Carbon Nanotubes−Magnetite Nanocomposites from Solvothermal Processes: Formation, Characterization, and Enhanced Electrical Properties

Carbon nanotubes (CNTs)−magnetite nanocomposite with 20−30-nm magnetite particles attached onto CNTs has been successfully prepared for the first time by in situ solvothermal synthesis from the precursor of Fe−urea coordination complex (Fe[(NH 2 ) 2 CO] 6 (NO 3 ) 3 ) and CNTs. The effects of CNTs and various processing parameters on ultimate composites characteristics were investigated. It has been found that pure CNTs−magnetite nanocomposite was obtained in an ethylenediamine medium at 200 °C for 50 h with the weight ratio of Fe[(NH 2 ) 2 CO] 6 (NO 3 ) 3:CNTs = 10:1. XRD, BET, TEM, EDS, and a Mössbauer spectrum were used to characterize the final product. A possible formation mechanism of the CNTs−magnetite nanocomposite was suggested. It has been concluded that a suitable amount of water introduced by CNTs is critical for preparing CNTs−magnetite nanocomposite. The addition of CNTs in the composite increased the electrical conductivity by about 32% from 1.9 to 2.5 S cm -1, compared with the composite without CNTs. The relative density measurement and microstructure characterization performed by SEM showed that the percolation effect of CNTs and a good dispersion of CNTs in the matrix would lead to an effective and obvious improvement on the electrical conductivity.