Papers by Author: Jin Cheng

Abstract: Fractal carbon films deposited on copper plate by ethanol chemical vapor deposition are reported. In order to prepare fractal carbon films, iron nitrate was employed as catalyst precursor, copper plate as substrate, and ethanol as carbon source materials. The as-prepared carbon films were characterized by employing scanning electron microscopy and Raman spectroscopy. The thickness of the film was a few micrometers. According to Raman spectrum, we know the films exhibit low graphitization. According to SEM observation, we find that there are many protuberances with nanometer scale tips on the film surface. Due to direct growth on metal substrate and many nanometer scale tips, it has potential application that is fit for electron source in vacuum devices.

Abstract: In this study, we report the synthesis of carbon nanotubes by ethanol catalytic chemical vapor deposition, which employs ferrocene as the catalyst precursors and ethanol as carbon source. We obtained massive deposits. The deposits were characterized by scanning electron microscopy, transmission electron microscopy, and visual laser Raman spectroscopy. We discussed the effects of synthesis temperature on the synthesis of carbon nanotubes by floating catalytic chemical vapor deposition. Our results indicated that the synthesis temperature could affect not only on the graphitization degree, but also on the aligned growth of carbon nanotubes and the diameter of carbon nanotubes.

Abstract: Well-aligned multi-walled carbon nanotube (MWNT) arrays were grown by floating catalyst chemical vapor deposition (CVD) on quartz substrate. The MWNTs in arrays had a uniform diameter of 30-50nm and high degree of graphitization. We find that catalyst nanoparticles with different sizes can be separated and deposit at different position by carrier gas flow under gravity effect in floating catalyst CVD. It is one of the main reasons that lead to the growth of well-aligned MWNTs.

Abstract: The straight Y-shaped silica nanorods have been synthesized on Si wafer by thermal chemical evaporation of mixed powders of silica and graphite at 1300°C and condensation on Si substrate without assistance of any catalyst. The synthesized samples were characterized by means of scanning electron microscopy, transmission electron microscopy. The results suggested that the straight Y-shaped silica nanorods have uniform diameter about 50-200nm and neat smooth surface. The growth of such silica nanorods may be a result of the fluctuation of external conditions causing a change in the growth direction of silica nanorods developed.

Abstract: A simple combustion technique is presented for the preparation of mono-sized silica nanoparticles by employing tetraethyl orthosilicates as precursor. The as-grown white powders were characterized by means of scanning electron microscopy. The results showed the size of silica nanoparticles were relative to the unique synthesis conditions. According to the observation and analysis of the scanning electron microscopy images, the possible growth mechanism of silica nanoparticles in this process is proposed.

Abstract: The straight silica nano-rods with a diameter of about 200nm and smooth surface were synthesized by chemical vapor deposition method at 1300°C. The as-synthesized samples were characterized by means of scanning electron microscopy, energy dispersive x-ray, and transmission electron microscopy. The results show that as-synthesized silica nano-rods have a uniform size, well-defined shape, and smooth surface. However, the morphologies and microstructures of silica nano-rods are affected by synthesis conditions, such as the concentration of the SiOx and the the deposition temperature. On the basis of these experimental results, a possible growth mechanism of silica nano-rods in this process is proposed.

Abstract: A simple catalytic combustion technique for synthesizing bamboo-like carbon was presented. Ethanol was used as carbon source and fuel, copper plate as substrate, and iron salt as catalyst precursors. The as-grown black powder was characterized by means of scanning electron microscopy, and transmission electron microscopy. The results show that the morphology and microstructure of bamboo-like carbon nanotubes are affected by novel synthesis conditions, such as concentration of catalyst precursor solution, synthesis time, flame perturbations, and synthesis temperature etc.. According to observations and analysis of experimental results, a possible growth mechanism of bamboo-like carbon nanotubes is proposed and discussed.

Abstract: Carbon nanotubes and carbon nanowires were synthesized by ethanol catalytic combustion (ECC) technique, using FeCl3 solution as a catalyst precursor. Applying the 0.01 mol/l, 0.1 mol/l and 1 mol/l FeCl3 as catalyst precursor solution to the copper plate, carbon nanotubes and carbon nanowires were synthesized. The effect of concentration on growth and structural changes of the as-grown nanomaterials are illustrated and discussed. This technique has advantages of low cost, large scale production and flexible reaction conditions, etc. This technique can be used to synthesize carbon nanotubes and nanowires on metal substrate directly. This technique also has potential applications for fabricating nano-electrical devices.

Abstract: Catalytic grown carbon nanofibers have been obtained from decomposition of ethanol over copper plate. Ferric chloride of different concentration was employed as the catalyst precursor. Scanning electron microscopy has shown that different morphologies of carbon nanofibers can be obtained by using different concentration of catalyst precursor solution. The results from the Raman spectroscopic characterization have also demonstrated that the graphitization of carbon nanofibers can be tailored by control of the concentration of catalyst precursor solution. When the information from these characterization are combined with that of the associated morphologies of the carbon nanofibers, it is possible to synthesize perfect carbon nanofibers.