One‐Pot Asymmetric Assembly of Hierarchical Triple‐Layer Nickel Foam/Titanium Carbonitride MXene Aerogels for Superior Microwave Absorption and Tailored Thermal Management

Rapid strides in portable electronics and telecommunication technologies have sharply escalated the demand for high-performance electromagnetic interference (EMI) shielding materials that effectively suppress secondary electromagnetic pollution while simultaneously integrating thermal management. Here an innovative, lightweight, hierarchical triple-layer aerogel structure comprising nickel (Ni) foam (NiF), titanium carbonitride (Ti₃CNT_x) MXene, and poly(vinyl alcohol) (PVA), fabricated via a facile, one-step bidirectional freeze-casting process is presented. This asymmetric aerogel architecture strategically employs an impedance-matching MXene/PVA top layer for optimized microwave entry, a NiF/MXene/PVA interlayer introducing magnetic loss and enhancing heat conduction, and a reflective, thermally foamed MXene bottom layer promoting internal reflection for superior energy absorption. With an ultralow density (240 mg cm^-3) and robust mechanical stability supported by hydrogen bonding, the aerogels enable synergistic energy loss mechanisms, delivering outstanding EMI shielding effectiveness (91.7 dB) and absorptivity (88%) at 3.4 mm thickness. Tailored thermal management is achieved through contrasting thermal conductivities across layers; the insulating top layer (0.056 W m^-1 K^-1) restricts vertical heat flow, whereas the conductive NiF-based interlayer (0.932 W m^-1 K^-1) accommodates efficient lateral heat dissipation upon microwave absorption. This multifunctional, scalable material platform sets a benchmark for addressing EMI shielding challenges, holding great promise for future electronics and communication systems.