One-step synthesis of iron-oxide-loaded functionalized carbon spheres

Size- and surface-tunable carbon spheres loaded with iron-oxide (α-Fe2O3 or Fe3O4) nanoparticles have been obtained from 4-ferrocenyl-butyric acid via an easy one-step method in a solvothermal system. The composites obtained have been fully characterized by X-ray powder diffraction, scanning and transmission electron microscopy, Fourier transform infrared spectrometry, Raman spectrometry and vibrating sample magnetometry. The results show that the diameters and morphologies of the spheres can be tuned by adjusting the experimental parameters including the reaction temperature, time, medium, and precursor concentration. Most of the iron-oxide nanoparticles are evenly distributed on the surface of the carbon spheres and also the surface of the iron-oxide-loaded carbon spheres has large numbers of functional groups. The α-Fe2O3-loaded carbon spheres show special magnetic properties with a coercivity of 101.5 Oe and a remanent magnetization of 0.203 emu/g at room temperature, while the coercivity and remanent magnetization for the Fe3O4-loaded carbon spheres are 58.4 Oe and 0.174 emu/g, respectively. A possible formation mechanism is proposed and discussed based on the features of the reaction system.