"Cardiac-like functionalization" porous magnetic MXene/carbon dots films via constructing bidirectional electromagnetic wave attenuation paths for high-performance microwave absorption

To meet the demand for miniaturisation in electronic devices, the development of absorptive films with adjustable thickness and uniform structure enables direct integration into microelectronic components, thereby addressing electromagnetic interference issues within constrained volumes. To address the limitation of single electromagnetic wave transmission pathways in few-layer MXene films. Three-dimensional interconnect films were fabricated using in situ NH₃ etching technology. The self-stacking phenomenon of MXene was suppressed by pre-deposited carbon dots (CDs), thereby exposing more active sites and enhancing the horizontal attenuation path for electromagnetic waves. During the annealing process, the decomposition of certain CDs releases NH₃ gas, which in situ etches MXene nanosheets. This forms large in-plane pores within the film, thereby constructing vertical electromagnetic wave transmission channels. Moreover, Fe₃O₄ nanospheres optimise impedance matching whilst incorporating a magnetic loss mechanism. Ultimately, the MXene/CDs/Fe₃O₄ (MCFs) film not only achieves a minimum reflection loss (RL_mᵢ_n) value of −51.05 dB at 13.2 GHz but also attains a maximum effective absorption bandwidth (EAB_max) value of 4.96 GHz, significantly outperforming pure MXene films. CST simulations indicate that at 13.2 GHz, the radar cross section (RCS) of the PEC plate covered with MCFs decreases by 24.91 dB m² under perpendicular incidence across an incidence angle range of −60° to +60°. This study offers novel insights into developing high-performance MXene-based absorber films by constructing bidirectional electromagnetic wave transmission pathways.