Alternating Multilayered Ti₃C₂T_x/Co Sandwich with Co Frosting for Superior Electromagnetic Wave Absorption...

MXene-based wave-absorbing materials face challenges in practical applications such as severe sheet stacking and low dielectric loss. Herein, we used two-dimensional (2D) layered Ti₃C₂T_x MXene as the backbone and stereoscopic magnetic cobalt (Co) crystals as the buttress and coating to design a connected three-dimensional layered sandwich heterostructure. By adjustment of the ratio of raw materials, Co crystals were anchored both within the interlayer gaps of the adjacent 2D sheets and on their surfaces through electrostatic and ion-dipole interactions with the functional groups of Ti₃C₂T_x. This prevented magnetic and sheet agglomeration and formed a uniform frosting-like coating on the surface. Owing to this unique structure and multicomponent design, the Ti₃C₂T_x/Co composites were enriched with nonhomogeneous interfacial structures and magnetic/dielectric synergy. They exhibited excellent impedance matching properties with multiple electromagnetic wave absorption (EWA) mechanisms. After optimization, the Co-modified Ti₃C₂T_x composite exhibited a minimum reflection loss (RL_min) of -49.57 dB at a thickness of 2.5 mm with an effective absorption bandwidth of 2.88 GHz, surpassing most previously reported MXene-based EWA materials. The simulated far-field radar-scattering cross-section (RCS) results further indicated that the Ti₃C₂T_x/Co composite consistently maintained an RCS value of <-15 dB m² across all test angles, highlighting its superior EWA capability. The Ti₃C₂T_x/Co composite exhibited a relatively low infrared emissivity and an excellent infrared stealth performance. This study provides a new route for fabricating MXene-based EWA composite materials with enhanced versatility and effectiveness.