Preparation of Fe3O4@C composite nanoparticles with core-shell structure in subcritical water condition

Abstract

Fe3O4@C composite nanoparticles with core-shell structure were prepared. The carbon shell was accomplished by the cracking and carbonization of oleic acid (OA) in the subcritical water condition. The cracking products absorbed on the surface of Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD), differential scanning calorimetry-thermogravimetric (DSC-TG) curves, Raman and Fourier transform infrared (FTIR) spectra. The results proved the occurrence of the shell structure with a thickness of 10 nm and it was mainly composed of carbon materials with disordered and crystal structure, which could reach 30% of the mass of Fe3O4. The Reactive Force Field (ReaxFF) molecular dynamic was employed to simulate the cracking process of OA. It is found that the dissociation of CC bonds in OA could lead to the formation of hydrocarbon fragments, which further recombined to form graphite sheet and amorphous carbon, finally mixed and absorbed on the surface of Fe3O4 to form a carbonaceous shell.