MXene Nanosheet/Polypyrrole Composite Felt with a Continuous Impedance-Gradient Structure for Electromagnetic Wave Absorption

A layer–layer composite impedance-gradient structure can achieve good impedance matching characteristics. However, its impedance step and poor bonding fastness between layers are not conducive to the maximization of electromagnetic wave absorption. Based on the concentration-diffusion mechanism of interfacial freezing of conductive polymers, combined with the high conductivity of MXene nanosheets, a fabric structure with a continuous impedance gradient along the thickness direction was creatively constructed. Its intrinsic impedance from the bottom to the top of the fabric increases gradually to a value close to the free-space impedance. The minimum reflection loss of the produced MP-IIGF-1 is −31.98 dB, and its effective absorption bandwidth can cover the entire X-band (4.2 GHz). This work not only realizes the composite of nanoabsorbing agents but also proposes a method for implementing a continuous impedance gradient, thus providing a design concept for a broadband absorbing fabric and its impedance adjustment.