Reduced graphene oxide porous films containing SiC whiskers for constructing multilayer electromagnetic shields

Developing lightweight and flexible thin films for electromagnetic interference (EMI) shielding is of great importance. Porous thin films of reduced graphene oxide containing SiC whiskers (SiC@RGO) for EMI shielding were prepared by a two-step reduction of graphene oxide (GO), in which the two steps were chemical reduction by HI and the solid phase microwave irradiation. A significant increase of the film thickness from around 20 to 200 μm was achieved due to the formation of a porous structure by gases released during the 3 s of solid phase microwave irradiation. The total shielding effectiveness (SE_T) and the reflective SE (SE_R) of the SiC@RGO porous thin films depended on the GO/SiC mass ratio. The highest SE_T achieved was 35.6 dB while the SE_R was only 2.8 dB, when the GO/SiC mass ratio was 4∶1. The addition of SiC whiskers was critical for the multi-reflection, interfacial polarization and dielectric attenuation of EM waves. A multilayer film with a gradient change of SE values was constructed using SiC@RGO porous films and multi-walled carbon nanotubes buckypapers. The highest SE_T of the multilayer films reached 75.1 dB with a SE_R of 2.7 dB for a film thickness of about 1.5 mm. These porous SiC@RGO thin films should find use in multilayer or sandwich structures for EMI absorption in packaging or lining.