Roles of nanosized Fe3O4 on supercapacitive properties of carbon nanotubes

We synthesized Fe3O4 nanoparticle-dispersed multiwalled carbon nanotubes (MWNTs) to evaluate their potential applicability to supercapacitor electrodes. Nanosized Fe3O4 was deposited by chemical coprecipitation of Fe2+ and Fe3+ in the presence of MWNTs in alkaline solutions. Fe3O4 nanoparticles with an average particle size of 14 nm were prepared within several minutes. The structure and morphological characteristics of the Fe3O4/MWNT composites were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The electrochemical performance of a Fe3O4/MWNT composite electrode and a pure MWNT electrode was tested by cyclic voltammetry (CV) and galvanostatic charge-discharge in a sulfite electrolyte. The results showed that the Fe3O4/MWNT electrode had typical pseudo-capacitive behavior in a 1 M Na2SO3 solution and a significantly greater specific capacitance than that of the pure MWNT electrode. It could also retain 85.1% of its initial capacitance over 1000 cycles.