Lengthy one-dimensional magnetite (Fe₃O₄) sub-microfibers with excellent electrochemical performance

One dimensional Fe₃O₄ sub-microfibers with an average diameter of about 920nm and length of about 25μm were prepared by hydrothermal synthesis in the presence of sodium citrate (Na₃cit). The physicochemical properties were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). It was found that Fe₃O₄ crystal nuclei were generated from different Fe²⁺-citrate complexes under hydrothermal conditions and Na₃cit as a capping agent promoted the formation of Fe₃O₄ microfibers. The Fe₃O₄ nanocrystals grew along the (110) axis on the exposed (111) facet, and then further formed microfibers via an oriented attachment mechanism during the collisions. Polyvinylpyrrolidine (PVP) was more conducive to microfibers growth in comparison to polyethyleneglycol 4000 (PEG-4000), cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The electrochemical measurements show that the Fe₃O₄ sub-microfibers had a specific capacitance of 117.6Fg^-1 with good cycling performance.