Structural engineering of porous biochar loaded with ferromagnetic/anti-ferromagnetic NiCo 2 O 4 /CoO for excellent electromagnetic dissipation with flexible and self-cleaning properties

Design of multi-functional microwave absorption materials with strong dissipation ability is a practical approach to address the current issue of electromagnetic radiation pollution. Herein, based on the exchange bias interaction between ferromagnetic and anti-ferromagnetic interfaces, a series of absorbers composed of the porous biochar loaded with ferromagnetic/anti-ferromagnetic NiCo 2 O 4 /CoO were successfully prepared via a fairly simple process of one-step calcination. By regulating the calcination temperature, the pore size and porosity of porous carbon, morphology of loaded NPs as well as the electromagnetic response property and impedance matching characteristic in such composites can be modulated. The porous biochar/NiCo 2 O 4 /CoO composite prepared under 350 degrees C possesses a remarkable electromagnetic absorption reflection loss (RL) of -48.41 dB at 9.12 GHz with 2.5 mm thickness, and the effective absorption bandwidth (EAB) of 4.32 GHz with 2.2 mm thickness is located at X band, this is owing to the strong coupling effect of multiple dielectric polarizations, magnetic resonances, and eddy current consumption under matched impedance. In addition, the microwave absorbing patch prepared with this composite exhibits a well-hydrophobic property for self-cleaning function, and the large extensibility with substantial breaking strength endows its practical usage as a flexible absorber. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.