Structural design of asymmetric gradient alternating multilayered CNF/MXene/FeCo@rGO composite film for efficient and enhanced absorbing electromagnetic interference shielding

Abstract

With the strong support of the government for emerging technology industries, electromagnetic waves have brought convenience to people's lives, but also become an undeniable new source of pollution. Therefore, it is vital to develop new high-performance electromagnetic shielding materials. Herein, we designed a well-structured asymmetrical gradient multilayer composite film by constructing a controllable electromagnetic gradient. Using cellulose nanofibers as the matrix, a layer-by-layer filtration method was used to rationally distribute FeCo@rGO and MXene fillers to build an ordered multilayer structure that provides alternating conductive and magnetic gradients. Owing to gradient absorption shielding and reflection mechanisms for electromagnetic waves within the film layer, the EMI shielding efficiency (EMI SE) of the asymmetrical gradient alternating six-layer composite film reached 45.2 dB (X-band), and the reflection coefficient was reduced to 0.71 when 20 wt% filler was added. In addition, this composite film has good thermal conductivity and mechanical properties, exhibiting thermal conductivity of 2.90 W (m⁻¹ K⁻¹) and tensile strength of 26.2 MPa. This strategy provides a feasible approach for designing electromagnetic shielding composite materials with adjustable electromagnetic properties and has significant practical significance in expanding the application of MXene-based composite materials.