Microwave-based synthesis of (NiCo)x/(MnO)y/C composites and their tunable wave absorption properties in the K band.

The combination of metallic and carbon components offers tremendous advantages in the development of advanced composites for electromagnetic wave absorption (EMWA) applications. Herein, hollow (NiCo) x /(MnO) y /C microspheres (MSs) possessing hierarchically porous structures were successfully synthesized via a facile microwave-assisted method followed by a carbonization step. The EMWA performance of the (NiCo) x /(MnO) y /C MSs in the K-band region could be tuned and optimized by adjusting the NiCo/Mn molar ratio, with a NiCo/Mn ratio of 1:1 affording the best EMWA performance. The NiCo/MnO/C MSs exhibited a minimum reflection loss value of -32.3 dB (at 21.4 GHz) and an effective absorption bandwidth (EAB, RL ≤ −10 dB) of 8.33 GHz (from 18.17-26.5 GHz) at a thickness of only 1.0 mm in the K band. The excellent EMWA performance of the (NiCo) x /(MnO) y /C MSs composites can be attributed to a strong EMW attenuation capacity and good impedance matching, which arise through the synergistic action of the components (NiCo alloy, MnO and C) and hierarchical pores. Image 1 [ABSTRACT FROM AUTHOR]