Hollow polyaniline derived N/S co-doped carbon nanoflakes with modulated polarization behavior for enhanced microwave absorption property

Anion-doped induced vacancy engineering is an effective approach to modulate polarization behavior and enhance the microwave absorption property. Herein, bamboo leaf-like polyaniline-mediated nitrogen and sulfur co-doped carbon (N/S–B–C) nanoflakes were demonstrated and successfully prepared by in-situ polymerization method and carbonization process with oxygen limitation. The hollow N/S–B–C nanoflakes are decorated by orderly aligned nanorods on the surface, which effectively balances the intrinsic high conductivity and strong polarization behavior of carbon material. The substitution of heterogeneous atoms disrupts the symmetry of local microstructures, leading to the dipolar resonances and/or vibration for enhancing dielectric loss. The N/S–B–C nanoflakes possess the minimum reflection loss (RL_min) of − 53.5 dB at 10.2 GHz and corresponding effective absorption band (EAB) of 4.5 GHz at 2.9 mm. When the thickness is only 2.22 mm, the widest EAB is up to 5.15 GHz ranging from 12.30 to 17.40 GHz. This outstanding conductivity loss and interfacial polarization relaxation as well as the improved impedance matching from hollow structure synergistically determine excellent microwave absorption performance. This study provides an effective strategy for exploring the underlying relations between conduction loss and polarization behaviors in graphitized carbon.