Two-dimensional transition-metal carbides/carbonitrides (MXenes) with both superb electrical conductivity and hydrophilicity are promising for fabricating multifunctional nanomaterials and nanocomposites. However, the construction of three-dimensional (3D) and lightweight MXene macroscopic assemblies with excellent electrical conductivity and mechanical performances has not been realized due to the weak gelation capability of MXene sheets. Herein, we demonstrate an efficient approach for constructing highly conductive 3D Ti3C2T x porous architectures by graphene oxide assisted hydrothermal assembly followed by directional freezing and freeze-drying. The resultant hybrid aerogels exhibit aligned cellular microstructure, in which the graphene sheets serve as the inner skeleton, while the compactly attached Ti3C2T x sheets present as shells of the cell walls. The porous and highly conductive architecture (up to 1085 S m-1) is highly efficient in endowing epoxy nanocomposite with a high electrical conductivity of 695.9 S m-1 and an outstanding electromagnetic interference (EMI)-shielding effectiveness of more than 50 dB in the X-band at a low Ti3C2T x content of 0.74 vol %, which are the best results for polymer nanocomposites with similar loadings of MXene so far. The successful assembly methodology of 3D and porous architectures of Ti3C2T x would greatly widen the practical applications of MXenes in the fields of EMI shielding, supercapacitors, and sensors.
Keywords: Ti3C2Tx MXene aerogel; electrical conductivity; electromagnetic-interference shielding; polymer nanocomposites; reduced graphene oxide.