Ultrathin carbon foams for effective electromagnetic interference shielding

Ultrathin carbon foams with the thickness about 24 μm were fabricated by the pyrolysis of polyimide/graphene composite foams. The addition of graphene was verified to stabilize the porous structure of the foams and accelerate their graphitization process simultaneously. Consequently, the well-defined carbon foams exhibited much higher electromagnetic interference (EMI) shielding effectiveness (SE) up to 24 dB over the frequency range of 8-12 GHz, in comparison with the non-foamed counterparts. The possible mechanism behind the phenomenon was attributed to their enhanced microwave absorption via the internal multiple scattering and reflections. Moreover, the SE could be further improved to 43 and 51 dB by increasing the sample thickness gradually to 51 and 73 μm, respectively. The carbon foams with high thermal stability are very promising in the fabrication of ultrathin EMI shields for thermally harsh applications.