Preparation And Microwave Absorption Properties Of Cobalt-based MOF-derived Carbon-based Composites

Nowadays,electromagnetic radiation pollution has posed serious threats on electronic equipment and human health.To address these problems,researchers are committed to the design and preparation of efficient microwave absorbing materials so as to solve the increasingly serious problems of electromagnetic pollution.Thus,robust and thin microwave absorbers with wide range and lightweight have been proposed.To date,carbon materials derived from metal-organic framework?MOF?show great potentials in the design of composition and structure,and attract people's attention in terms of efficient microwave absorption.Herein,the lightweight Co-MOF?ZIF-67?derivative Co/NC was integrated with Ni and MoS₂.Based on the design of composition and structure,the impedance matching of the composites were optimized to overcome the disadvantages of poor impedance matching of Co/NC.The main results are as follows:?1?Via further pyrolysis,Ni/Co/NC composites with different morphology and magnetic composition were prepared using Co-MOF as precursor based on ion exchange and etching in solution at room temperature.When the filling ratio of absorber in paraffin is 20wt%,the minimum reflection absorption of Ni/Co/NC-0.8 complex can reach-34 dB at 17.2 GHz with the thinner thickness of 1.8 mm.However,the best reflection loss for Ni/Co/NC-1.2with the matching thickness of 2.2 mm at 14.1 GHz is-64 dB,and the effective absorption bandwidth?RL?-10 dB?is 6.4 GHz?11.5-17.9 GHz?.?2?Co/NC was obtained by pyrolysis of Co-MOF,flake MoS₂ was grown on the surface of Co/NC via hydrothermal method.During the hydrothermal reaction,Co nanoparticles were vulcanized to obtain CoS_x/NC@MoS₂ composites with different proportions of core-shell structure.The incorporation of metal sulfides improved the dielectric relaxation of the materials.When the mass ratio of Co/NC and MoS₂ is 1:1,the microwave absorption performance of the composite was the best.When the amount of absorber is 40 wt%,the optimized reflection loss of-54.4 dB and the effective absorption bandwidth is 3.4 GHz?14.6-18 GHz?when the thinner thickness is 1.36 mm.