Papers by Keyword: Nanotube

Abstract: In this work, different ferrocene concentration (1.0-8.0 wt%) of bio-hydrocarbon palm oil precursor were utilized to investigate its effect on the characteristics of the produced carbon nanotubes (CNT). The palm oil-ferrocene mixture was vaporized at 450°C and pyrolyzed at 800°C for 30 min time in argon ambient. The CNT were analyzed using field emission scanning electron microscopy, scanning transmission electron microscopy, fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The analysis confirmed different diameter and morphologies of CNT were formed when different ferrocene concentration were used. FTIR spectra show the prominent peak at ~1445, 1736, 2851 and 2925 cm^-1 that are identified as CNT and C–H_x respectively.

Abstract: In this study we report the effect of various synthesis temperatures of 600 - 1000°C for the synthesis of carbon nanotubes (CNT). Bio-hydrocarbon precursor namely palm oil was utilized as a starting material by thermal vapor deposition method. Ferrocene at 5.33 wt% was directly mixed with palm oil precursor for 30 mins synthesis time. The prepared CNT was collected from the furnace wall and then characterized by field emission scanning electron microscopy, scanning transmission electron microscopy, fourier transform infrared spectroscopy and thermogravimetric analysis. The density, diameter and the purities of the CNT were found to be highly dependent on the temperature changes. The synthesis temperature of 800°C was considered to be the optimum temperature for higher quality and quantity of CNT production.

Abstract: In this paper, self-organized TiO₂ nanotubes (TNT) were synthesized by electrochemical anodization in different electrolytes comprising acidic fluorinated aqueous electrolyte and organic neutral electrolyte. The structural, morphological and composition of TNT were characterized with XRD, FESEM and EDX. Compared with aqueous electrolyte, much smoother tubes with an increase of over 30 times in nanotube length can be obtained by anodization in organic electrolyte. Besides the high aspect ratio, variation of nanotube length within the array could be observed. Interestingly, under the same heat treatment condition, choice of electrolyte has an influence on the crystalline structure of TNT.

Abstract: We investigate the prospect of methane gas storage in carbon nanotubes, and in particular we determine the interaction energy between a methane molecule and (9, 5), (8, 8) and (10,10) carbon nanotubes. Employing the Lennard-Jones potential together with the continuous approximation, we determine analytically the interaction energy for a methane molecule inside a carbon nanotube. Our results indicate that larger tubes are highly favoured sites for methane storage although smaller tubes might be superior for methane adsorption at higher temperatures, especially in the range 400 − 500 K.

Abstract: Nitrogen-doped titania nanotubes (TiO2-xNx NTs) were synthesized by the soft chemical process, in which nitrogen-doped titania nanopowders (TiO2-xNx NPs) reacted with strong alkaline solutions (10M). The properties of TiO2-xNx NTs were examined. Experiments on the photodegradation of methylene blue (MB) and sulfosalicylic acid (SSA) were also carried out under visible light irradiation.

Abstract: Four types of boron nitride (BN) nanotubes are selectively synthesized by annealing porous precursor in flowing NH3 and NH3/H2 atmosphere at temperature ranging from 1000 to 1200°C in a vertical furnace. The as-synthesized BN nanotubes, including cylinder, wave, bamboo and bubble-chain, are characterized by scanning and transmission electron microscopy. Selectivity of BN nanotubes is estimated as approximately 80 to 95%. The porous precursor B31Fe17(MgO)27 prepared by self-propagation high-temperature synthesis (SHS) method plays a key role in controllable synthesis of the as-grown BN nanotubes. The chemical reaction and annealing mechanism are also discussed.

Abstract: High-yield and high-purity bamboo-like boron nitride nanotubes were synthesized via an effective chemical vapor deposition method by annealing porous precursor under ammonia atmosphere at 1150 °C. The porous precursor, prepared by self-propagation high temperature synthesis method, was the key to bulk synthesis process. The as-synthesized boron nitride nanotubes were characterized by SEM, TEM, HRTEM, XRD, Raman and FTIR spectroscopy. These nanotubes had a bamboo-like structure with uniform diameters about 90 nm and length of more than 10 μm. The associated growth model is proposed in this paper.

Abstract: Titania nanotube arrays were fabricated in deionize water and glycerol mixed electrolyte containing a certain amount of NH₄F. Three different polishing methods were used for pretreatment of Ti substrates: polished by hand with abrasive paper, by polishing machine, or by chemical polishing fluid (HF:HNO₃=1:4, in volumetric ratio). The morphology of three different samples were imaged by scanning electron microscopy, and their photoelectrical properties were studied as well. Experimental results showed that Titania nanotube arrays grown on the Ti substrate and polished by polishing fluid has highly-ordered and well-defined nanotube structure. The effects of anodization potential and duration on synthesis of highly-ordered TiO₂ nanotubes were also studied in this paper. Both the layer thickness and nanotube diameter linearly increase with the increasing potential. The layer thickness also increases with prolongation of anodization time. By optimizing the preparation conditions, we can successfully control the geometrical structure of TiO₂ nanotube arrays with diameters in the range between 50 and 200 nm and the layer thickness between 800 and 2000 nm.

Abstract: In this paper, we have successfully synthesized polyaniline nanotubes by using chemical oxidation polymerization. This synthesis is simple and an effective way to prepare one-dimensional polymer nanotubes. By transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FTIR), the morphology and physical structures of the as-prepared products were characterized. By cyclic voltammetry we studied the electrocatalytic activity of polyaniline nanotube modified glassy carbon electrode on ascorbic acid. The results show that the polyaniline nanotube modified electrode has excellent electrocatalytic activity on ascorbic acid. Compared with those of the bare glassy carbon electrode, the anodic peak potential of ascorbic acid shifts negatively 0.212 V on the modified electrode, and the anodic peak current increases 43 %. And the concentration of ascorbic acid shows a good linear relation at the range of 1.0×10^-5 ~ 0.1 M with the minimum detection limit of 1.0 × 10^-6 M.

Abstract: In this paper, we have investigated the geometries and electronic structures of B-N co-doped carbon nanotube with inside adsorption of water molecules. The charge distributions, band structures and local density of states are calculated by using the first-principles theory in detail. The results show that the water molecules can adsorb stably on the inside surface of the doped nanotube with slight deformation. The π and π* subbands shift upward depending on the sites of the adoptions. The investigations will be beneficial to the biological application of B-N co-doped nanotube.