Carbon-coated cobalt nanoparticles

The nanocrystalline cobalt used in experiment was prepared by means of cobalt hydroxide precipitation, followed by calcination and reduction. A small amount of structural promoters (CaO and Al2O3) was added to stabilize the nanocrystalline cobalt structure at elevated temperatures. The fcc-Co and hcp-Co phases were determined in the prepared samples. The metal was carburised with methane in a temperature range 400-500 °C to obtain Co(C) nanocapsules. The carbon deposit was reduced with hydrogen flow in a temperature range 500-560 °C. Carburisation processes was investigated using thermogravimetric method. The samples after carburisation were investigated by means of XRD and HRTEM methods. Carbon-coated cobalt nanocapsules and carbon nanotubes were obtained.