Carbon-coated copper nanoparticles: Characterization and fabrication via ultrasonic irradiation

Carbon-coated copper nanoparticles can be obtained using sonochemistry and annealing at various temperatures. During annealing under an argon atmosphere, carbonization of organic species forms a carbon layer in the form of a shell, which plays an important role as a reducing agent in the phase transformation of copper oxide to copper. The annealed samples show two main peaks for Raman analysis, centered at 1349 cm−1 (D-band) and 1594 cm−1 (G-band), which are in good agreement with the pattern reported for graphite. The carbon shell was protected from the oxidation and decomposition in air and chemical environment. The shell of carbon-coated copper nanoparticle has pore sizes of 8.8 nm (adsorption) and 5.2 nm (desorption), and a surface area of 159.4 m2 g−1, respectively. Thus, carbon-coated copper nanoparticles, with a high surface area and good electrical conductivity and oxidation resistance in air and chemical solutions owing to the carbon layer, have great potential applications in industrial, environmental, and biological fields.