Enhance the electromagnetic absorption performance of Co&Ni@GNs by designing appropriate cCo: cNi deposited on GNs surface

In this work, by using synthetic innovation and improved one-step hydrothermal method to deposit Co&Ni alloy on graphite nanosheets (GNs), Co&Ni@GNs with more stable absorbing performance was successfully prepared. Compared to Hummers process of GNs, the advantage of this work is is that the process of acidifying GNs is simple. Co&Ni@GNs exhibit tightly connected interfaces, this may contribute to interfacial polarization and defect dipole polarization, so EM (electromagnetic) waves absorption performance can be improved by increasing dielectric loss. The strong dielectric relaxation can be observed in Co-Ni@GNs-2 (cCo:cNi=3:2) samples, which further enhances the dielectric loss. The minimum reflection loss of Co-Ni@GNs-2 is -47.26 dB at 2.6 mm, and the effective absorption bandwidth is 3.72 GHz at 1.7 mm. At the 2–18 GHz, the Z_in/Z₀ value of Co-Ni@GNs-2 is closer to 1, indicating that EM waves is easier to enter the composite and has a higher attenuation constant. The modified one-step hydrothermal method is low-cost and shorter time, which could become an industrial technique to synthesize carbonaceous composites for electromagnetic absorption.