Multi-dimensional and Level-by-Level Assembly Strategy on Flexible and Sandwich-type Nanoheterostructures for High-performance Electromagnetic Interference Shielding
To shield massive electromagnetic pollutions and meet increasing demand in portable electronics, developing flexible, lightweight and high-performance electromagnetic interference (EMI) shielding materials with good environmental friendliness is urged but still challenging. Herein, a multi-dimensional and level-by-level assembly strategy is creatively proposed to construct free-standing and sandwich-type nanoheterostructures consisting of the flexible cotton-derived carbon fibers (CFs), magnetic and conductive nickel nanoparticles (Ni NPs) and high conductivity and large surface area of dandelion-like graphene (DLG), via a high-precision combination technology of magnetron sputtering‒plasma enhanced chemical vapor deposition. The multiple spatial-scale DLG/Ni NPs/CFs composites achieve a remarkable conductivity of 625 S m−1 and an outstanding EMI shielding effectiveness of ~50.6 dB in the X-band (8.2‒12.4 GHz) which can be classified as attenuation levels of “AAAA” for professional use. The dielectric loss from multiple polarizations is principally responsible for the electromagnetic loss of the composites. Besides, the large surface area of heterogeneous interfaces and defects in DLG contribute to enhancing the amount of polarization. In addition, the ultrathin and ultralight composites (d=0.65 mm, ρ=113 mg cm‒3) can be bended, twisted and folded, revealing the excellent processability for commercial uses. More importanly, this novel structual design concept opens up an interesting promissing research field of novel next-generation EMI shielding materials.