Facile fabrication of carbon microspheres decorated with B(OH)₃ and α-Fe₂O₃ nanoparticles: Superior microwave absorption

We demonstrate that novel three-dimensional (3D) B(OH)₃ and α-Fe₂O₃ nanoparticles decorated carbon microspheres (B(OH)₃/α-Fe₂O₃-CMSs) can be fabricated via a facile thermal treatment process. The carbon microspheres with diameter of 1–3 μm and decorated B(OH)₃ and α-Fe₂O₃ nanoparticles with diameters of several to tens of nanometers are successfully fabricated. These novel 3D B(OH)₃/α-Fe₂O₃-CMS composites exhibit enhanced microwave absorption with tunable strong absorption wavebands in the frequency range of 2–18 GHz. They have a minimum reflection loss (RL) value of −52.69 dB at a thickness of 3.0 mm, and the effective absorption bandwidth for RL less than −10 dB is as large as 5.64 GHz. The enhanced microwave absorption performance arises from the synergy of the impedance matching caused by the B(OH)₃ nanoparticles, dielectric loss as well as the enhancement of multiple reflection among 3D α-Fe₂O₃ nanocrystals. These results provide a new strategy to tune electromagnetic properties and enhance the capacity of high-efficient microwave absorbers.