Production of carbon nanoparticles using ARC discharge in water method

Abstract

'Arc in liquid' method has been recently developed as a low-cost technique to fabricate carbon nanostructures. In this work, the effects of organic liquid such as alcohols (C[subscript m]H[subscript 2m+1]OH, m=1-8), alkanes (C[subscript m]H[subscript 2m+2], m=6-7), and aromatic compounds (C[subscript 6]H[subscript 6]-C[subscript n]H[subscript 2n], n=1-2) as well as inorganic salt solution such as Na[subscript 2]CO[subscript 3], NiSO[subscript 4], CoSO[subscript 4] and FeSO[subscript 4] on the product structures and yield of nanocarbon-rich deposits were investigated. Multi-walled carbon nanotubes (MW-CNTs) and polyhedral nanoparticles were successfully produced with high concentration as the hard deposit formed at the cathode tip in all condition. When organic compounds were applied as liquid media, not only graphite electrodes but also organic liquid compounds as an additional carbon source to produce carbon nanoparticles which lead to approximately8-100 times higher yield than the 'arc in water' system. For inorganic salt solution system, the existence of ions, even only a little amount (0.01-0.05 M), in reaction zone could play an important role as a catalyst to enhance the formation rate of CNPs. Additionally, metallic byproduct compounds with various shapes depending on the aqueous concentration could be found in the synthesized products. By using surfactant (monoolein) to prepare the organic liquid-water mixture to accommodate the arc, n-hexane of which vapor pressure is 1,500-10,000 times lower than pure n-hexane compound, could be obtained. This is an effectively alternative method to provide more carbon atoms for reaction which could provide higher safety than using pure organic liquid.