MXene-Silver Nanowire/Cellulose Nanofiber Composite Films for High-Performance Electromagnetic Interference Shielding, Thermal Management, and Efficient Energy Harvesting

Integrating multifunctional characteristics into one flexible electromagnetic interference (EMI) shielding material is highly desirable for improving its working performance and holding a broad range of modern applications. To simultaneously promote EMI shielding efficiency with integrated thermal management and triboelectric energy harvesting, we fabricated a cellulose nanofiber-MXene/silver nanowire (CMA) composite film with a double-layered structure by a simple two-step vacuum-assisted filtration process followed by vacuum drying. Contributed by the highly efficient double-layered structure and the unique synergism generated by the combination of two different nanofillers, the obtained double-layered CMA composite (dCMA) film exhibits a satisfying EMI shielding effectiveness (EMI SE) of 67 dB, a high specific EMI shielding effectiveness (SSE/t) of 7019 dBcm 2 g –1, and in-plane thermal conductivity of 12.3 W/m·K, while maintaining excellent electrical conductivity of 2515 S/cm along with desirable mechanical strength and thermal durability. Compared with homogeneously mixed composite films, the dCMA composite film delivers excellent electrical conductivity, EMI shielding efficiency, and thermal management performance. More importantly, the dCMA-based triboelectric nanogenerator (TENG) can generate a maximum open-circuit voltage of ∼30.5 V/cm 2 and a short-circuit current of ∼0.93 μA/cm 2 with a maximum power of ∼42.9 μW/cm 2 that can successfully power up portable electronics such as a sports stopwatch and an electronic calculator by harvesting energy from simple hand-tapping motions. Collectively, our developed dCMA composite films hold promising potential for a wide range of applications in multifunctional self-powered EMI shielding and thermal management materials, which can accelerate their commercial viability.