Achieving enhanced microwave absorption performance based on metal/covalent organic frameworks-derived heterostructures

The high performance “thin, light, wide and strong” pursued by microwave absorbing materials is strongly determined by the structure regulation of materials. Herein, we developed the metal/covalent organic frameworks (MOFs/COFs) heterostructures for enabling multiple interfaces and abundant defect vacancies to enhance impedance matching characteristic and dissipation property. The MOF presents uniform pore distribution, large specific surface area and tunable chemical structures. Furthermore, two kinds of COFs were formed by successively polymerizing based on Schiff-base reaction, and in-situ coated on the MOFs-derived Co/C hybrids to favor rich interfaces. The Co/[email protected] possesses a minimum reflection loss (RLmin) of −48.7 dB at ultrathin thickness of 1.61 mm. In particular, the RLmin of Co/[email protected] is −50.6 dB at 8.8 GHz. Meanwhile, CST simulation was carried out to confirm the microwave absorption capabilities under actual far field conditions. The Radar cross section (RCS) values for Co/[email protected] and Co/[email protected] at 0° scattering angle are reduced to 3.88 dB m2 and -12.23 dB m2 from 7.96 dB m2 (Co/C). It is noted that the RCS values of MOFs/COFs-derived hybrids are less than −10 dB m2 at −90°∼90°. This novel MOFs/COFs open up an avenue for advanced absorbing materials.