Design and fabrication of a hollow nanobowl-like heterostructured PPy@Co/CoFe2O4@HNBC composite as a remarkable electromagnetic wave absorber

A heterostructured polypyrrole@magnetic Co/CoFe 2 O 4 nanoparticles@hollow nanobowl-like carbon (PPy@Co/CoFe 2 O 4 @HNBC) composite with a layer-by-layer (LBL) structure based on HNBC was prepared via a facile three-step process. HNBC was synthesized by a typical template method, then sequentially decorated with Co/CoFe 2 O 4 and PPy via in-situ growth and polymerization. The relationship between the structure, components, and electromagnetic wave (EMW) absorption performance of PPy@Co/CoFe 2 O 4 @HNBC was studied in depth. The EMW absorbing research shows that PPy@Co/CoFe 2 O 4 @HNBC exhibits excellent EMW absorption capability, with a minimum reflection loss (RL min ) of up to −61.85 dB at 12.80 GHz and 1.90 mm and a widest effective absorption bandwidth (WEAB, RL≤−10.00 dB) value of 5.60 GHz at 1.70 mm. The excellent EMW absorption performance of PPy@Co/CoFe 2 O 4 @HNBC can be ascribed to the multiple reflection and scattering that occurs due to its unique microstructure and the synergistic effects between the polarization and conduction induced dielectric loss , and the natural resonance and exchange resonance induced magnetic loss. As a consequence, the PPy@Co/CoFe 2 O 4 @HNBC composite designed in this work is a hopeful candidate for application in the field of EMW absorption.