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

Abstract 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 (Ti 3 CNT 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.