In situ growth of CoNi bimetallic alloys inside polyetheretherketone-derived hierarchical porous carbon as a broadband and efficient electromagnetic wave absorber

Both morphological structure and chemical composition are the important factors that determine the electromagnetic wave (EMW) absorption properties of EMW absorbers. Herein, hierarchical porous carbon (HPPC) was synthesized by using polyetheretherketone (PEEK) as the starting material via the salt template method combined with KOH activation. Then, taking advantage of the hierarchical porous characteristics of the carbon, a novel EMW absorber (HPPC/CoNi) was synthesized by in situ growth of CoNi bimetallic alloys inside the above porous carbon. The as-synthesized HPPC/CoNi exhibits excellent EMW absorption performance with a minimum reflection loss (RLmin) value of -65.56 dB at 2.00 mm and a maximum effective absorption bandwidth (EAB) of 5.92 GHz at 1.80 mm. The superior EMW absorption property is ascribable to the multiple reflection/scattering induced by the hierarchical porous structure of HPPC, dielectric loss, magnetic loss, and good impedance matching. The results show that HPPC/CoNi is a potential EMW absorber with characteristics of ultra-light weight, ultrathin thickness, broad bandwidth, and strong absorption.