Scalable Preparation and Microwave Absorption of Lightweight Fe3O4/Mesoporous Carbon Microsphere Composites

Fe 3 O 4 /mesoporous carbon microspheres (MCMSs) composites were prepared by a facile wet-impregnation method using spray-drying produced MCMSs as carbon substrates.The structure, morphology and microwave absorbing performance were investigated.Results indicate that the composites have good fluidity and low bulk density of 0.24 0.33 g/m 3 .The Fe 3 O 4 nanoparticles are homogeneously dispersed in the mesoporous channels without blocking the porosity of MCMSs.The resulting Fe 3 O 4 /MCMSs composites have very high BET surface areas of 548-735 m 2 /g, which promote multiple relaxations.In the frequency range of 218 GHz, the microwave loss is primarily derived from dielectric loss.The composite with 40wt% Fe 3 O 4 exhibits a maximum reflection loss of -25 dB at 12.6 GHz and a broad absorption band over 4.7 GHz.Such good microwave electromagnetic performances can be ascribed to the synergistic effects of highly dispersed Fe 3 O 4 nanoparticles and mesoporous channels, which can increase interfacial relaxation and microwave diffraction as well as reduce the reflection of microwave at the interface between air and absorber.