NiCoZn/C@melamine sponge-derived carbon composites with high-performance electromagnetic wave absorption

NiMZn/C@melamine sponge-derived carbon (MSDC) composites (M = Co, Fe, and Mn) were prepared by a vacuum pumping solution method followed by carbonization. A large number of carbon nanotubes (CNTs) homogeneously attached to the surfaces of the three-dimensional cross-linked of the sponge-derived carbon in the NiCoZn/C@MSDC composite, and CNTs were detected in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. Ni₃ZnC_0.7, Ni₃Fe, and MnO in-situ formed in the NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. The CNTs in the NiCoZn/C@MSDC composite efficiently modulated its complex permittivity. Thus, the composite exhibited the best performance among the composites, with the minimum reflection loss (RL_min) of −33.1 dB at 18 GHz and thickness of 1.4 mm. The bandwidth for RL of ≤−10 dB was up to 5.04 GHz at the thickness of 1.7 mm and loading of 25wt%. The optimized impedance matching, enhanced interfacial and dipole polarization, remarkable conduction loss, and multiple reflections and scattering of the incident microwaves improved the microwave absorption performance. The effects of Co, Ni, and Fe on the phase and morphology provided an alternative way for developing highly efficient and broadband microwave absorbers.