Confined magnetic nickel nanoparticles in carbon microspheres with high-performance electromagnetic wave absorption in Ku-band

Composition and structure regulation is the primary strategy in preparing high-performance electromagnetic (EM) wave absorption materials. Herein, magnetic-dielectric synergy Ni@C microspheres were fabricated to obtain the high-performance electromagnetic (EM) wave absorption performance. Firstly, the Ni-containing precursor microspheres were obtained via the spray-drying technology. Secondly, reduced magnetic Ni nanoparticles (NPs) were confined in the N-doped carbon microspheres after pyrolysis treatment in the H-2/Ar atmosphere. Duo to the existence of melamine, the distribution of Ni NPs and related EM parameters of Ni@C microspheres were efficiently regulated to seek the well impedance matching and EM responded ability. As results, as-synthesized Ni@C microspheres exhibited the minimum reflection loss (RLmin) of -48.2 dB and effective absorption bandwidth (EAB) of 5.7 GHz, covering almost Ku-band. This research represents a significant advancement in the development of magnetic-dielectric composite microspheres with superior absorption capacity, and it also provides a large-scale preparation strategy for electromagnetic wave absorbing materials.