Synchronously Enhancing Mechanical Strength and Conductivity of MXene Nanofluidic Fibers with Multivalent Ion Crosslinking

Developing high-performance nanofluidic fibers with synergetic ionic and electric conductivities is promising for human–machine interface interaction. In such a scenario, inter- and intra-forces in constituent flakes are recognized as crucial factors in determining the derived nanofluidic fiber performance. In this work, the rheological properties of Ti₃C₂T_x MXene solution are systematically optimized by regulating the electrostatic interaction via introducing multivalent metal cations. As a result, such multivalent cations trigger ionic crosslinking and remarkably strengthen the interaction force between nanosheets, which even forms into a tight fiber-shaped gel network. A series of cations, such as K⁺, Na⁺, Mg²⁺, Zn²⁺, and Al³⁺, are introduced to enhance the ionic cross-linking between interconnected flakes. The thus-prepared Zn²⁺-Ti₃C₂T_x fiber exhibits a remarkable electrical conductivity of 11 200 S cm⁻¹, a tensile strength of 252 MPa, and an ionic conductivity of 2.51 × 10⁻³ S cm⁻¹. This multivalent cation crosslinking strategy could offer some insights into developing functional nanofluidic fibers for wearable or healthcare applications.