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Optimization, selective and efficient production of CNTs/CoxFe3−xO4 core/shell nanocomposites as outstanding microwave absorbers

It is well-known that suitable optimization of electromagnetic parameters is a feature to achieve outstanding electromagnetic wave absorption performances (EMWAPs). Accordingly, an effective way to develop high-performance microwave absorbers is to construct dielectric–magnetic core/shell structure nanocomposites with a controllable microstructure and composition parameters. Herein, we propose a simple route to synthesize core/shell structure nanocomposites consisting of carbon nanotubes (CNTs) as the core and magnetic nanoparticles as the shell via a one-step hydrothermal method. By adjusting the experimental parameters, core/shell structure CNTs/CoxFe3−xO4 nanocomposites with different morphologies, contents of CNTs, Co : Fe molar ratios and types of CNTs were selectively synthesized. Also, the electromagnetic properties and EMWAPs of the obtained samples were highly dependent on their microstructure and composition parameters. Thus, by optimizing these parameters, the designed nanocomposites simultaneously exhibited very small values of minimum reflection loss and broad absorption bandwidth with very thin matching thicknesses. Additionally, the outstanding comprehensive EMWAPs of samples were proven to be attributed to their improved impedance matching, attenuation loss characteristics, dielectric loss abilities and excellent synergetic effect. Generally, considering the simple process, environment-friendly, low cost, controllable production and high stability of the nanocomposites, our findings provide an effective way to optimize electromagnetic properties and design high-performance microwave absorbers.