Asymmetric magnetic-electric dual-functional composite foams for ultra-efficient electromagnetic interference shielding with unprecedented low reflection

Asymmetric composite foams comprised of iron oxide decorated reduced graphene oxide (Fe3O4@rGO)/earbon nanotube (CNT)/thermoplastic polyurethane (TPU) foams and a silver layer were developed by vacuum-assisted hot-pressing and supercritical carbon dioxide (scCO(2)) foaming. The magnetic-electric dual-functional network constructed by Fe3O4@rGO and CNT nanofillers rendered the foam excellent impedance matching and wave attenuation capability, achieving -46.8 dB reflection loss at similar to 2 mm sample thickness. With the reflective silver layer, the asymmetric composite foam realized a unique "low reflection-absorption-reflection-reabsorption" EM wave depletion mechanism and reached preeminent total shielding effectiveness (SET) of 89.2-103.5 dB with a reflection shielding effectiveness (SER) of 0.24-0.83 dB. The optimized composite foam achieved a low reflectivity (R) of 0.05 (Average value) and a minimum value of 0.001, which holds the lowest record among EMI shielding materials with comparable SE. This work provides new insights into the design of high-efficiency shielding materials with ultra-low reflection features for cutting-edge EMI shielding applications.