Design and synthesis of NiCo/CoS@C hybrid material with tunable and efficient electromagnetic absorption.

Producing electromagnetic wave absorbers with high absorption capacity and wide absorption bandwidth is still a challenge task, which limits its application in human life. In this study, a novel carbon-coated NiCo alloy/CoS hybrid material was fabricated by a simple strategy. By adjusting the annealing temperature, the electromagnetic wave absorption property of NiCo/CoS@C hybrid material can be further improved. Herein, the NiCo/CoS@C hybrid material obtained at 750 °C exhibits satisfactory electromagnetic wave absorption performance. The minimum reflection loss value of -56.96 dB is obtained at 10.32 GHz, and the matching thickness is only 2.71 mm. When the thickness of the absorber is in the range of 1.8-5.0 mm, the effective absorption bandwidth is controlled between 4.64 and 18 GHz. The satisfactory properties of the hybrid materials are attributed to the space charge polarization caused by heterogeneous NiCo alloys, interfacial polarization between components and good impedance matching characteristics. The results show that NiCo/CoS@C hybrid material is a potential electromagnetic wave absorber.