Ti-MOF@Metal-polyphenol network derived TiN0.9@NC/magnetic MWCNTs composites for microwave absorption

Magnetic carbon-based microwave absorption materials (MAMs) derived from metal-organic frameworks (MOFs) have been regarded as promising candidates for addressing the electromagnetic pollution. The construction of magnetic carbon-based MAMs derived from MOFs with ferromagnetic centers (Fe, Co, Ni etc.) and their composites has become a mainstream in recent years. However, MOFs with non-magnetic centers have received less attentions due to the challenges in achieving magnetic-dielectric synergistic effect and proper impedance matching in their derivatives. In this work, a facile metal-polyphenol network coating strategy has been proposed to facilitate the construction of magnetic MWCNTs decorated TiN0.9/NC absorber derived from non-magnetic MIL-125(Ti). The regulation effect of carbothermal temperature on magnetism, defect density, graphitization degree as well as electromagnetic parameters of absorbers have been systematically investigated. The obtained composites exhibit outstanding microwave absorption performance due to the magnetic-dielectric synergistic effect and improved impedance matching. The minimum reflection loss reaches -42.55 dB at 1.91 mm and the effective absorption bandwidth reaches as wide as 4.6 GHz with an ultra-thin thickness of only 1.38 mm. It is believed that this study provides a new way to construct efficient magnetic carbon-based MAMs with non-magnetic metal-based MOFs and a meaningful exploration for the preparation of ultra-thin absorbers.