Fabrication and microwave absorption of carbon $nanotubes∕CoFe2O4$ spinel nanocomposite

A large-scale carbon $nanotube∕CoFe2O4$ $(CNTs∕CoFe2O4)$ spinel nanocomposite has been fabricated by a chemical vapor deposition method using $CoFe2O4$ nanoparticles as catalysts. A uniform mixture of CNTs and $CoFe2O4$ nanoparticles was obtained simultaneously. The structure and chemical composition of the product were investigated using various techniques, such as x-ray diffraction, high-resolution transmission electron microscopy, and electron energy loss spectroscopy. It was found that the particles functionalized on CNTs were cubic phase $CoFe2O4$⁠. Microwave absorption of the $CNT∕CoFe2O4$ nanocomposites at 2–18 GHz is evidently enhanced, as compared with that of both pure CNTs and $CoFe2O4$ nanoparticles. The enhancement mechanism is discussed based on magnetization hysteresis loop measurement and electromagnetic theory.