Systematic fabrication and electromagnetic performance of porous biomass carbon/ferrite nanocomposites

Biomass carbon is a potential alternate for commercially expensive graphene and carbon nanotubes to fabricate nanocomposites as electromagnetic (EM) wave absorbers. Here, we systematically prepared porous biomass carbon/ferrite nanocomposites with different chemical compositions, particle sizes, and structures using rice husk ash, carbonized luffa sponge, carbonized kapok and cotton fibers. All the prepared nanocomposites show limited dielectric losses, indicating the permittivity is less affected by the micro-morphologies, chemical compositions, and structures of biomass carbon. The magnetic loss of microwaves by most samples is caused by eddy current effect. Both smaller and wider range sized particles would contribute additional natural resonance for the magnetic loss of ferrite nanoparticles. The EM wave absorption performance of the nanocomposites are controlled by both the impedance matching between the absorber and air and their magnetic/dielectric losses for incident EM waves. The maximum bandwidth of RL< −10 dB of the as-prepared nanocomposites is about 4.8 GHz, covering most of the Ku-band. Due to their low density and good impedance matching with air, the biomass carbon/ferrite nanocomposites could be promising green light-weight EM wave absorbers by adjusting the particle sizes of ferrite nanoparticles.