Ti₃C₂T_x MXene-Based Hybrid Aerogels with Tunable Porosity

Three-dimensional (3D) porous structures based on MXene nanosheets have recently emerged as high-performance materials for electronic and biomedical applications. However, the high colloidal stability of single-layered MXene nanosheets in water complicates their assembly into a multiscale structure. In this work, we demonstrate that the controlled diffusion of a positively charged polyelectrolyte (PE) into the single-layer MXene suspension allows for a range of free-standing 3D structures with tunable porosity. The MXene/PE assemblies are developed by the complexation of PE chains and MXene nanosheets at the interface and the subsequent diffusion of PE chains into the bulk of MXene suspension. The shape and orientation of the pores made between MXene nanosheets are engineered by the colloidal behavior of the MXene suspension and the MXene/PE molecular interactions. Such interactions, in turn, are controlled by tuning the ionization degrees of the components and the polyelectrolyte chain length. Also, we show that the same molecular approach can be applied to design MXene-based hollow fibers. The final 3D porous hybrids are electroconductive (10 to 20 S/cm) and provide a basis for the rational design of MXene-based macro assemblies as promising candidates for electromagnetic interference shielding, tissue engineering, and environmental remediation applications.