Preparation of A New Carbon Nano-particle by Arc Discharge
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Preparation of A New Carbon Nano-particle by Arc Discharge Bean-Jon Li, Sheng-Chin Kung, Chih-Ming Hsu, Jhy-Yeong Gao, Hong-Jen Lai Materials Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, Taiwan, R.O.C. ABSTRACT Synthesis and characterization of a new carbon particle are investigated in this study. The carbon particle, which possesses a very high surface area (682 cm2/g), is suitable for catalysts loading in application of fuel cell. As well known, carbon materials are used to be a support of Pt catalyst to achieve high dispersion to enhance the activity of Pt. The synthesis was performed by conventional arc discharge process between two graphite electrodes in vacuum. A high-current range from 100~ 300 ampere was utilized to evaporate the cathode electrode in order to produce carbon soot onto the wall of chamber, and further high production rate of 10 g/hr was achieved. The morphology and microstructure of the materials were investigated by SEM, HRTEM, XRD and Raman spectroscopy. Observations of the soot by SEM and HRTEM have shown that it consists agglomerations of carbon particles linked each other to form a chain-like structure. Most carbon particles are approximate 30 ~ 60 nm in diameter. HRTEM observation reveals that a carbon particle is comprised of several defective onions with different diameters and extremely curled graphene sheets, which appear as double-sheet layers. INTRODUCTION Many carbon materials, such as fullerene (C60), carbon nanotube (CNTs) and sing-wall carbon nanohorn (SWNHs), have been received attention for their characteristics and potential for use in various applications. The main methods for currently synthesizing these carbon materials are arc discharge, chemical vapor deposition (CVD) and laser ablation. The discovery of the structure of CNTs by Iijima in 1993 [1] was a scientific milestone. CNTs have attracted intense interest in the field of nanotechnology because of their unique properties and wide range of applications. Moreover, SWNHs was discovered in 1999 [2], which consist of horn-shaped sheath aggregate of single-wall graphene. The interhorn-wall distance is 0.4 nm, being greater than the interlayer spacing of graphite (0.335 nm) [3]. Thus SWNHs aggregates have been shown to adsorb ethanol effectively, about 3.5 times larger than that of a super high surface area carbon [4]. SWNHs are synthesized by laser ablation method without metal catalyst and are associated with each other to form the dahlia flower-like structured aggregate whose average diameter is about 80 nm [5]. This study reports the synthesis of a new carbon material without catalytic metal by arc discharge between two graphite rods in vacuum. A carbon particle with fused-onion structures, which differs from typical CNTs and SWNHs , was found in the soot deposited on the wall of chamber. A possible mechanism is also discussed.
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EXPERIMENTAL DETAILS Two graphite rods with the same diameter (10 mm) were used as the electrodes for the
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