h-CoFe₂O₄/Ti₃C₂T_x/BNC Hybrid Aerogels with Modulation Impedance Matching for Electromagnetic Wave Absorption and Health Monitoring

Given the limitations of single-function electromagnetic wave-absorbing materials (EWAMs) in meeting the evolving demands of complex usage scenarios, there is a growing need for structure–function integrated composites that offer a combination of microwave absorption, human monitoring, and thermal insulation. This study successfully synthesized two-dimensional (2D) Ti 3 C 2 T x MXene via selective etching of Al from the Ti 3 AlC 2 MAX phase. By introducing MXene into a composite of hydroxylated CoFe 2 O 4 nanoparticles ( h -CFO NPs) and bacterial nanocellulose (BNC) to modulate the electromagnetic performance of the EWAMs. The optimized electromagnetic parameters and three-dimensional (3D) porous structure achieve enhanced impedance matching of the wave absorber. The h -CFO/BNC/MXene ( h -CFO@CM 73 ) hybrid aerogel demonstrates superior electromagnetic wave absorption (EMWA) performance due to the synergistic effects of conductive loss, magnetic loss, interfacial polarization, and dipole polarization, where a minimum reflection loss (RL min ) of −32.66 dB at a thickness of 4.5 mm, an effective absorption bandwidth (EAB) of 10.70 GHz within the test range, and an EMWA efficiency reaching up to 99.92% were realized. Moreover, the hybrid aerogel presents sensitive sensing capabilities, detecting human joint movements, breathing, and vocalizations. Additionally, the developed hybrid aerogels exhibit commendable thermal insulation and infrared camouflage properties. Consequently, the fabricated multifunctional hybrid aerogel has excellent potential for monitoring care of infants, children, and pregnant women.