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Scanning electron microscopy image of carbon nanotube-oxide composite formed by the selective reduction of the oxide solid solution in CH 4 + H 2 atmosphere at 1000 • C.
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Double-wall carbon nanotubes are the molecular analogues to coaxial cables. Narrow diameter double-walled carbon nanotubes (DWNTs) have been obtained by catalytic chemical vapour deposition process with high yield and characterized by scanning and transmission electron microscopy. We examine the inelastic light scattering spectrum of mostly DWNTs w...
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In this work, we evaluate the effect of ferrocene delivery in the reactor on the growth of single-walled carbon nanotubes (SWCNTs) in an aerosol CVD utilizing carbon monoxide as a feedstock. For this purpose, we assess the reactor output parameters varying a gas flow rate through a ferrocene vapor injector in the hot zone with other conditions (tem...
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... Figure 4 shows the TEM image of single-walled carbon nanotubes (SWCNT) [43]. Figure 5 shows high resolution TEM images of double-walled carbon nanotubes (DWCNTs) [44] and Figure 6 shows TEM images of multi-walled carbon nanotubes (MWCNTs) [45]. Figure 4 shows the TEM image of single-walled carbon nanotubes (SWCNT) where the diameter of the nanotube is about 1 nm. ...
... Figure 4 shows the TEM image of single-walled carbon nanotubes (SWCNT) [43]. Figure 5 shows high resolution TEM images of double-walled carbon nanotubes (DWCNTs) [44] and Figure 6 shows TEM images of multi-walled carbon nanotubes (MWCNTs) [45]. Figure 4 shows the TEM image of single-walled carbon nanotubes (SWCNT) where the diameter of the nanotube is about 1 nm Table 4. Types of Carbon Nanotubes (CNTs) and its attributes. ...
... License: https:// creativecommons.org/licenses/by/3.0/legalcode. Figure 5: Bacsa et al., 2003. This is an Open Access article which is distributed under the terms of the Creative Commons Attribution 3.0 International License (https://creativecommons.org/licenses/by/3.0/), ...
Bacterial flagella are complex multicomponent structures that help in cell locomotion. It is composed of three major structural components: the hook, the filament and basal body. The special mechanical properties of flagellar components make them useful for the applications in nanotechnology especially in nanotube formation. Carbon nanotubes (CNTs) are nanometer scale tube-shaped material and it is very useful in many applications. However, the production of CNTs is costly and detrimental to the environment as it pollutes the environment. Therefore, bacterial flagella have become a highly interesting research area especially in producing bacterial nanotubes that could replace CNTs. In this review article, we will discuss about bacterial flagellum and carbon nanotubes in the context of their types and applications. Then, we will focus and review on the characteristics of bacterial flagellum in comparison to carbon nanotubes and subsequently, the advantages of bacterial flagellum as nanotubes in comparison with carbon nanotubes.
... Another low frequency range of Raman peaks have to be overserved in the range of 100-400 cm −1 generally known as radial breathing mode (RBM). The peak intensity of RBM seems very weak or could be rarely observed to the large diameter of nanotubes [50]- [52]. RBM is proportionate to the diameter inversely, whereas the tangential stretching (G-band) mode depends on the diameter very weakly. ...
This paper proposes an integrated layered doped and undoped amorphous silicon thin-film based temperature sensing device. Temperature sensing performance has been measured for thin film p-i-n (p-type- intrinsic- n-type) configuration-based diode. Linear dependency of voltage on the temperature for forward-biased diode at a constant bias current is demonstrated in the temperature range of 30 - 200 °C. Further, the same device has been introduced with double-walled carbon nanotubes (DWCNTs) to improve the linearity of the sensor. Comparative performance of two configurations p-i-n and p-i-n/DWCNTs for temperature sensing application has been studied. Moreover, this paper discussed the effect of the DWCNTs on the sensor parameters such as sensitivity, S and coefficient of determination, R2. The maximum sensitivity of the sensor, 22.34 mV/ °C for p-i-n configured device and 21.06 mV/ °C for p-i-n/DWCNTs configuration in a biasing current range of 10- 60 mA have been found. We achieved a maximum value of the coefficient of determination equal to 0.99889 for a p-i-n configuration and 0.99922 for a p-i-n/ DWCNTs configured device.
... It is believed that the double-shell carbon cylinders would exhibit enhanced field emission, mechanical, thermal, and filters properties when compared to the single-walled nanotubes (Kim et al. 2004). The double-walled carbon nanotubes have been produced by several techniques such as the arc discharge method (Hutchison et al. 2001, Sugai et al. 2003, the catalytic chemical vapor deposition method (Bacsa et al. 2003), and a method utilizing fusion reactions of fullerenes in singlewalled carbon nanotube (Bandow et al. 2001(Bandow et al. , 2004. The double-walled carbon nanotube yield can be greater than 95% (Endo et al. 2005). ...
... The overall procedure is simple, because carbon can be chemically modified by covalent and noncovalent attachment of the molecules on its surface (Ajayan, 1999). Covalent functionalization implicates the elimination of the C double bonds, where carbon atoms change from sp 2 to sp 3 hybridization, leaving "holes" in the structure and, thus, modifying both their mechanical and electrical properties (Bacsa et al., 2003). ...
Biomimetics has paved the way toward new materials and technologies inspired in Nature. Biomolecules and their supramolecular organization have today a leading role in biomimetics, benefiting from the recent advances in nanotechnology.
The production of biomimetic materials may be however a difficult task, because Nature does it very well. The use of several building blocks assembled in bottom-up arrangement is without doubt at the core of this process. Such building blocks include different molecules or molecular arrangements, of synthetic or natural origin, such as amino acids, lipids, carbohydrates, nucleic acids, carbon allotropes, dendrimers, or organosilanes, among others.
The most common approaches to produce synthetic biomimetic materials are reported herein, with special emphasis to building blocks and their supramolecular arrangement.
... Thus, the intertube transfer is negligibly small and has no effect on transport properties of DWCNT [141] . By managing the electronic properties of CNTs (dependant on the orientation of the honeycomb lattice with respect to the tube axis, known as helicity), the neuroelectric nanosensor wires can be produced using DWCNTs [142] . Combining an internal CNT having metallic or semiconductor properties with an external nanotube having insulation properties gives a nanosensor wire that is a molecular analog of coaxial cable [142] . ...
... By managing the electronic properties of CNTs (dependant on the orientation of the honeycomb lattice with respect to the tube axis, known as helicity), the neuroelectric nanosensor wires can be produced using DWCNTs [142] . Combining an internal CNT having metallic or semiconductor properties with an external nanotube having insulation properties gives a nanosensor wire that is a molecular analog of coaxial cable [142] . ! ...
Neuronanorobotics, a key future medical technology that can enable the preservation of human brain information, requires appropriate nanosensors. Action potentials encode the most resource-intensive functional brain data. This paper presents a theoretical design for electrical nanosensors intended for use in neuronanorobots to provide non-destructive, in vivo, continuous, real-time, single-spike monitoring of action potentials initiated and processed within the ~86 x 10^9 neurons of the human brain as intermediated through the ~2.4 x 10^14 human brain synapses. The proposed ~3375 nm 3 FET-based neuroelectric nanosensors could detect action potentials with a temporal resolution of at least 0.1 ms, enough for waveform characterisation even at the highest human neuron firing rates of 800 Hz.
... 1605 cm −1 ) typical of defective graphite-like materials and usually observed for MWCNTs. 60 The ratio between the intensities of the D band and the G band, I D /I G (Table 1), decreases from G1R to G3R (0.37 and 0.15, respectively) but is markedly higher for G4R (0.60). An increasing I D /I G value corresponds to a higher proportion of sp 3 -like carbon, which is generally attributed to the presence of more structural defects. ...
Samples containing a majority of either single-wall carbon nanotubes (SWCNTs) or double-walled carbon nanotubes (DWCNTs) are prepared in the same catalytic chemical vapor deposition conditions but using slightly different catalytic materials, based on alumina impregnated with iron and molybdenum salts. There is a sharp SWCNTs-to-DWCNTs transition. By contrast to the usual findings, the selectivity is not correlated to the size of the iron-based catalyst nanoparticles, nor does the transition occur upon a decreasing carbon/catalyst ratio. The result is attributed to the increasing MoO3 concentration inducing modifications of the gas atmosphere, such as the formation of more reactive C-2 species through C2H4 dissociation, which thus favors the nucleation and growth of a DWCNT. In the DWCNT sample, the average diameter of the SWCNTs is higher than the average outer diameter of the DWCNTs, which is uncommon, as many authors stress that SWCNTs show a lower diameter than DWCNTs. The study could provide guidelines for the synthesis of very small diameter DWCNTs.
... It is not clear how the interaction between the walls, which can depend on diameter, affects the line shape of the 2D band. Finally, the RBMs of adjacent tubes are coupling and have not been observed for MWCNTs except for MWCNTs made of few, small diameter tubes [81]. MWCNTs also often contain more defects, giving rise to a large D band, although MWCNTs grown by the electric arc discharge method can have a much lower number of defects [82]. ...
... This will be discussed in more detail below. We find that the investigated DWCNTs on Au(111) have a diameter in the 2 to 4 nm range, which is typical for DWCNTs [18], and a length of the order of 1 mm, in agreement with atomic force microscopy observations.Figure 1(b) presents a high-resolution close-up view of a larger DWCNT with d = 3.6 ± 0.1 nm. ...
Double-wall carbon nanotubes (DWCNTs) are investigated with high resolution by scanning tunneling electron microscopy at 78 K and 4.5 K. Besides the atomic structure of the DWCNT surface, an additional honeycomb-type superstructure is revealed at these low temperatures. This periodic structure can be interpreted in terms of a Moiré pattern resulting from a rotation between the rolled up graphene sheets that constitute the DWCNT. Deviations of the observed Moiré patterns from the perfect hexagonal Moiré patterns that are commonly resolved for multi-graphene layer surfaces are found to be related to the intrinsic different curvature of the inner and outer tube of the DWCNT. Investigation of such Moiré patterns in the surface of DWCNTs allows one to gain more insight into the structure and chirality of the otherwise inaccessible inner shell of the DWCNTs.
... This resulted in a mat of composite powder (which density depended on the composition of the catalyst), which was then treated with a concentrated aqueous HCl solution (12 M) to separate the DWCNs by dissolving all the remaining oxide material, as well as unprotected metal particles. The suspensions were filtered and washed on cellulose nitrate membranes (Whatman, 0.45 lm) with deionised water until neutrality [17,18]. ...
... Intense G-peak is centered at 1582.6 cm À1 while a weak D-peak is observable centered at about 1343 cm À1 ; indicating their by that DWCNs have good graphitization and less amount of defects which may arise from the incorporation of pentagons, heptagons etc. Along with these, radial breathing mode peaks in the lower frequency region are also observable centered at 304.5 cm À1 , 283.2 cm À1 , 225.3 cm À1 , 199 cm À1 , 176.7 cm À1 and 146 cm À1 and are discussed in details earlier [17,18]. Fig. 3 shows the electron spin resonance (ESR) spectra of the DWCNs along with MgO:Mn 2+ as a reference measured at room temperature (25 °C). ...
Thick films of double walled carbon nanotubes (DWCN) were deposited on indium-tin-oxide (ITO) coated glass substrates by drop casting method and were studied for their field electron emission property in a parallel plate configuration using bare ITO coated glass as counter electrode. They show excellent field electron emission property with low turn-on-field of about 0.8 V/μm and threshold field of about 1.8 V/μm. Field enhancement factor calculated from the non-saturated region of the FN plot is about 1715. Field electron emission current was observed to be stable up to 3000 min, indicating thereby that DWCNs are excellent electron emitters with appreciable stable performance.
... A comparatively larger I D /I G ($0.85) indicates more strain on the sidewalls of CNTs as compared to ideal defect-free CNT, which is in agreement with the observations from XRD studies. Although, the D band depends on the number of defects and quality of the nanotubes, even higher quality tubes show a sharp and strong D band [32]. In addition, Raman peaks at 3152 and 2700 cm À1 correspond to the combination bands (overtones) due to D with G and D with D bands, respectively. ...
Felt-like mats (6–7 lm thick) of multiwalled carbon nanotubes wrapped into scrolls have been synthesized by chemical vapor deposition from a toluene–ferrocene mixture using a temperature ramp from 680 °C to 550 °C in hydrogen–argon atmosphere. Thermogravi-metric analysis reveals a very low catalyst content of ca. 1.25 wt% in the as-synthesized sample while, X-ray photo electron and Raman spectroscopies suggest the results match-ing with that of multiwalled carbon nanotubes. Considering, different time scales of vari-ous reactions and the diffusion of different reactants and products a tentative base growth mechanism has been proposed as per the available characterization data in conjunction with possible scrolling effects. Thermal expansion effects could explain a tentative mech-anism for rolling action of sheets. Interestingly, electrical conductivity measurements as a function of temperature suggest a semiconducting behavior, despite being governed by dif-ferent electron transport mechanisms with activation energies of 0.33 and 1.03 meV corre-sponding to two temperature ranges respectively. Cyclic voltammetry and electrochemical impedance analysis show a reversible redox behavior due to very low catalyst content and an irreversible etching of the Fe catalyst after acid treatment.
