EDA-steered in situ staged reduction–etching synthesis of hollow CuxNi1−x/Ni core–shell composites with broad bands and strong microwave absorption

Despite the progress in the synthesis of hollow nanomaterials, the one-pot fabrication of magnetic bimetallic hollow core–shell composites remains a major challenge. Herein, we first reported a novel, simple, and one-pot strategy to facilely prepare CuxNi1−x/Ni core–shell composites, whose morphologies evolve from solid nanorods to hollow microspheres and novel nanotubes in the absence of any surfactant or template. The morphological evolution is related to the selective adsorption of ethylenediamine (EDA) on the Cu (111) surface, which steers the anisotropy growth and the final morphology. The CuxNi1−x/Ni composites have excellent ferromagnetic behavior, and the solid nanorods and hollow microspheres exhibit the largest Ms and Hc, respectively. Here, the wax-based composites containing 22 wt% CuxNi1−x/Ni nanotubes possess remarkably enhanced absorption capability with a maximum absorption of −64.69 dB at 11.97 GHz and an effective bandwidth (90% attenuation) of 5.54 GHz. The superior microwave absorption performance is associated with the cooperation of multiple polarizations, double magnetic resonances, large attenuation, and proper impedance match resulting from the 1D, core–shell, and hollow nanostructures. Our work develops a new strategy with greater value for the construction of bimetallic core–shell hollow structures in electromagnetic wave absorbing materials, catalysis, sensors, as well as microreactors.