Effect of arc current on characteristics of nanocarbons prepared by cryogenic arc discharge method

A variety of nanocarbons (nanohorns, nanoflowers and nanoclusters) could be prepared by arc discharge in cryogenic nitrogen with either graphite–graphite or iron–graphite electrodes manipulated by a strategy of automatic electrode delivering. Based on local thermal equilibrium assumption, magneto-hydrodynamic equations were taken into account for estimating the arc power efficiency of 60–84%, depending on the electrode combination. The effects of arc current on the morphology and yield of nanocarbons were investigated within a range of 75–150 A. Transmission electron microscopic analyses revealed that the synthesized product consisted of single-walled carbon nanohorns and multi-walled carbon nanoflowers with nominal diameters of 100–200 nm when graphite–graphite electrodes were employed but nanoclusters containing Fe nanoparticles inside carbon nanoshells with smaller size of 70–120 nm were mainly synthesized by iron–graphite electrodes subject to arc discharge in cryogenic nitrogen.