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

NiMZn/C@MSDC (M=Co, Fe, Mn, MSDC represents melamine sponge-derived carbon) composites were prepared by the vacuum pumping solution method followed by carbonization process. A large number of carbon nanotubes (CNTs) were homogeneously attached to the surfaces of the 3D cross-linked of the sponge-derived carbon in the NiCoZn/C@MSDC composite, while CNTs can not be detected in NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. Besides the existence of Ni3ZnC0.7, Ni3Fe and MnO in-situ formed in NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. The generated CNTs in NiCoZn/C@MSDC composite efficiently tuned the complex permittivity and thus showed the best microwave absorption performances. The NiCoZn/C@MSDC composite exhibits a RLmin value of -33.1 dB at 18 GHz at a thickness of 1.4 mm. The bandwidth for RL≤-10 dB is up to 5.04 GHz at a thickness of 1.7 mm with a low loading of 25 wt%. The optimized impedance matching, enhanced interfacial and dipole polarization, remarkable conduction loss and multiple reflections and scattering of the incident microwaves improve the microwave absorption performances. The substitution effects of Co, Ni and Fe on the phase and morphology changes provide an alternative way to develop highly efficient and broadband microwave absorbers.