Nitrogen-doped 3D hollow porous flower-like carbon nanosheets as lightweight high-performance electromagnetic wave absorbers

Three-dimensional porous carbon-based materials have garnered significant attention due to their outstanding structural properties and remarkable microwave absorption capabilities. However, the construction of well-defined 3D carbon material structures currently relies on complex preparation processes and stringent conditions. In this study, hollow nitrogen-doped carbon flowers (HNC) with large specific surface area and multilevel pore structure were successfully prepared by a simple carbonization and etching process. This unique structure not only greatly reduces the material density, but also introduces nitrogen atoms that can generate more dipole polarization, effectively improving impedance matching and enhancing electromagnetic wave absorption performance. Notably, the material exhibits optimal electromagnetic wave absorption at a 25 % fill rate, with a minimum reflection loss (RL min ) of −55.49 dB at a thickness of 3.248 mm and an effective absorption bandwidth of 4.4 GHz. Given its straightforward preparation process, HNC holds the potential to be one of the options for high-performance microwave absorber materials.