Polydopamine decoration on 3D graphene foam and its electromagnetic interference shielding properties.

3D graphene foam was recently demonstrated to exhibit excellent electromagnetic interference (EMI) shielding performance. In this work, we prepared 3D graphene foams by incorporating a surface modification process of graphene via self-polymerization of dopamine with a subsequent foaming process. The multiple roles played by polydopamine (PDA), including as nitrogen doping source and as an enhancement tool to achieve higher extent of reduction of the graphene through providing wider pathways and larger accessible surface areas were discussed in detail. Despite the presence of the PDA which acted as barriers among the graphene layers that hindered the electrons movement, the enhanced reduction of graphene sheets and the polarization effects introduced by PDA decoration compensated the negative effect of the barrier on EMI shielding effectiveness (SE). As a result, the PDA decorated 3D graphene foams showed improved EMI shielding effectiveness (SE) compared to PDA-free graphene foam (from 23.1 to 26.5dB). More significantly, the EMI shielding performance of the PDA decorated graphene foam was much superior to all existing carbon-based porous materials when the thickness of the specimen was considered.