Bimagnetic Co<sub><i>x</i></sub>Ni<sub>100–<i>x</i></sub> Nanocrystals Anchored on MoS<sub>2</sub> Nanosheets\nfor Applications as Microwave Absorption Materials

Compositing magnetic materials is a promising strategy\nto optimize\nimpedance matching and improve microwave absorption of 1-fold MoS<sub>2</sub> by synergetic dielectric/magnetic losses. Herein, hierarchical\nCo<sub><i>x</i></sub>Ni<sub>100–<i>x</i></sub>/MoS<sub>2</sub> microwave absorbents were fabricated through\na two-step hydrothermal route, followed by reduction annealing treatment\nfor microwave absorption. Magnetic metallic CoNi nanoparticles/nanoplates\nwere nucleated in situ and grown onto the surfaces and gaps of sheet-assembled\nMoS<sub>2</sub> nanoflowers, which can induce particular magnetic\nloss and form sufficient Schottky-type heterogeneous interfaces to\nenhance interfacial polarization and dielectric loss. The 3D hierarchical\nstructure can prolong the propagation paths of microwaves and improve\nscattering, favoring the boost of microwave dissipation. Benefiting\nfrom the improved impedance matching and boosted microwave dissipation\ncapacity, CoNi/MoS<sub>2</sub> exhibits enhanced dielectric loss and\nmicrowave absorption properties compared to 1-fold MoS<sub>2</sub>, single CoNi alloy, and their physical mixture. Co<sub>50</sub>Ni<sub>50</sub>/MoS<sub>2</sub> shows a minimum RL (RL<sub>min</sub>) value\nof −65.6 dB at 17.6 GHz with a small thickness of 1.56 mm,\nand the effective absorption bandwidth (EAB) is up to 6.0 GHz (10.5–16.5\nGHz) at 2.0 mm. Co<sub><i>x</i></sub>Ni<sub>100–<i>x</i></sub>/MoS<sub>2</sub> shows component-regulated electromagnetic\nproperties and microwave absorption performance, which can be adjusted\nby changing the CoNi/MoS<sub>2</sub> component ratio and Co/Ni atomic\nproportion. Especially, Co<sub>70</sub>Ni<sub>30</sub>/MoS<sub>2</sub> achieves efficient comprehensive microwave absorption performance\nat smaller thicknesses: RL<sub>min</sub> reaches −55.3 dB at\n16.6 GHz with an ultrathin thickness of 1.26 mm, and the EAB is 4.6\nGHz (11.7–16.3 GHz) at only 1.5 mm. This work suggests that\ndecorating MoS<sub>2</sub> with magnetic metals/alloys is a promising\nstrategy to optimize impedance matching and improve microwave absorption,\nrealizing strong absorption efficiency and a broad effective absorption\nbandwidth at ultrathin thickness.