Recent advance in the construction of 3D porous structure Ti3C2Tx MXene and their multi-functional applications

MXene, a new two-dimensional nanomaterial, has attracted much attention due to its hydrophilicity, excellent electrical conductivity, stability, electrochemical property, etc. We have given a brief introduction to the preparation of MXene nanosheets, as well as the 1D and 2D MXene-based materials with their applications. However, the spontaneous aggregation and re-stacking of nanosheets in 1D and 2D MXene due to hydrogen bonding and van der Waals forces are not beneficial to the industrialization applications, and therefore, the construction of 3D porous structures is an effective way to solve this issue. However, the small transverse dimensions and weak mechanical properties of MXene itself do not allow for the spontaneous formation of strong, stable, and self-supportable 3D porous structure. Therefore, combining MXene with other materials, such as carbon-based materials, metal oxides, spinel, polymers, metal-based nanoparticles, have been considered as the most effective method for the preparation of 3D MXene-based porous structure. Thus, in this review, we have illustrated the current construction techniques of 3D porous Ti3C2Tx MXene including template method, selfassembly method and 3D printing method, etc. The wide applications of 3D MXene in supercapacitors, electromagnetic shielding, seawater desalination, piezoresistive sensors and catalysis via microstructures structures regulation, are also summarized in this work. Finally, the prospects regarding the 3D MXene-based composites with strong mechanical property, pore structures regulation, cost-effective synthesis route and the new applications fields are proposed. This work will help to develop a more exquisite design of 3D MXene-based materials for their future commercial applications.