Hollow porous Fe2O3 microspheres wrapped by reduced graphene oxides with high-performance microwave absorption
Benefit from the adjustment of the organic ligand, porous Fe2O3 microspheres tightly wrapped by reduced graphene oxide (Fe2O3@RGO) were synthesized via a facile one-step hydrothermal method. Assembly Fe2O3 microspheres with different morphologies and sizes can be effectively regulated by controlling the iron source additions. As-synthesized Fe2O3 spheres gradually changed from solid, hollow to final solid ball with decreasing size from 800 nm to 200 nm. Intrinsic dielectric properties and charge density distribution were characterized by the network analysis (VNA) and off-axis electron holograph. Owing to the unique structure design, better electron transportation behavior and enhanced dielectric and interfacial polarization, RGO wrapping hollow Fe2O3 micorwave spheres exhibit the best electromagnetic energy conversion ability. The maximum reflection loss can reach -48.1dB and the effective absorption bandwidth cover 5.28 GHz (10.48-15.76 GHz) at the 2.5 mm. Turning the thickness from 1 to 5 nm, the strongest reflection loss peaks can shift from high to the low frequency, showing adjusting absorption property.