Facile synthesis of ZIF-67 derived dodecahedral C/NiCO2S4 with broadband microwave absorption performance

The increasing hazard of electromagnetic radiation prompts people to pursue absorbing materials with better performance. However, absorbing materials with a single loss mechanism usually is unable to obtain better absorbing performance due to low impedance matching or high filling ratio. Therefore, this work proposes a C/NiCo2S4 (CNCS) material with both dielectric loss/magnetic loss to achieve efficient absorption of electromagnetic waves. The simple preparation of CNCS materials was achieved through the etching of the ZIF-67 template by nickel nitrate and the subsequent hydrothermal vulcanization process. Its unique prismatic dodecahedron hollow structure promotes multiple scattering of electromagnetic waves. The attachment of the magnetic NiCo2S4 particles on the surface of the carbon template further promotes the interface polarization and dipole polarization, which is equivalent to the formation of a resistance-rich microcircuit and enhances the effect of the conductance loss on electromagnetic waves. At 2-18 GHz, the CNCS-2 with 30% paraffin addition achieves an effective bandwidth of 5.54 GHz at a matching thickness of 1.7 mm, and has a maximum reflection loss of -36.44 dB at 1.5 mm. By adjusting the thickness of the material matching layer (1-3 mm), an effective bandwidth of up to 13.48 GHz can be achieved, perfectly covering the X-band and Ku-band. Based on the simple preparation process of the material, the special hollow structure and the multiple loss mechanisms for electromagnetic waves, we believe that CNCS can become a strong competitor for high-efficiency broadband absorbers.