FeNi/C/TiO2 composites derived from [Fe(pz)Ni(CN)4] Hofmann framework and MXene for efficient electromagnetic absorption

Chemical composition and morphological optimization are both effective strategies for constructing excellent electromagnetic wave absorption (EMWA) materials. While efficient EMWA materials derived from both metal-organic frameworks (MOFs) and MXenes have been extensively studied, composites derived from the Hofmann framework with MXene have not been reported. In this study, we employed a Hofmann framework ([Fe(pz)Ni (CN)4], pz = pyrazine) and MXene (Ti3C2Tx) to create new MXene@Hofmann (MH1 and MH2) composites, using a simple co-precipitation method with two different contents of [Fe(pz)Ni(CN)4]. The FeNi/C/TiO2 composites with a multi-layered structure inherited from MXene were prepared by annealing the MXene@Hofmann com-posites at 500, 600, and 700 degrees C, resulting in the formation of MH1-500/600/700 and MH2-500/600/700 composites. Their compositions, morphologies, electromagnetic parameters, and EMWA performances were characterized. For the composites with a high [Fe(pz)Ni(CN)4] content, MH2-600 has a minimum reflection loss (RLmin) value of-30.63 dB at a thickness of only 1.8 mm and the broadest effective absorption bandwidth (EAB) of 3.90 GHz at 2.0 mm, while MH2-700 exhibits superior EMWA performance with an RLmin value of-34.34 dB at 1.9 mm and an EAB value of 4.96 GHz at 2.1 mm. Their impressive EMWA performance might be attributed to the synergistic dielectric loss and magnetic loss and also the impedance matching from the reasonable ratio of the magnetic and dielectric components. This work demonstrates an effective strategy for constructing EMWA materials from the Hofmann framework and MXene.