Scalable synthesis of dispersible iron carbide (Fe₃C) nanoparticles by ‘nanocasting’

Metal carbides have shown great promise in a wide range of applications due to their unique catalytic, electrocatalytic and magnetic properties. However, the scalable production of dispersible metal carbide nanoparticles remains a challenge. Here, we report a simple and scalable route to dispersible iron carbide (Fe 3C) nanoparticles. This uses MgO nanoparticles as a removable 'cast' to synthesize Fe 3C nanoparticles from Prussian blue (KFe III[Fe II(CN) 6]). Electron tomography demonstrates how nanoparticles of the MgO cast encase the Fe 3C nanoparticles to prevent sintering and agglomeration during the higherature synthesis. The MgO cast is readily removed with ethylenediaminetetraacetic acid (EDTA) to generate Fe 3C nanoparticles that can be used to produce a colloidal ferrofluid or dispersed on a support material.