Synthesis of carbon-encapsulated copper nanoparticles by the electrical explosion of wire method

The synthesis of carbon-encapsulated copper nanoparticles (Cu & C NPs) by the high-productive method of the electrical explosion of wire (EEW) is presented. Copper wire was evaporated by high-energy electrical current pulses. Evaporation of Cu and the consequent condensation of spherical nanoparticles took place in argon with the controlled addition of butane, which provided encapsulation of copper nanoparticles in carbon shells. Carbon was deposited in the form of several graphite layers, which completely covered the surface. The encapsulation diminished the agglomeration of carbon-encapsulated copper nanoparticles (Cu@C NPs) during their condensation and substantially diminished their average diameter. Upon the deposition of about 4 % of carbon, the average diameter of nanoparticles decreased more than three-fold - from 130 to about 40 nm. Simultaneously, the specific surface area of Cu@C NPs increased from 7 to 35 m2/g. The deposited dense and gas tight carbon shells protected the surface of particles from oxidation. It prevented the self-ignition of as-synthesized nanoparticles at the exposure to ambient air and provided stability to oxidation during long-term storage as well.