Bimagnetic Co_<i>x</i>Ni_{100–<i>x</i>} Nanocrystals Anchored on MoS₂ Nanosheets for Applications as Microwave Absorption Materials

Compositing magnetic materials is a promising strategy to optimize impedance matching and improve microwave absorption of 1-fold MoS2 by synergetic dielectric/magnetic losses. Herein, hierarchical CoxNi100–x/MoS2 microwave absorbents were fabricated through a two-step hydrothermal route, followed by reduction annealing treatment for microwave absorption. Magnetic metallic CoNi nanoparticles/nanoplates were nucleated in situ and grown onto the surfaces and gaps of sheet-assembled MoS2 nanoflowers, which can induce particular magnetic loss and form sufficient Schottky-type heterogeneous interfaces to enhance interfacial polarization and dielectric loss. The 3D hierarchical structure can prolong the propagation paths of microwaves and improve scattering, favoring the boost of microwave dissipation. Benefiting from the improved impedance matching and boosted microwave dissipation capacity, CoNi/MoS2 exhibits enhanced dielectric loss and microwave absorption properties compared to 1-fold MoS2, single CoNi alloy, and their physical mixture. Co50Ni50/MoS2 shows a minimum RL (RLmin) value of −65.6 dB at 17.6 GHz with a small thickness of 1.56 mm, and the effective absorption bandwidth (EAB) is up to 6.0 GHz (10.5–16.5 GHz) at 2.0 mm. CoxNi100–x/MoS2 shows component-regulated electromagnetic properties and microwave absorption performance, which can be adjusted by changing the CoNi/MoS2 component ratio and Co/Ni atomic proportion. Especially, Co70Ni30/MoS2 achieves efficient comprehensive microwave absorption performance at smaller thicknesses: RLmin reaches −55.3 dB at 16.6 GHz with an ultrathin thickness of 1.26 mm, and the EAB is 4.6 GHz (11.7–16.3 GHz) at only 1.5 mm. This work suggests that decorating MoS2 with magnetic metals/alloys is a promising strategy to optimize impedance matching and improve microwave absorption, realizing strong absorption efficiency and a broad effective absorption bandwidth at ultrathin thickness.