Tailored ternary hetero-interfaces with in situ formed CNTs for effective electromagnetic coupling at low/mid-frequency

With the rapid development of 5G wireless communication technology, the main working ranges of civilian fields are gradually concentrating at low-frequency; however, ternary component modulation engineering, which can optimize the decoupling effect between impedance matching and strong attenuation capability at low-frequency, remains challenging. Herein, Co/MnO@NC-X with tailored ternary hetero-interfaces was prepared by the solvothermal method and subsequent high-temperature pyrolysis, and the modulation of the absorption band was achieved by adjusting the doping ratio of melamine. The minimum reflection loss (RLmin) value of the Co/MnO@NC-3 nanocomposite reaches −41.19 dB at low-frequency (3.6 GHz). The RLmin value of the Co/MnO@NC-5 nanocomposite is −40.6 dB at low-frequency (6.0 GHz) and −47.4 dB at mid-frequency (8.8 GHz). In addition, more than 90% of the electromagnetic waves (EMWs) can be absorbed in the 2–18 GHz range by adjusting the thickness of the composites (1.0–5.5 mm). The prominent performance results from the synergy between the magnetic/dielectric/conductive triad. Cobalt provides magnetic loss and effectively catalyzes the in situ growth of CNTs, which construct a conductive network to promote the conductive loss and regulate the impedance matching, while MnO regulates the dielectric loss. Low-frequency absorption is achieved by building a reasonable structure and controlling the degree of graphitization to maximize the attenuation constant while ensuring impedance matching. This strategy provides a simple argument for the development of high-efficiency low/mid-frequency EMW absorbing materials with ternary components.