Hollow porous Fe2O3 microspheres wrapped by reduced graphene oxides with high-performance microwave absorption

Abstract

Benefiting from the assistance of an organic ligand, porous Fe₂O₃ microspheres tightly wrapped by reduced graphene oxides (Fe₂O₃@RGO) were synthesized via a facile one-step hydrothermal method. The assembled Fe₂O₃ microspheres with different morphologies and sizes can be effectively regulated by controlling the addition of the iron source. The as-synthesized Fe₂O₃ spheres gradually changed from solid, hollow to a final solid ball with decreasing sizes from 800 nm to 200 nm. Intrinsic dielectric properties and charge density distribution were characterized by vector network analysis (VNA) and off-axis electron holography. Owing to their unique structure design, better electron transport behavior and enhanced dielectric and interfacial polarization, RGO wrapped hollow Fe₂O₃ microspheres exhibit the best electromagnetic energy conversion ability. The maximum reflection loss can reach −48.1 dB and the effective absorption bandwidth cover is 5.28 GHz (10.48–15.76 GHz) at 2.5 mm. Tuning the thickness from 1 to 5 nm, the strongest reflection loss peaks can shift from high to low frequency, showing adjusting absorption properties.