3D flower-shape Co/Cu bimetallic nanocomposites with excellent wideband electromagnetic microwave absorption

Electromagnetic wave (EMW) absorbing materials prepared by Metal-organic-frameworks (MOFs) derived two-dimensional sheet carbon materials and magnetic metal composites have been widely studied because of their advantages of low density and large specific surface area. However, it is still a challenge to design the micro-structure and composition of materials effectively to obtain the best EMW absorption properties. In this work, 3D flower-shape Co/Cu bimetallic nanocomposites were synthesized by calcination of MOFs precursors. By tuning the ratio of Co and Cu salts, nanocomposites with different morphology, size and pore structure were obtained. Impedance matching can be improved by adjusting the synergistic effect of magnetic loss and dielectric loss. When the molar ratio of Co and Cu salts was 4:1, the best EMW absorption performance of the CoCu-CNF-10 composite was achieved. The minimum reflection loss reaches -51.7 dB at 12.6 GHz with a thin thickness of 2.7 mm, while the effective absorption bandwidth is as broad as 6.4 GHz (9.7-16.1 GHz). This work provides a new idea for the rational design of MOFs-derived materials with excellent EMW absorption properties.