Dual-gradient MXene/AgNWs/Hollow-Fe3O4/CNF composite films for thermal management and electromagnetic shielding applications

With the increasing prevalence of electronic devices, there is a pressing need for composite films that offer both efficient thermal management and superior electromagnetic interference (EMI) shielding. To address this, we developed a novel composite film featuring a controllable conductive-magnetic dual-gradient structure, composed of cellulose nanofibers (CNF), MXene, silver nanowires (AgNWs), and hollow ferric oxide (Fe₃O₄). This film was fabricated using a straightforward, cost-effective layer-by-layer vacuum filtration method. Leveraging CNF as the matrix material endows the film with remarkable flexibility. The integration of 2D MXene, 1D AgNWs, and 0D hollow Fe₃O₄ significantly enhances the film's thermal conductivity through multidimensional particle interactions, achieving a maximum value of 2.92 W/mK. Additionally, the dual-gradient structure of the film-comprising a transition layer and a reflection layer-improves EMI shielding efficiency by balancing high EMI shielding effectiveness with low electromagnetic wave reflection. Specifically, for the dual-gradient configuration (MAF)-25-CNF, the absorption coefficient (A) of electromagnetic waves incident on the low conductivity side reaches 0.23, and the shielding effectiveness reaches 45.8 dB. These findings highlight the potential of MXene/AgNWs/Fe₃O₄/CNF composite films with a controllable conductive-magnetic dual-gradient structure for applications in electronics, electrical engineering, and wearable technologies.