Novel one-pot sol-gel synthesis route of Fe_3C/few-layered graphene core/shell nanoparticles embedded in a carbon matrix

Abstract

Fe_3C/few-layered graphene core/shell nanoparticles embedded in a carbon matrix are synthesized by a novel two-step surfactant sol-gel strategy, where the processes of hydrolysis, polycondensation and drying take place in a one-pot. The present approach is based on the combined action of oleic acid and oleylamine, which act sterically on the precursor micelles when a densification temperature is performed in a reducing atmosphere. The structural and magnetic evolution of the formed compounds is investigated, ranging from iron oxides such as Fe_3O_4 and FeO, to the formation of pure Fe_3C/C samples from 700 degrees C onwards. Interestingly, Fe_3C nanoparticles with a size of similar to 20 nm crystallize immersed in the carbon matrix and the surrounding environment forms an oriented encapsulation built by few-layered graphene. The nanostructures show a saturation magnetization of similar to 43 emu/g and a moderate coercivity of similar to 500 Oe. Thereby, an innovative chemical route to produce single phase Fe_3C nanoparticles is described, and an effective method of few-layered graphene passivation is proposed, yielding a product with a high magnetic response and high chemical stability against environmental corrosion.