Fe/N-Codoped Hollow Carbonaceous Nanospheres Anchored on Reduced Graphene Oxide for Microwave Absorption

To alleviate and even eliminate electromagnetic pollution problems, it is inevitable to evolve materials that exhibit a desirable effect on attenuating microwaves with broad response frequency bandwidth and high absorption capacity, while thickness and weight are equally important. The combination of Fe/N-codoped carbon-based nanospheres (0 dimension) and graphene (2 dimension) are highly desirable for improving microwave absorption properties due to producing advantages between different portions. Herein, hollow Fe3O4 nanoparticles were selected as a hard template; through oxidation polymerization and high temperature carbonization processes in inert atmosphere, the designed structure, Fe/N-codoped hollow carbonaceous nanospheres, was anchored on the surface of reduced graphene oxide. As expected, the lightweight designed nanocomposites exhibited enhanced microwave absorption properties due to increased polarization loss (interfacial and dipole polarization), conductivity loss, and multiple resonance behaviors, with the minimum value of reflection loss achieved as -49.08 dB at 7.15 GHz, while the thickness is 2.5 mm, and the filler ratio is only 5%. In addition, the effective absorption bandwidth can be tuned from 3.1 to 18 GHz, validating them as promising next-generation microwave absorbing materials during practical application.