Ultrathin and flexible biomass-derived C@CoFe nanocomposite films for efficient electromagnetic interference shielding

Developing ultrathin, lightweight, flexible and efficient electromagnetic interference (EMI) shielding materials is still a long-standing issue. Herein, a series of biomass derived carbon composite films with superior EMI shielding performance are reported. The cotton derived carbon fabric wrapped with CoFe alloy nanoparticles (CCF@CoFe) was prepared by pyrolysis at temperature of 600–800 °C and subsequently encapsulated by polyimide (PI) resin to obtain the CCF@CoFe/PI films. The prepared composite films present favorable flexibility, remarkable tensile strength of ~10 MPa and exceptional EMI shielding efficiency of ~32 dB over the X-band with the thickness of 0.16 mm. In addition, the EMI shielding performance of the composite films can be adjusted by changing the CoFe loading content and pyrolysis temperature, and an EMI shielding efficiency of ~62 dB is achieved by stacking 6 layers of nanocomposite films, shielding 99.999937% of incident electromagnetic waves with thickness of only 0.98 mm. In view of excellent comprehensive properties, this ultrathin and low-cost biomass derived films are highly promising materials for EMI shielding in practical applications.