抄録
Single-walled carbon nanohorns (SWCNHs) can be produced by an arc-in-water system, in which N2 gas is injected in an arc plasma zone in a hollow graphite cathode. To decrease the cost for synthesis, it is important to optimize the reaction condition when low cost electrodes (low purity graphite) are used because high purity graphite is fairly costly. In the present study, graphite electrode of a low graphite purity (C:97.5%, SiO2:1.4%, Al2O3:0.38%, Fe2O3:0.29%, etc.) was used for the electrodes, and the investigation of the operational paramters in the N2-injected arc -in-water method was carried out regarding the depth of the hole on cathode and velocity of the electrode motion to keep the arc plasma. It was observed in a transmission electron microscope that the purity of the SWCNHs from the low-purity graphite electrodes seemed as 70-80 %. As a result, the cost to synthesize SWCNHs became one order magnitude lower compared with the conventional condition using high purity graphite electrodes. At this condition, the yield and the production rate of SWCNHs were about 8 % and 18 g/h, respectively. In addition, the mechanism of the effect of the above parameters is discussed based on the resident time and the concentration of carbon vapor inside the cathode hole.
