Wrinkled Heterostructure CoFe 2 O 4 /Graphene Oxide/Silver Nanowires/Aramid Nanofiber Composites with Electromagnetic Shielding

The small space inside a composite film limits the construction of an excellent conductive network, and the preparation of a multifunctional nanofiber composite film with high electromagnetic interference shielding efficiency (EMI SE) is still challenging. In this work, a fully conductive network with a wrinkled heterostructure is successfully constructed. First, cobalt ferrite/graphene oxide (CoFeGO) is synthesized by using the solvothermal method to prepare the point-surface conductive media. Subsequently, silver nanowires (AgNWs) with high aspect ratios are introduced. Using aramid nanofibers (ANF) as the substrate, we used vacuum filtration to obtain a CoFeGO/Ag/ANF composite film with a wrinkled heterostructure. The composite film exhibits excellent EMI SE of 51.3 dB, and its EMI SSE/t reaches a staggering 30700.9 dB·cm2·g–1, which is attributed to the increased transition loss due to the prominent internal “point-line-plane” complementary conductive network. The multiform components and porous network structure formed by the ANF enhance the internal reflection and polarization losses of electromagnetic waves (EMW). Moreover, hydrogen bonds are formed between CoFeGO, AgNWs, and ANF, effectively increasing the interfacial force and leading to an increase in the tensile strength from 39.6 to 80.3 MPa. In addition, the film exhibits excellent hydrophobic, flame-retardant, infrared stealth, thermoelectric, and photothermal conversion properties.