Water-Dispersible Ti3C2Tz MXene Nanosheets By Acid Free, Molten Salt Etching

Current methods to produce 2D Ti3C2Tz (MXene) nanosheets require hazardous HF for etching of the Ti3AlC2 MAX phase. Here, a molten salt (SnF2) etching method that produces water-dispersible Ti3C2Tz nanosheets without the need for HF is introduced. In molten salt etching, SnF2 may diffuse in between the layers during etching to form AlF3 and Sn as byproducts. Sn spheres form internally in the layers to push the layers apart and form large d-spacings. The stable, aqueous Ti3C2Tz nanosheet dispersion yields a ζ potential of -31.7 mV, owing to -OH terminal groups introduced from a KOH wash. X-ray diffraction and electron microscopy confirm the formation of Ti3C2Tz etched clay with substantial d-spacing as compared to the clay from a traditional HF-process. This work is the first to use molten salt etching to successfully prepare colloidally stable aqueous dispersions of Ti3C2Tz nanosheets. The Ti3C2Tz nanosheet film and clay produced by this method also show excellent conductivity, specific and areal capacitance