“Tree blossom” Ni/NC/C composites as high-efficiency microwave absorbents

Abstract

Precursors of a nickel-based metal–organic framework, denoted Ni-MOF, and the loofah plant were prepared by the microwave method, and “tree blossom” Ni/Nitrogen doped Carbon (NC)/ Carbon (C) composites were prepared by in situ pyrolysis under an argon atmosphere. During pyrolysis, the morphology, specific surface area, porous structure and electromagnetic parameters of the Ni/NC/C composites were adjusted by adjusting the pyrolysis temperature. The maximum reflection loss of the corresponding Ni/NC/C composites can reach −63.1 dB at 13.84 GHz and a thickness of 2 mm when the pyrolysis temperature was 650 ℃ and the filling amount was 16 wt%. And the effective absorption bandwidth was 35.44 GHz when the thickness was adjusted from 1 mm to 5.5 mm within the range of 2–40 GHz. Excellent performance comes from conduction loss, dipole and interface polarization, magnetic resonance, multiple electromagnetic reflections and scattering, and equilibrium impedance matching.