Large-Scale Synthesis of Single-Walled Carbon Nanohorns Using the Arc in Liquid Method

A novel and cost effective method has been developed for large-scale synthesis of single-walled nanohorns (SWNHs). This is the first report of an alternative method to laser ablation for formation of carbon nanohorns. The method is based on igniting an arc discharge between two graphite electrodes submerged in liquid nitrogen. Production rates of up to 17g/hr have been achieved. SEM analysis shows the nanohorns to be aggregated as nanoparticles with sizes in the range of 20~80nm. HRTEM reveals the internal structure of individual nanoparticle is an aggregation of either dahlia-like or bud-like single-walled nanohorns (SWNHs). It was further found that both the yield and morphology of nanohorns changed as a function of arc current density in liquid nitrogen. The yield of nanohorns increases with the increment of current density. Samples produced by higher current density contains more dahlia-like nanohorns than bud-like compared to those produced at lower current. The carbon arc in liquid nitrogen method holds the potential for controlling the structure of nanohorns as well as for allowing their production in large scale quantities required for applications such a fuel cell electrodes.