Surface modification of graphite encapsulated iron nanoparticles by plasma processing

The graphite encapsulated iron nanoparticles were fabricated by using arc discharge method. The synthesized nanoparticles were pre-treated by an inductively-coupled RF Ar plasma and then post-treated by NH3 plasma under various gas pressures and treatment times. Analyses of XPS spectra have been carried out to study the effect of the plasma treatment on the surface modification of nitrogen-containing groups. The morphological changes of the particles surface by plasma treatment have also been analyzed by using HR-TEM. Present results show that the highest values of N/C atomic ratio of 5.4 % is obtained by applying 10 min of Ar plasma pre-treatment and 2 min of NH3 plasma post-treatment conducted in RF power of 80 W and gas pressure of 50 Pa.

Research Highlights
► The graphite encapsulated iron nanoparticles were treated by an inductively coupled RF plasma.
► The nanoparticles were characterized well using HR-TEM, XPS and EDS with elemental mapping.
► The inner structures of graphene layers and the iron cores were not damaged by plasma treatment.
► The surface of the outmost graphene layer was successfully covered by nitrogen-containing groups.
► The highest N/C atomic ratio of 5.4 % was achieved by 10 min Ar plasma and 2 min NH3 plasma treatments.