Low-cost synthesis of single-walled carbon nanohorns using the arc in water method with gas injection

A method of synthesizing bulk amounts of single-walled carbon nanohorns (SWNHs) on a significant low-cost basis is proposed based on the 'arc in water' method with N 2 injection into the arc plasma. It is elucidated that rapid quenching of the carbon vapour in an inert gas environment is necessary to form the delicate SWNH structures. To realize this reaction field, the arc plasma between the graphite electrodes was isolated from the surrounding water by a thin graphite wall with an N 2 flow that excluded reactive gas species (H 2 O, CO and H 2 ) from the arc zone. High concentrations of SWNHs were found as fine powders floating on the water surface. The particle size distribution of the SWNHs produced by this method was evaluated by dynamic light scattering, resulting in an approximately 70 nm peak diameter.