare graphene or graphene supported metal nanoparticle composites for versatile applications.

Graphene is possibly the thinnest membrane that could be used as a molecular separation gate. Several techniques including absorption, cryogenic distillation, adsorption, and membrane separation have been adopted for constructing separation systems. Molecular separation using graphene as the membrane has been studied because large area synthesis of graphene is possible by chemical vapor deposition. Control of the gate sizes is necessary to achieve high separation performances in graphene membranes. The separation of molecules and ions using graphene and graphene oxide layers could be achieved by the intrinsic defects and defect donation of graphene. However, the controllability of the graphene gates is still under debate because gate size control at the picometer level is inevitable for the fabrication of the thinnest graphene membranes. In this paper, the controlled gate size in the graphene sheets in single-walled carbon nanohorns (NHs) is studied and the molecular separation ability of the graphene sheets is assessed by molecular probing with CO2, O2, N2, CH4, and SF6. Graphene sheets in NHs with different sized gates of 310, 370, and >500 pm were prepared and assessed by molecular probing. The 310 pm-gates in the graphene sheets could separate the molecules tested, whereas weak separation properties were observed for 370 pm-gates. The amount of CO2 that penetrated the 310 pm-gates was more than 35 times larger than that of CH4. These results were supported by molecular dynamics simulations of the penetration of molecules through 300, 400, and 700 pm-gates in graphene sheets. Therefore, a gas separation membrane using a 340-pm-thick graphene sheet has high potential. These findings provide unambiguous evidence of the importance of graphene gates on the picometer level. Control of the gates is the primary challenge for high-performance separation membranes made of graphene.

Septicemia is a serious disease that requires early diagnosis, and procalcitonin (PCT) serves as a diagnostic biomarker for this disease. Traditional clinical detection (via immune-gold chips) remains difficult and expensive. An electrochemical immunosensor based on new nanomaterials may provide a solving approach. Herein, an ultrasensitive sandwich electrochemical strategy for PCT detection was developed. Firstly, reduced graphene oxide (rGO)–gold (Au) nano-composite film was used as the immunosensor platform to increase the amount of PCT antibody 1(Ab 1 ) immobilized. Next, single-walled carbon nanohorns (SWCNHs)/hollow Pt chains (HPtCs) complex was firstly utilized to label PCT Ab 2 as signal tags. For SWCNHs with few side effects, high surface area and HPtCs with higher specific surface, better catalytic activity, complex synthesized from both may provide more advantages. Moreover, to amplify signal, HPtC catalytic activity with H 2 O 2 was enhanced by horseradish peroxidase (HRP) for dual synergy amplification. The whole results demonstrated that the proposed immunosensor exhibited fast operation, high sensitivity, good reproducibility, acceptable stability and ideal selectivity compared with traditional method. The linear calibration of the immunosensor ranged from 1.00 pg/mL to 2.00×10 1 ng/mL with a detection limit of 0.43 pg/mL. Analytical application results revealed that the immunosensor matched with the real concentrations of serum samples. Overall this immunosensor may provide a new alternative strategy for PCT detection.

A study of synthesis of multi-walled carbon nanotubes (MWNTs) and carbon sphere and also their electrochemical performance for the storage hydrogen gas has been presented. The structure and the morphology of carbon nanostructures have been investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy. Furthermore, the electrochemical hydrogen adsorption properties of MWNTs and carbon spheres were elucidated by galvanostatic charge/discharge and cyclic voltammetric measurements. The electrochemical results demonstrated that carbon spheres synthesized from sucrose and starch exhibited hydrogen adsorption of ∼0.9 and 1 wt% respectively. Whereas, the multiwalled carbon nanotubes have exhibited hydrogen adsorption of ∼1.2 wt%.

The effect of dispersion of Fe/Fe2O3 nanoparticles in sulfonated single-walled carbon nanohorns (SO3H/SWCNHs) on their catalytic activity for the esterification of palmitic acid was investigated. A gas-injected arc-in-water (GI-AIW) method was employed to initially synthesize SWCNHs dispersed with iron nanoparticles (Fe-SWCNHs). The Fe-loading amount in the Fe-SWCNHs was varied by changing the number of Fe wires inserted in an anode. The results showed that Fe-loading amount proportionally increased from 6 to 13 wt% with an increase in the number of Fe wires. The surfaces of the Fe-SWCNHs were functionalized with acid functional groups by two sequential steps: impregnation of sulphuric acid and calcination in air. From the characterization results, their acid site concentrations were estimated to be 5.6–8.5 mmol g−1, suggesting that the catalyst was a solid superacid catalyst. XRD analyses indicated that most of the Fe was transformed to α-Fe2O3. The catalytic activity of the SO3H/Fe-SWCNHs for the esterification of palmitic acid was evaluated to investigate the influence of the Fe-loading on their catalytic activity. The results showed that the yield of methyl palmitate was significantly enhanced by an increase in the Fe-loading amount. It was discovered that the catalytic activity and the magnetic susceptibility of SO3H/Fe-SWCNHs can be preserved during repeated use, if the Fe-loading amount is large enough.

Carbon nanoparticle-modified multi-wall carbon nanotubes were prepared using a dehydration of carbohydrate compound method. The structural change was characterized by transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett and Teller measurement. Fast adsorption kinetics was observed for multi-wall carbon nanotubes with modification, as demonstrated by the adsorption of the model compound methylene blue. This work provides a novel facile engineering strategy to equip multi-wall carbon nanotubes with fast adsorption kinetics, which is promising for efficient water purification.

The degradation behavior of porous scaffolds plays an important role in the synthesis of new tissue. In this study, three-dimensional hybrid porous scaffolds of chitosan (CS) comprised of nanostructured carbon (graphene oxide (GO) and single-walled carbon nanohorns (SWCNH)) were prepared by freeze-drying method. In-vitro degradation behavior of scaffolds was investigated up to 8 weeks in phosphate buffer saline (PBS) solution at 37 °C. The characteristics of scaffolds explored as a function of degradation time include crystalline structure, pore morphology, molecular weight, and wet/dry weight. The pH value of the PBS solution during degradation was also monitored. The study demonstrates for the first time that hybrid chitosan scaffolds with nanostructured carbon (GO and SWCNH) are potentially more stable than pure chitosan scaffolds during the time period required for tissue regeneration. The stability of hybrid scaffolds is attributed to nanostructured carbon that was processed with the objective that it is present in a robust manner via a highly cross-linked dense network structure. The chemical structure of chitosan was disrupted within a short period of two weeks, while disruption occurred in hybrid scaffolds after eight weeks. This was accompanied by a weight loss of ∼28% in pure chitosan and ∼20% in hybrid scaffolds. Furthermore, the degraded products were of low molecular weight in pure chitosan and high molecular weight in hybrid chitosan scaffolds. This led to significant decrease in the pH of solution to ∼6.2 in pure chitosan and to ∼7.2 in hybrid scaffolds. The observations clearly underscore that the introduction of GO and SWCNH via cross-link mechanism in CS is a potentially viable approach to tune the degradation rate of hybrid scaffolds in tissue engineering.

Single-walled nanohorns (SWNHs) have been prepared by sub-merged arc discharge of graphite electrodes in liquid nitrogen. The samples were examined by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Nitrogen and boron doped SWNHs have been prepared by the sub-merged arc discharge method using melamine and elemental boron as precursors. Intensification of Raman D-band and stiffening of G-band has been observed in the doped samples. The electrical resistance of the SWNHs varies in opposite directions with nitrogen and boron doping. Functionalization of SWNHs through amidation has been carried out for solubilizing them in non-polar solvents. Water-soluble SWNHs have been produced by acid treatment and non-covalent functionalization with a coronene salt. SWNHs have been decorated with nanoparticles of Au, Ag and Pt. Interaction of electron donor (tetrathiafulvalene, TTF) and acceptor molecules (tetracyanoethylene, TCNE) with SWNHs has been investigated by Raman spectroscopy. Progressive softening and stiffening of Raman G-band has been observed respectively with increase in the concentration of TTF and TCNE.

The structure of dahlia-type single-walled carbon nanohorn aggregates has been modeled by classical molecular dynamics simulations, and the validity of the model has been verified by neutron diffraction. Computer-generated models consisted of an outer part formed from single-walled carbon nanohorns with diameters of 20-50 Å and a length of 400 Å and an inner turbostratic graphite-like core with a diameter of 130 Å. The diffracted intensity and the pair correlation function computed for such a constructed model are in good agreement with the neutron diffraction experimental data. The proposed turbostratic inner core explains the occurrence of the additional (002) and (004) graphitic peaks in the diffraction pattern of the studied sample and provides information about the interior structure of the dahlia-type aggregates.

Nitrogen-doped single-walled carbon nanohorns (N-SWCNHs) have been synthesized by a flowing nitrogen assisted arc discharge method at atmospheric pressure in a tubular reactor. X-ray diffraction and thermogravimetric analysis have revealed their high quality. Scanning electron microscopy and transmission electron microscopy examinations have shown that N-SWCNHs have typical spherical structure with a diameter of 40–80 nm. Oxidation treatment suggests the opening of cone-shaped caps of N-SWCNHs. The FT-IR and X-ray photoelectron spectroscopy analysis indicate that most of the nitrogen atoms are in N-6, N-5, and triple-bonded CN bonding configuration present at the defect sites or the edges of graphene layers.

Multi-walled carbon nanotubes were synthesized by Chemical Vapor Deposition on supported Ni/SiO2 using carbon monoxide as carbon source. The effect of Ni loading and feed gas on carbon nanotubes was studied. The yield of carbon was very low when Ni loading was 5% and the yield increased with the increase of Ni loading from 5% to 35%. Then the yield decreased after Ni loading is over 35%. The carbon nanotubes were characterized by TEM, HRTEM and XRD. It was found that the morphology of carbon nanotubes became poor with the increase of Ni loading. The optimum reaction temperature is 600℃ from both aspects of carbon yield and morphology. Without hydrogen in the feed gas, the diameter of carbon nanotubes was in a narrow range of 10~20nm. After hydrogen was introduced to the system, the amount of carbon was enhanced but the morphology became worse.

In the present research paper carbon nanostructures viz. single walled carbon nanotubes, multi-walled carbon nanotubes, single walled carbon nanohorns and graphene nanoplatelets have been synthesized by CVD technique, hydrothermal method, DC arc discharge method in liquid nitrogen and microwave technique respectively. After synthesis 5 mm thick pallets of given nanomaterial are prepared by making a paste in isopropyl alcohol and using polyvinylidene difluoride as a binder and then these pallets were used for nanoindentation measurements. Hardness, reduced modulus, stiffness, contact height and contact area have been measured using nanoindenter.

Fibrous aggregates composed of radially assembled graphene-based single-walled nanotubules are prepared, named here as fibrous aggregates of single-walled carbon nanohorns (fib-CNHs), whose structure resembles that of chenille stems. The newly discovered fib-CNHs are 30-100 nm in diameter and 1-10 μm in length. The fib-CNHs show high dispersibility and conductivity. The fib-CNHs increase the advantages of nanocarbons in various fields.

Half-metallicity in carbon nanotubes is achieved and controlled by hydrogen adsorption patterns. The edge states in carbon nanotubes are unstable under an electric field due to the spin-conserving electron transfer between the edges, but a large enough transfer barrier between the edge states, obtained by controlling the adsorption patterns, renders the CNTs half-metallic.

A new dispersive micro solid-phase extraction method which uses single-walled carbon nanohorns (SWNHs) as sorbent is proposed. The procedure combines the excellent sorbent properties of the nanoparticles with the efficiency of the dispersion of the material in the sample matrix. Under these conditions, the interaction with the analytes is maximized. The determination of polycyclic aromatic hydrocarbons was selected as model analytical problem. Two dispersion strategies were evaluated, being the functionalization via microwave irradiation better than the use of a surfactant. The extraction was accomplished by adding 1 mL of oxidized SWHNs (o-SWNHs) dispersion to 10 mL of water sample. After extraction, the mixture was passed through a disposable Nylon filter were the nanoparticles enriched with the PAHs were retained. The elution was carried out with 100 μL of hexane. The limits of detection achieved were between 30 and 60ngL(-1) with a precision (as repeatability) better than 12.5%. The recoveries obtained for the analytes in three different water samples were acceptable in all instances. The performance of o-SWNHs was favourably compared with that provided by carboxylated single-walled carbon nanotubes and thermally treated carbon nanocones.

Carbon nanotubes grown from discrete Fe-containing nanoparticles dispersed on a silicon nitride transmission electron microscope grid were systematically studied. The (n,m) indices of produced single-walled carbon nanotubes (SWNTs) were deduced from their electron diffraction patterns. Relatively small diameter SWNTs with a narrow diameter distribution (0.7-1.6 nm) were produced using CO as the carbon source at 800 °C, while large diameter SWNTs ranging from 1.0 nm to 4.7 nm were synthesized when using CH(4) as the carbon source. The chiral angle distributions of the SWNTs produced from different carbon sources are also different, which are attributed to the preferred cap nucleation associated with the carbon feed rate on the catalyst instead of carbon nanotube growth kinetics. Furthermore, growth of carbon laminar nanoclusters inside carbon nanotubes was achieved at a higher growth temperature, suggesting that dissociated carbon diffuses across the nanoparticle during the nanotube growth process.

The effects of gamma-irradiation on the modification of the surface and structure of multi-walled carbon nanotubes were studied. Gamma-irradiation affected the graphitization properties of functional groups, and decreased the diameter of multi-walled carbon nanotubes. The irradiated multi-walled carbon nanotubes with the absorbed dose of 100 kGy exhibited a larger specific surface area and microporous volume as compared with the other samples. The Raman spectroscopy and X-ray photoelectron spectroscopy showed that the interaction between the gamma-irradiation and the multi-walled carbon nanotubes with the absorbed dose of 150 kGy destroyed the nanostructure of carbons, leading to the formation of diamond-like structures and carbon oxides. In addition, gamma-irradiation with the absorbed dose of 100 kGy improved multi-walled carbon nanotubes graphitization and surface properties while at higher absorbed dose (150 kGy), it induced damaged structures (sp 3 bonds and oxygen compositions).

This paper reviews progress that has been made in the use of Raman spectroscopy to study graphene and carbon nanotubes. These are two nanostructured forms of sp2 carbon materials that are of major current interest. These nanostructured materials have attracted particular attention because of their simplicity, small physical size and the exciting new science they have introduced. This review focuses on each of these materials systems individually and comparatively as prototype examples of nanostructured materials. In particular, this paper discusses the power of Raman spectroscopy as a probe and a characterization tool for sp2 carbon materials, with particular emphasis given to the field of photophysics. Some coverage is also given to the close relatives of these sp2 carbon materials, namely graphite, a three-dimensional (3D) material based on the AB stacking of individual graphene layers, and carbon nanoribbons, which are one-dimensional (1D) planar structures, where the width of the ribbon is on the nano...

Synthesis of carbon nanotubes from V-type pyrolysis flame is a kind of new method. It has potential for carbon nanotubes preparation in mass production. Carbon monoxide was as carbon source and the acetylene/air premixed gas provides heat by combustion. Hydrogen/helium premixed gas acted as diluted and protection gas. Pentacarbonyl iron was served as catalyst. Carbon nanotubes with less impurity and high yield were captured successfully in the V-type pyrolysis flame. The diameter of carbon nanotubes was approximate between 10nm and 20nm, and its length was dozens of microns. The size of catalyst nanoparticles approximately was from 5 nm to 8nm in diameter. This study aims to examine the formation process of typical carbon nanotubes from pyrolysis flame and to characterize their morphology and structure. The morphology and structural of carbon nanotubes were characterized by scanning electron microscope and transmission electron microscopy respectively. Temperature was the key parameter in the process of synthesis carbon nanotubes. The concentration of catalyst had important influence on the synthesis of carbon nanotubes. Sampling time directly determined whether carbon nanotubes formation was completely. The carbon “dissolved-proliferation-separate out” theory can be used to explain that pentacarbonyl iron catalyses carbon monoxide in the process of carbon nanotube formation.

A novel composite is presented as a supercapacitor electrode with a high maximum power rating (990 kW/kg; 396 kW/l) exceeding power performances of other electrodes. The high-power capability of the electrode stemmed from its unique meso-macro pore structure engineered through the utilization of single-walled carbon nanotubes (20 wt %) as scaffolding for single-walled carbon nanohorns (80 wt %). The novel composite electrode also exhibited durable operation (6.5% decline in capacitance over 100 000 cycles) as a result of its monolithic chemical composition and mechanical stability. The novel composite electrode was benchmarked against another high-power electrode made from single-walled carbon nanotubes (Bucky paper electrode). While the composite electrode had a lower surface area compared to the Bucky paper electrode (280 vs 470 m(2)/g from nitrogen adsorption), it had a higher meso-macro pore volume (2.6 vs 1.6 mL/g from mercury porosimetry) which enabled the composite electrode to retain more electrolyte, ensuring facile ion transport, hence achieving a higher maximum power rating (970 vs 400 kW/kg).

In this study, carbon nanotubes were formed from camphor oil decomposition on Fe/Ni/Mg catalysts at 650°C by fluidized floating catalyst method. X-ray diffraction (XRD) was used to examine the characteristics of carbon nanotubes. The carbon nanotubes were also examined both by FESEM and Raman spectroscopy to define their appearance and structure which revealed that dense bundle of mixed multi-walled and single-walled carbon nanotubes. The diameters of the single-walled carbon nanotubes were estimated to be around 0.86–2.31 nm. Little amount of carbon nanotubes were found on the Fe/Ni/Mg catalyst surface at 550°C; while a significant amount of carbon nanotubes were observed at 650°C. According to the XRD spectrum, there was carbon and graphite present in the deposited samples. Raman spectroscopy revealed two peaks at 1347–1357 cm−1 (D band, disorder mode, amorphous carbon) and 1572 cm−1 (G band, graphite sp2 structure). FESEM results indicated the Fe/Ni/Mg could catalyze the camphor oil decomposition to form carbon nanotubes even at a lower temperature.

Nanoparticles have significant potential as selective photo-absorbing agents for laser based cancer treatment. This study investigates the use of single walled carbon nanohorns (SWNHs) as thermal enhancers when excited by near infrared (NIR) light for tumor cell destruction. Absorption spectra of SWNHs in deionized water at concentrations of 0, 0.01, 0.025, 0.05, 0.085, and 0.1 mg/ml were measured using a spectrophotometer for the wavelength range of 200-1,400 nm. Mass attenuation coefficients were calculated using spectrophotometer transmittance data. Cell culture media containing 0, 0.01, 0.085, and 0.333 mg/ml SWNHs was laser irradiated at 1,064 nm wavelength with an irradiance of 40 W/cm{sup 2} for 0-5 minutes. Temperature elevations of these solutions during laser irradiation were measured with a thermocouple 8 mm away from the incident laser beam. Cell viability of murine kidney cancer cells (RENCA) was measured 24 hours following laser treatment with the previously mentioned laser parameters alone or with SWNHs. Cell viability as a function of radial position was determined qualitatively using trypan blue staining and bright field microscopy for samples exposed to heating durations of 2 and 6 minutes alone or with 0.085 mg/ml SWNHs. A Beckman Coulter Vi-Cell instrument quantified cell viability of samples treated with varyingmore » SWNH concentration (0, 0.01, 0.085, and 0.333 mg/ml) and heating durations of 0-6 minutes. Spectrophotometer measurements indicated inclusion of SWNHs increased light absorption and attenuation across all wavelengths. Utilizing SWNHs with laser irradiation increased temperature elevation compared to laser heating alone. Greater absorption and higher temperature elevations were observed with increasing SWNH concentration. No inherent toxicity was observed with SWNH inclusion. A more rapid and substantial viability decline was observed over time in samples exposed to SWNHs with laser treatment compared with samples experiencing laser heating or SWNH treatment alone. Samples heated for 6 minutes with 0.085 mg/ml SWNHs demonstrated increasing viability as the radial distance from the incident laser beam increased. The significant increases in absorption, temperature elevation, and cell death with inclusion of SWNHs in laser therapy demonstrate the potential of their use as agents for enhancing photothermal tumor destruction.« less