Synthesis, characterization and magnetic properties of Co@Au core-shell nanoparticles encapsulated by nitrogen-doped multiwall carbon nanotubes

Co/Au bilayer thin films were deposited on Si/SiOx substrates using the magnetron sputtering method and used as a catalytic support to grow forests of aligned nitrogen-doped multiwalled carbon nanotubes (N-MWCNT) via chemical vapor deposition (CVD) at 850 °C, using benzylamine (C6H5CH2NH2) as a carbon and nitrogen source. Interestingly, the resulting N-MWCNT contains Co@Au core-shell nanoparticles located at their tips. We found that the metal particle cores consist of cobalt coated by an Au shell of few nanometers. Magnetic measurements revealed a ferromagnetic behavior of the system composed of Co@Au nanoparticles encapsulated inside N-MWCNT. The results are compared with pristine N-MWNT containing only Co nanoparticles encapsulated in their cores.