Ascorbic acid-induced fiber-scrolling of titanium carbide Ti₃C₂T MXene

Changing the morphology of two-dimensional materials often offers an efficient and effective means to exploit their electronic and mechanical properties. Two-dimensional materials such as graphene can be scrolled into one-dimensional fibers via simple sonication. Unfortunately, scrolling MXene nanosheets into fibers is quite challenging, especially Ti₃C₂T composed of three layers of titanium atoms and two layers of carbon atoms. Herein, we report a new method to fabricate MXene fibers via ascorbic acid (AA) induced scrolling of Ti₃C₂T nanosheets. An unusual AA-Ti₃C₂T interaction is discovered in that intercalated AA molecules bind to and interact with the Ti₃C₂T surface in the form of a hydrogen bonding-bonded assembly instead of as individual molecules, and a sheet-scrolling mechanism is proposed based on this interaction. The as-obtained MXene fibers exhibit a compact cross-section, and the diameter can be tailored from hundreds of nanometers to several micrometers through tuning the MXene/AA ratio. Moreover, the storage modulus of the MXene-fiber sponge attains its maximum value of ∼1 MPa when a unique morphology comprising both fibers and not-yet-scrolled sheets is presented. This work offers a new strategy of fiber-shaping MXenes for applications in structural composites and flexible electronics.