▎ 摘　　要

High-performance electromagnetic shielding materials are highly desired due to the radiation and interference problems of electronic equipment. In this work, a flexible graphene/multi-walled carbon nanotubes (MWCNTs)/ Polydimethylsiloxane (PDMS) electromagnetic shielding composite is fabricated with 3D graphene/MWCNTs foam as electrical conductive skeleton. The structure and composition evolution of foams are studied during the carbonization process from 1200 to 1600 degrees C and the graphitization of ultra-high temperature (2800 degrees C). With the removal of functional groups, the repair of defects enhances the ohmic loss while the polarization loss is reduced. An optimal electromagnetic interference shielding effectiveness (EMI SE)is found with an EMI SE of 54.43 dB at 1400 degrees C. Moreover, compared to pure PDMS, the thermal conductivity of the composites is increased by 193% and the compressive strength is improved from 1.40 MPa to 1.94 MPa. This contribution provides a guidance for designing high-performance carbon-based electromagnetic shielding materials.