Ultralight Ti3C2Tx/CNF aerogel with outstanding electromagnetic interference shielding efficiency

•Bacterial cellulose (BC) was used as a binder to compound with fewer layers of Ti3C2Tx. On the one hand, BC was used as the binder to construct the Ti3C2Tx/BC three-dimensional macrostructure, on the other hand, the intercalation of BC reduced the aggregation between the Ti3C2Tx nanosheets.•In the three-dimensional macroscopic body, BC is transformed into CNF after heat treatment, and becomes a conductive medium, forming a conductive channel between Ti3C2Tx laminae, which significantly reduces the contact resistance between Ti3C2Tx laminae. Ti3C2Tx nanosheets as the conductive main phase, the shielding mechanism is mainly the reflection.•In the heat treatment process, the conversion of BC to CNF can be regulated by controlling the temperature, and the conductivity can be controlled in this process.•Further by adjusting Ti3C2Tx content (low filler content) to achieve effective control of electromagnetic parameters, Ti3C2Tx/CNF aerogel under the premise of maintaining low density to obtain excellent comprehensive performance. MXene is widely used as electromagnetic interference (EMI) shielding material due to its excellent electrical conductivity. However, nanosheet structure leads to agglomeration, which has certain limitations on the application. Inspired by bacterial cellulose (BC) has good adhesion and can transform into carbon nanofibers (CNF) after heat treatment, we prepared Ti3C2Tx/CNF aerogels by bidirectional freeze-drying method and heat treatment. Under the bonding effect of BC, the highly conductive phase Ti3C2Tx nanosheets were connected into a periodic porous aerogels, which hindered the agglomeration of Ti3C2Tx nanosheets. BC is converted into CNF after heat treatment, forming a conductive network in aerogel. It significantly improves the EMI shielding performance to 44.5 dB at a thickness of 2 mm. The density of the obtained aerogel is only 24 mg•cm−3, and the specific EMI shielding efficiency (SSE, shielding value/density) value reaches 1844.6 dB cm3 g−1, which has a good comprehensive performance. The lightweight porous Ti3C2Tx /BC aerogel (ρ=24 mg•cm−3)was prepared by bidirectional freeze-drying method with two-dimensional MXene Ti3C2Tx nanosheets as the conductive phase and BC as the binder. Ti3C2Tx /CNF aerogel was prepared by heat treatment to adjust BC structure, and good shielding performance (44.5 dB, d = 2.0 mm) was obtained by adjusting electromagnetic parameters of the aerogel. The specific EMI shielding efficiency of Ti3C2Tx/CN