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 Fe ₃O₄/MWNT composites were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The electrochemical performance of a Fe₃O ₄/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 Na₂SO ₃ 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.