Highly conductive Ti₃C₂T_x MXene-based electromagnetic interference (EMI) shielding materials have shown great application potential in facing the increasingly serious electromagnetic radiation threat but are limited by their single-loss mechanism. Here, to enrich the wave loss mechanism, magnetic Ti₃C₂T_x MXene and conductive carbon nanotubes (CNTs) have been assembled into a flexible “brick-mortar” layered NiCo/MX–CNT film to simultaneously obtain high conductivity and strong attenuation capacity. Interestingly, by combining the strong attenuation ability of the magnetic NiCo/MX and high conductivity of CNTs, as well as the dense stacking “brick-mortar” layered structure, 99.99999991% (90.7 dB of EMI shielding effectiveness, SE) of the electromagnetic waves can be reflected and absorbed by the NiCo/MX–CNT composite film with only 53 μm thickness, which is one of the best shielding effects achieved and is superior to that of pure CNT film (∼71 dB) and pure MXene film (∼61 dB), even if they have higher conductivity. Moreover, the composite film can realize EMI shielding property modulation from 46 to 105 dB by adjusting the film thickness from 9 to 116 μm. The dense stacking “brick-mortar” layered structure endows the composite film with excellent flexibility, foldability, and robust mechanical properties, which significantly improve the practical potential in complex application environments.

Considering the complex actual environments and fields, the effective integration of multiple functions into one material is greatly and urgently required but still faces enormous challenges. Herein, an aerogel-based electromagnetic wave (EMW) absorber with the functions of piezoresistive sensing, infrared stealth, thermal insulation, and Joule heating was developed. Biomass bacterial cellulose (BC) and GO work as the carbon resource and reinforcing filler, respectively, obtaining a resilient (80% compression strain) and lightweight (7.81 mg cm⁻³) BC-derived C/thermal reduced GO (rGO) aerogel with the unidirectional cellular structure via the unidirectional freeze-drying and pyrolysis techniques. Remarkably, the prepared aerogel displayed the typical rGO loading and compression strain-dependent EMW absorption performance, and a significant improvement in the EMW absorption capacity with a minimum reflection loss (RL_min) of −46.11 dB and maximum effective absorption bandwidth (EAB_max) of 9.12 GHz at the thickness of 2.70 mm was achieved for C/rGO-10 (10 wt% rGO loading) when a 70% compression strain was applied compared to that in the natural state. Moreover, the aerogel also presented other attractive features, including stable, durable, and fast responsive piezoresistive sensing performances, effective thermal infrared stealth, and thermal insulating properties, and exceptional adjustable Joule heating performance. This study paves the way for developing high-performance EMW absorption materials with multiple functions to meet various applications.