Magnetic and dispersible FeCoNi-graphene film produced without heat treatment for electromagnetic wave absorption

Magnetic metal and graphene hybrids possess the high dielectric properties of graphene and the high magnetic properties of the metal, which render them suitable as electromagnetic (EM) wave-absorbing materials. In this research, we fabricated an EM wave-absorbing film with excellent performance (reflection loss of -68 dB) based on a FeCoNi@graphene hybrid. We developed a new electroless plating method for fabricating magnetic metal@graphene hybrids without any heat treatment, and the new hybrid material showed a higher saturation magnetization (120.4 emu/g) than that of a hybrid material prepared by conventional electroless plating (56.8 emu/g). The sizes, structures, and oxidation ratios of the FeCoNi nanoparticles on graphene were different depending on the synthesis method, and Ni played an important role in the growth of the FeCoNi nanoparticles. The FeCoNi@graphene hybrid was well dispersed in tetrahydrofuran, and thus, could be fabricated into free-standing and flexible composite films by mixing with thermoplastic polyurethane. The high permeability of the FeCoNi@graphene film resulted in a high EM wave-absorbing performance due to impedance matching. These results provide an important advancement toward not only the commercialization of EM wave-absorbing films for healthcare, electronic reliability, and tactical security applications but also the development of magnetic metal and graphene hybrid materials using a scalable process.