Robust and Highly Conductive Graphene‐Based Foams for Efficient Thermal Insulation, Flame Retardancy and Electromagnetic Interference Shielding

ABSTRACT Large scale production of robust and highly conductive graphene‐based foams for multifunctional electromagnetic interference (EMI) shielding remains a significant challenge. The pore‐walls within foams are vulnerable to collapse during traditional freeze‐drying, and it is required to balance the porosity and toughness. Herein, a facile method is proposed to fabricate large‐size graphene‐based foams (Cu‐GC) by foaming, copper ion‐diffusion‐induced gelation, and atmospheric pressure drying. This approach offers an efficient, controllable, and scalable strategy to produce multifunctional foams with customizable shapes and synergistic properties. The tailored conductive skeleton and ordered arc‐shaped pore walls endow Cu‐GC foams with a low density of 56.4 mg/cm 3 , high structural strength of 8.7 MPa, and excellent electrical conductivity (212 S m −1 ). The Cu‐GC foam achieves an outstanding EMI shielding effectiveness of 82.1 dB at 2 mm, and a specific shielding effectiveness of 7776.8 dB cm −2 g −1 . The finite element simulations further reveal the excellent shielding effect on electromagnetic waves for the Cu‐GC foam. The high electrical conductivity and porosity endow Cu‐GC foams with efficient electrothermal conversion and thermal insulation property. Moreover, it also shows excellent flame retardancy to improve its safety. This study offers new insights into the straightforward preparation of foams for multifunctional applications in EMI shielding protection.