In Situ Synthesis of Iron/Nickel Sulfide Nanostructures-Filled Carbon Nanotubes and Their Electromagnetic and Microwave-Absorbing Properties

We present a one-step chemical vapor deposition method to prepare iron/nickel sulfide nanostructures-filled carbon nanotubes (CNTs) by pyrolysis of dimethyl sulfide on stainless steel substrate. Dimethyl sulfide is used as the carbon, and sulfur source, and the stainless steel substrate acts as both the catalyst and support The as-grown products were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, and the results demonstrate that the encapsulated compounds in CNTs are Fe7S8 and Ni17S18 with hexagonal crystal structure. The possible growth mechanism is proposed. The complex permittivity and permeability of the CNT composites were measured at a frequency range of 2-18 GHz, and the microwave-absorbing performance was analyzed. With a matching thickness of 2 mm, the maximum reflection loss is about -29.58 dB at 14.80 GHz for the absorber. The bandwidth corresponding to the reflection loss at -10 dB is more than 5.58 GHz. The strong reflection loss is mainly caused by the magnetic loss originating from the encapsulated two-component sulfide nanostructures.