Tuning carbon content and morphology of FeCo/graphitic carbon core-shell nanoparticles using a salt-matrix-assisted CVD process

Large-scale and tunable synthesis of FeCo/graphitic carbon (FeCo/GC) core-shell nanoparticles as a promising material for multipurpose biomedical applications is reported. The high-quality graphitic structure of the carbon shells is demonstrated through high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman spectroscopy. A saturation magnetization of 80.2 emu g^-1 is reached for the pure FeCo/GC core-shell nanoparticles. A decrease in the saturation magnetization of the samples is observed with an increase in their carbon content with different carbon morphologies evolved in the process. It is also shown how hybrid nanostructures, including mixtures of the FeCo/GC nanoparticles and multi-walled carbon nanotubes (MWNTs) or carbon nanorods (CNRs), can be obtained only by manipulation of the carbon-bearing gas flow rate.