Low-temperature carbonized biomimetic cellulose nanofiber/MXene composite membrane with excellent microwave absorption performance and tunable absorption bands

2D transition metal carbides and nitrides (MXenes) have gained much interest in microwave absorption. However, the high conductivity of MXenes results in inferior absorption performance. To solve this problem, Cellulose nanofiber (CNF) is compounded with MXenes to build membranes with biomimetic structures. CNF not only contributes to adjusting the electromagentic parameters, but also enhances the microwave attenuation and regulates the absorption band. In this work, nacre-like and loofah-like carbonized CNF/MXenes membranes were successfully prepared. The self-assembly of CNF and MXene avoids the impedance mismatch, and the biomimetic structures enhance conductive loss, polarization loss and multiple reflection. The results show that nacre-like carbonized CNF/MXene membrane (CCM) exhibits absorbing performance with the minimum reflection loss (RL_min) of −42.2 dB and the Effective absorption band (EAB) of 7.12 GHz. Meanwhile, the absorption peaks are mainly concentrated on X-band. Further, as the morphology changes to porous layers, the RL_min of loofah-like CCM increases to −63.8 dB, whose EAB is 7.32 GHz at 2.5 mm, and the main absorption peaks shift to Ku-band. Besides, the possible absorption mechanism of biomimetic composite membranes has been expounded. This work provides a versatile strategy for CNF/MXene composite membrane with biomimetic structures on excellent and tunable microwave absorption performance.