Preparation and magnetic property of multiwalled carbon nanotubes decorated by Fe3O4 nanoparticles

Iron oxide (Fe3O4) nanoparticles with average sizes of 6 and 10 nm were synthesized by a chemical co-precipitation method from mixtures of FeCl2·4H2O and FeCl3·6H2O. They were ultrasonicated with HNO3-oxidized MWCNTs in a solution (water/ethanol=1:1v/v) to carry out the decoration. The structure and properties of as-obtained Fe3O4/MWCNT composites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometry, X-ray diffraction and thermal gravimetry. Results showed that the Fe3O4 contents in the composites were 26.6 and 29.3% for particle sizes of 6 and 10 nm, and their saturation magnetizations were 16.5 and 7.5 emu·g−1 respectively.