Architecture Design of a Bamboo Cellulose/Nb₂CT_x MXene/ZIF-67-Derived Lightweight Co/Nb₂CT_x/Carbon Aerogel for Highly Efficient Electromagnetic Wave Absorption, Thermal Insulation, and Flame Retardant

Designing biomass-derived carbon-based lightweight electromagnetic wave (EMW) absorbers with multiple functions is promising research. However, the design of carbon-based EMW absorbers with multifunctionality for practical application remains a substantial challenge. Herein, a porous architecture engineering strategy was used to prepare a high-performance EMW absorption composite material with thermal insulation and flame-retardant properties The multifunctional Co/Nb₂CT_x/carbon aerogel with porous architecture composed of a bamboo-derived carbon aerogel, two-dimensional (2D) Nb₂CT_x, and ZIF-67-derived Co nanoparticles was prepared. Bamboo cellulose and few-layered Nb₂CT_x MXene constructed the three-dimensional (3D) aerogel architecture, ZIF-67 was then uniformly anchored on the aerogel skeleton through chemical deposition, and the Co/Nb₂CT_x/carbon aerogel was finally prepared by pyrolysis. The 3D interconnected network heterostructure not only contributes to conduction loss but also prolongs multiple reflection and scattering paths of EMW, which can improve the dielectric loss. Nb₂CT_x and Co nanoparticles play an important part in modulating the impedance matching and promoting the EMW attenuation ability due to the plenty of dipole/interfacial polarization loss and supplementary magnetic loss. The obtained Co/Nb₂CT_x/carbon aerogel possesses low density (54.03 mg cm^–3) and achieves excellent reflection loss and broad effective absorption bandwidth (−60.25 dB and 4 GHz, respectively) at an ultrathin thickness of 1.67 mm with an ultralow filling content of 10 wt %. The radar cross section (RCS) reduction value can reach 31.24 dB m^–2, indicating that the absorber can effectively reduce the probability of the target being detected by the radar detector. The strategy of porous architecture engineering provides guidance for the design of biomass-based electromagnetic wave absorption materials with thermal insulation property and flame-retardant capacity.