Binary metal ions modulating MOF-derived sponge-structured nanocomposites for controlled electromagnetic wave absorption from S-band to Ku-band

5G communication is developing vigorously, but the microwave absorption in the 2-8 GHz lower-frequency region is still challenging. In this work, 3D carbon nano-sponges (NiZn/C) embedded with magnetic Ni and dielectric Ni3ZnC0.7 was synthesized by direct co-assembly of binary metal ions with a ligand hexamethylene-tetramine followed a calcination process. The charge distribution, proportion, and interface/dipole polarization of dielectric/magnetic materials can be adjusted. Most strikingly, NiZn/C-7 exhibits extensively upgraded electromagnetic wave absorbing (EMWA) performance from S-band to Ku-band. The minimum reflection loss (RLmin) value of-52.5 dB occurs in the C-band at 5.1 GHz with a thin layer of 3.95 mm. A strong attenuation with RLmin value of -33.7 dB is obtained at 3.9 GHz (S-band) with the thickness of 5.00 mm. The EAB reaches 4.08 GHz at a skinny thickness of 1.44 mm. This work provides a simple preparing high-performance microwave absorbing materials to address the EM pollution yielded by 5G signals.