Abstract: Graphite surfaces were bombarded with oblique Arþ ions at 1 keV to induce the carbon nanofiber (CNF) growth at room temperature and at high temperature (300 oC), and their dependence of length, diameter and number density on ion-incidence angle and sputtering rate was investigated in detail. The sputtered surface ion-irradiated at normal incidence produced huge cones and rod-like structures. It was found that some of the cones possessed the non-aligned thick carbon fibers on the top. By contrast, obliquely ion-irradiation induced the formation of densely distributed CNF-tipped cones. The higher ion-incidence angle produced CNF of smaller diameter and high fabrication temperature favors the formation of
longer fiber with higher numerical density. In addition, the number density of the CNF-tipped cones strongly depended upon the ion-incidence angle rather than the sputtering rate. Thus, the diameter, length and number density of CNFs were strongly dependent upon the ion-irradiation parameters. It is believed that myriad of applications is possible with ion-induced CNFs by selecting the suitable ion-irradiation parameters.
Abstract: The synergistic combinations of organic polymers for separation applications with inorganic substances such as multi-walled carbon nanotubes (MWNTs), have resulted in a new class of membrane material called mixed matrix membrane (MMM) for the separation of CO2/CH4 gases. Mixed matrix membrane incorporated functionalized MWNTs (f-MWNTs) were fabricated by the solution casting method, in which the f-MWNTs were embedded into the polyimide membrane and the resulting membranes were characterized. The effect of nominal MWNTs content between 0.5 and 1.0 wt% on the gas separation properties was investigated. The mixed matrix membranes showed 100% enhancement for the selectivity of CO2/CH4 compared to the corresponding neat polymer membrane. This new class of mixed matrix membrane has the ability to separate gases at the molecular level and has the potential to ultimately reduce the energy consumed in present-day separation operations. This study has shown that addition of CNTs to polymeric membranes has improved separation properties of the membranes to a certain extent.
Abstract: This paper presents direct growth of horizontally-aligned carbon nanotubes (CNTs) between two predefined various inter-spacing up to tens of microns of electrodes (pads) and its use as CNT field-effect transistors (CNT-FETs). Using the conventional photolithography technique followed by thin film evaporation and lift off, the catalytic electrodes (pads) were prepared, consisting of Pt, Al and Fe triple layers on SiO2/Si substrate. The grown CNTs were horizontally-aligned across the catalytic electrodes on the modified gold image furnace hot stage (thermal CVD) at 800 oC by using an alcohol vapor as the carbon source. Scanning and transmission electron microcopies (SEM/TEM) were used to observe the structure, growth direction and density of CNTs, while Raman spectrum analysis was used to indicate the degree of amorphous impurity and diameter of CNTs. Both single- and multi-wall CNTs with diameters of 1.1–2.2 nm were obtained and the CNT density was controlled by thickness of Fe catalytic layer. Following horizontally-aligned growth of CNTs, the electrical properties of back-gate CNT-FETs were measured and showd p-type conduction behaviors of FET.
Abstract: Carbon nanofibers (CNFs) with a diameter of 17 nm, and carbon nanoneedles (CNNs) with sharp tips have been synthesized on graphite substrates by ion irradiation of argon ions with the Co supplies rate of 1 and 3.4 nm/min, respectively. Energy dispersive X-ray spectrometry, combined with selected area electron diffraction patterns has been used to identify the chemical composition and crystallinity of these
carbon nanostructures. The CNFs were found to be amorphous in nature, while the structures of the CNNs consisted of cubic CoCx, orthorhombic Co2C and Co3C depending on the cobalt content in the CNNs. The diameter of the carbide crystals was almost as large as the diameter of the CNN. Compared to the ioninduced nickel carbides and iron carbides, the formation of single-crystalline cobalt carbides might be due to the high temperature produced by the irradiation.
Abstract: Direct growth of aligned metal composite carbon nanofibers (MCNFs) was achieved by a highly reproducible room temperature growth process on cost effective electrically conductive
copper (Cu) substrate without any catalyst. The direct fabrication of MCNFs on electrically conductive substrate might offer new perspectives in the field of field emission displays (FEDs).
Abstract: Single-walled carbon nanotubes (SWNTs) have been used successfully to fabricate highly transparent and flexible field emission displays (FEDs). Field emission measurements indicated
that SWNTs films have great potential to work as building blocks for next generation transparent and flexible FEDs.
Abstract: We report the synthesis of poly[(3-hexylthiophene)-block-(3-(4,4,5,5,6,6,7,7,7 nonafluoroheptyl)thiophene)], P(3HT-b-3SFT), carried out by the Grignard Metathesis Method (GRIM). The copolymers composition was determined by 1H and 19F NMR spectroscopies, and gel permeation chromatography (GPC). The thin films of P(3HT-b-3SFT) were investigated by ultraviolet-visible absorption spectroscopy and atomic force microscopy (AFM). We also fabricated bulk-hetero junction (BHJ) solar cells based on blends of P(3HT-b-3SFT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Although the composition ratio of P3SFT in P(3HT-b-3SFT) was low, the influence of P3SFT on the morphology and properties of solar cells was significant. The annealing process for the BHJ solar cells induced the formation of large domains and led to poor solar cell performance. The BHJ solar cells, based on PCBM and P(3HT-b-3SFT), prepared by the non-annealing process, had a maximum power conversion efficiency of 0.84% under 100 mW/cm2 (AM 1.5 solar illumination) in air.
