Surface of copper is easily oxidized and the resulting oxidation products cause an increase of the electric resistance which severely limits their applications. In this study, we tried to improve the electric conductivity of copper metal by replacement of the copper oxide with the copper bromide. As a result, we found that an increase of the concentration of cyclohexylamine hydrobromide (CHAB) used for bromination made it possible to keep a high electric conductivity of copper. Moreover, under the low CHAB concentration, suppress of the surface oxidation involved water content in the reaction media, which indicates that water influences the hold of copper bromide on the surface. Heat treatment accelerates the oxidation, however, for the brominated copper, decrease in the electric conductivity hardly observed even after the heat treatment at 100℃ for 4 h. These results show that the brominated copper on surface gives the oxidation resistance and the hold of copper bromide is influenced by the water content in the reaction media.
Solution plasma is a non-equilibrium plasma in liquid phase. The reaction field of solution plasma is novel and useful for a wide variety of material science and engineering applications. Active species such as radicals, electrons and ions are generated in the plasma. These active species react with chemicals in liquid at the interface between plasma (gas) and liquid and cause unique chemical reactions owing to variation of liquids, electrodes, as well as operational conditions. Until now, solution plasma process has been applied into the following applications; (1) nanoparticle synthesis, (2) surface modification of nanocarbon, (3) rapid synthesis of nanochannel carbon materials, (4) nanoparticle supported on nanocarbon, and (5) heteroatom-containing carbon substances synthesized from monomers.