Versatile cellulose nanofibril assisted preparation of ultralight, scalable carbon nanotube aerogel-based electromagnetic wave absorbers with ultrahigh reflection loss

The sustainable cellulose nanofibril (CNF) was efficiently utilized to facilitate the preparation of a type of ultralight, high-porosity carbon nanotube (CNT) hybrid aerogel-based electromagnetic wave (EMW) absorbers. CNF not only serves as a green surfactant to avoid the agglomeration of CNT, but also acts as supporting matrix or binder to promote the construction of porous CNT-based aerogels. Furthermore, the CNF precursor contributes to the generation of CNF-derived nanocarbon (CNFC) for a high-efficiency dielectric modulator, leading to the tuneable electromagnetic parameters and good impedance matching. Combined with the loss capacity of CNFC, the EMW absorption performance of CNT-based aerogels is enhanced. Consequently, the hybrid aerogels show EMW absorption performance involving an effective absorption bandwidth of 3.3 GHz and an ultrahigh reflection loss of −76.46 dB at a filling ratio of 5 wt%, outperforming that of other CNT-based EMW absorbers ever reported. The synergistic effects of multiple EMW absorption mechanisms for the hybrid aerogels were analyzed at length, demonstrating the indispensable roles of the CNF or CNFC in constructing high-efficiency CNT-based EMW absorbers. Combined with the green, sustainable, facile, and scalable preparation approach, the carbon aerogel-based EMW absorbers are highly promising for applications in electromagnetic compatibility or protection and aerospace.