Preparation and microwave absorption properties of multi-walled carbon nanotubes decorated with Ni-doped SnO2 nanocrystals

Abstract

In this work, Ni-doped SnO₂@MWCNTs composites were synthesized by a facile one-step hydrothermal method. The morphology and structure of the as-prepared composites were characterized by XRD, SEM, TEM, XPS, FT-IR and Raman. It was found that the SnO₂ nanoparticles were successfully anchored on the MWCNTs with a diameter of 3–5 nm and Ni²⁺ was successfully doped into the SnO₂@MWCNTs. Moreover, the effect of the doped Ni molar percentage on the electromagnetic parameters and microwave absorbing properties of the Ni-doped SnO₂@MWCNTs composites was studied in the 2–18 GHz frequency range. The results showed that the composites with 28.2% doped Ni content exhibited the best microwave absorbing properties. The maximum RL reached −39.2 dB at 8.2 GHz with a thickness of 2.5 mm, and the bandwidth of RL lower than −10 dB was 3.6 GHz (from 12.6 to 16.2 GHz) with a thickness of 1.5 mm. The excellent microwave absorbing properties could be attributed to the good impedance match, Debye relaxation, interfacial polarization and high conductivity of the MWCNTs component. It was believed that the Ni-doped SnO₂@MWCNTs composites could be used as a new type of microwave absorbing materials against electromagnetic pollution.