Superior and highly absorbed electromagnetic interference shielding performance achieved by designing the reflection-absorption-integrated shielding compartment with conductive wall and lossy core

Conductive polymer composites with high conductivity possess high electromagnetic interference shielding effectiveness (EMI SE), which is however associated with the complication of excessive reflectivity to cause secondary pollution. In this regard, we designed a micro shielding unit, named reflection-absorption-integrated shielding compartment, which was composed of magnetic hybrids uniformly distributed inside and the CNT walls wrapped outside. Magnetic hybrids were synthesized by depositing Fe3O4 nanoparticles on the surface of reduced GO (rGO@Fe3O4, RGF) and were uniformly dispersed in polycarbonate (PC) microspheres. Then, CNTs were wrapped onto these microspheres to obtain reflection-absorption-integrated shielding compartments. Exhilaratingly, the macroscopical shielding composites by assembling these compartments displayed not only superior EMI shielding performance, but also enhanced EM absorption ability. An EMI SE of 43.5 dB and a SEA/SET ratio of similar to 90% were acquired for the composite constructed by 4 wt% CNT/5 wt% RGF compartments. It was attributed to the synergistic effect of CNT walls and RGF hybrids to capture and attenuate EM waves. The outer CNT walls acted as reflectors to generate multiple reflections and the inner RGF hybrids with both dielectric and magnetic loss served as absorbing units. This design concept is of practical significance for fabrication of high-performance shielding composites to meet stringent shielding and absorption requirements.