Papers by Author: Cun Jing Wang

Abstract: Nano-carbon materials were synthesized by decomposing acetylene at 400 °C using iron supported on alumina as catalyst. The catalysts contain about 0.3 and 5.2 wt% iron. The products were refluxed in concentrated HCl at 80°C for 36 h in order to remove the catalyst support. The samples were examined by transmission electron microscopy and X-ray diffraction. The results show that carbon onions surrounding Fe3C core were obtained using the catalyst containing 0.3 wt% iron and these carbon onions had a structure of stacked graphitic fragments, with diameters in the range 15-50 nm.

Abstract: Carbon onions including Fe3C were synthesized by the catalytic decomposition of acetylene at 400 °C using iron supported on sodium chloride as catalyst. The samples were examined by high resolution transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The results show that carbon onions including Fe3C core with a structure of stacked graphitic fragments and diameters in the range 15-50 nm were obtained. When the product was further heat-treated under vacuum at 1100 °C, carbon onions with a clear concentric graphitic layer structure were obtained.

Abstract: The reactions were carried out by decomposing acetylene at 1000 °C in a two-stage furnace system for 10 min. In the first furnace no catalyst was placed and an AAO template with the average diameter about 50 nm was placed in the second furnace whose temperature was designed to be 500 °C, 600 °C and 700 °C. The samples were characterized by scanning electron microscopy and high resolution transmission electron microscopy. The results show that carbon spheres with average diameter about 50 nm on the AAO template surface were obtained when the temperature of the second furnace was designed to be 700 °C. These carbon spheres are composed of unclosed graphene layers with an interlayer distance of 0.33–0.35 nm between the layers.

Abstract: Nano-carbon materials were synthesized by catalytic decomposition of acetylene at low temperature 400 °C and 420 °C using iron supported on sodium chloride as catalyst. The samples were examined by X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained when the reaction temperature was 400 °C and there were no carbon nanotubes in the product. These onion-like fullerenes are composed of concentric graphene layers with an interlayer distance of 0.348 nm between the layers. When the reaction temperature was 420 °C, carbon nanotubes with a structure of rope and low graphitization degree were obtained.

Abstract: Carbon spheres were synthesized by chemical vapor deposition. The products deposited at different zones were separately collected. Furthermore, an anodic aluminum oxide template was used to control the size of carbon spheres. The products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that carbon spheres with controllable size distribution were obtained and the size distribution of these carbon spheres can be controlled to some degree by deposition zone and anodic aluminum oxide template.

Abstract: Both the catalytic property of the pore walls and the catalytic property of the top surface of AAO templates were closely investigated by pyrolizing acetylene at 650°C for 5min and 1h respectively. The conclusion that the top surface of the AAO template with smaller diameters has a stronger catalytic property was drawn. And the effects of the reaction time, the reaction gas flow rate and the location where the AAO template was placed on the properties of AAO templates were discussed. Furthermore, this paper proposed that in the competitive between catalyzes of AAO templates and the transition metal catalysts, the transition metal catalysts will play a dominant role in the formation of CNTs by adjusting the quantity of the transition metal catalysts embedded in AAO templates

Abstract: Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

Abstract: Synthesis of onion-like fullerenes was carried out by chemical vapor deposition in a tubular furnace using iron catalyst supported on aluminum hydroxide at 400°C, 460°C, 600°C, 700°C, 800°C, 900°C and 1000°C, respectively, in the presence of argon as carrier gas and acetylene as the carbon source. The samples synthesized were characterized by high-resolution transmission electron microscopy, and the effects of temperature on the morphologies of the samples were investigated. The results show that the onion-like fullerenes prepared at the low temperature 400°C had the highest purity and good quality.

Abstract: The reactions were carried out by decomposing acetylene at 1000 °C in a two-stage furnace system for 10 min. In the first furnace no catalyst was placed and an AAO template with average diameter about 50 nm was placed in the second furnace whose temperature was designed to be 700 °C. The samples were characterized by scanning electron microscopy and high resolution transmission electron microscopy. The results show that carbon spheres with average diameter about 50 nm on the AAO template surface were obtained and these carbon spheres are composed of unclosed graphene layers with an interlayer distance of 0.33–0.35 nm between the layers.

Abstract: Catalytic decomposition of acetylene was carried out at 400 °C using iron supported on sodium chloride as catalyst and the product was heat-treated at 650 °C under an argon atmosphere for 2 h directly. The sample was examined by scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained.