SiO2 Nanosphere-Decorated NiS2/Ni3S4 Hierarchical Microspheres for Enhanced Microwave Attenuation

Abstract

Dielectric constant modulation and heterointerface engineering are considered efficacious strategies to construct high-performance electromagnetic wave (EMW) absorption. Herein, a series of dual-phase nickel sulfide (NiS2/Ni3S4) hierarchical microspheres decorated with diverse contents of silicon dioxide (SiO2) nanospheres have been successfully synthesized via the Stöber method and subsequent solvothermal process. Profiting from the rational dielectric constant regulation, the NiS2/Ni3S4/SiO2-1 composites achieve an optimal RL value of −66.6 dB at 2.09 mm and the broadest effective absorption bandwidth (EAB) of 6.28 GHz at 2.18 mm within a filler loading of 20 wt %, far superior to that of pure NiS2/Ni3S4 composites. When the content of absorber increases to 25 wt %, the microwave absorption properties of NiS2/Ni3S4/SiO2-1 composites are the utmost, further verifying the importance of a reasonable addition amount of SiO2 nanospheres. It is concluded that the introduction of SiO2 nanospheres can not only expand the heterogeneous interface but also improve impedance matching by regulating the dielectric constant. Furthermore, the results of radar cross section (RCS) simulation demonstrate the dissipative capability for radar signals in practical applications. The findings furnish a viable pathway for exploring broadband microwave-absorbing materials.