The synthesis of three-dimensional (3D) polydopamine-functioned carbonyl iron powder@polypyrrole (CIP@PPy) aerogel composites for excellent microwave absorption

• Novel 3D CIP@PPy aerogel composites were synthesized.
• Dopamine was used as intermediary to connect CIPs with PPy.
• Flaky carbonyl iron powder enhance internal multiple reflections.
• Two strong absorption peaks are −38.9 and −39.5 dB, the bandwidth is 6.1 GHz.
• Interfacial polarization and geometry effect are the crucial mechanisms.

Novel 3D CIP@PPy aerogel composites were synthesized through a self-assembled polymerization method using dopamine as intermediary. The 3D CIP@PPy aerogel composites were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FTIR). The absorption properties were investigated by a vector network analyzer (VNA) in the frequency range of 2–18 GHz. For the CIP@PPy 33 wt% aerogel, the RLs show two strong absorption peaks values of −38.9 and −39.5 dB at 12.2 GHz and 14.2 GHz under the thickness of 2.2 mm, respectively, and the bandwidth can reach 6.1 GHz. The CIP@PPy aerogel composites would be a promising candidate as microwave absorption materials (MAMs) with strong absorption, wide frequency band and lightweight. The improvement of microwave absorbing properties can be attributed to interfacial polarization and geometry effect.