Synthesis and Characterization of Fe-C Core-shell Nanoparticles

Abstract

Magnetic nanoparticles are suitable for applications such as biosensing [1] and contrast agents for magnetic resonance imaging [2] etc. Iron nanoparticles have the advantage of high saturation magnetization for these applications. However, oxidation at ambient condition makes this advantage rarely available. Encapsulating iron nanoparticles by graphitic carbon is one of the solutions to this problem.In this work, Fe-C core-shell nanoparticles are successfully synthesized. The approach is similar to Kong's method for carbon nanotubes [3]. For the transmission electron microscopy (TEM) study, the nanoparticles are transferred to a holey carbon TEM grids by applying a drop of nanoparticle suspension to the grids which are then air-dried. A Philips CM300 TEM operated at 150KeV was used for the TEM study.

Synthesis and characterization of graphite-encapsulated iron nanoparticles from ball milling-assisted low-pressure chemical vapor deposition

“…The absence of non-encapsulated particles in our observation can thus be considered to be an important contribution of the current synthesis method and an advantage for possible medical applications. Unlike previous related investigations in the literature in which a maximum of 15 layers of graphitic carbon were reported [4,6,11–14,18,28,29,32,37–40], this study finds over 40 layers on some particles. The formation of multi-layered graphitic shells without observation of non-encapsulated nanoparticles could be the combined effect of homogeneous distribution of Fe 2 O 3 powders in graphite by ball milling prior to the LPCVD process and gas interaction with these reactants during a relatively long reaction time (3 h).…”

“…In particular, Fe, Ni and Co-based magnetic nanoparticles are preferred candidates for medical applications because of their high magnetization and catalyzing abilities [4,6,9,10]. However, they oxidize readily and the strategy has been to encapsulate them with a protective layer to prevent them from being oxidized or corroded [4,11–14]. Materials such as silica, boron nitride, noble metals and organic polymers have been used for such coating [15–22].…”

“…Chemical vapor deposition (CVD) has also been employed for the synthesis of CEMNPs under different pressure conditions such as high vacuum (10 −4 –10 −6 Torr), atmospheric pressure and low pressure (0.1–1 Torr) originating from metallic salts or metallic salt-loaded silica powders, metallocene precursors and ferrofluid-loaded silicon wafers [6,11–14,16,37–40]. The formation of non-encapsulated particles encountered in the above-mentioned methods can be avoided using CVD processes by increasing the interaction area and reaction kinetics through the introduction of a gaseous carbon source.…”