Synthesis of Highly Magnetic Iron Carbide Nanoparticles via a Biopolymer Route

In this article, we report a facile, one-pot route to phase-pure Fe3C nanoparticles (mean diameter = 20 nm) that show a remarkably high saturation magnetization (∼130 emu/g), higher than iron oxide (Fe3O4) and comparable to that of bulk Fe3C (∼140 emu/g). A readily available biopolymer (gelatin) is used as a matrix to disperse an aqueous iron acetate precursor. On heating, the biopolymer induces nucleation of magnetite (Fe3O4) nanoparticles before decomposing to form a carbon-rich matrix. This then acts as a reactive template for carbothermal reduction of the magnetite nanoparticles to Fe3C at a moderate temperature of 650 °C. This method represents a considerable advance over previous reports that often use high-energy procedures or costly and hazardous precursors. These homogeneous, highly magnetic nanoparticles have many potential applications in biomedicine and catalysis.