Shear delamination of multilayer MXenes

Abstract

MXenes, a class of two-dimensional (2D) materials, are synthesized by etching MAX phase precursors to produce multilayer MXenes, where individual 2D sheets are held together by van der Waals forces. Typically, single 2D flakes of MXene are produced by chemical intercalation to delaminate multilayer MXenes, which is a time-intensive process that produces excess waste. In addition, intercalants affect the properties of MXenes. Many of them are toxic, limiting medical applications. Moreover, the process does not work for certain MXene chemistries, such as halogen-terminated MXenes produced by molten salt etching. This work demonstrates an alternative approach, shearing multilayer MXenes with a three-roll mill to produce single- and few-layer Ti3C2Tx flakes without chemical intercalants. The high shear produced Ti3C2Tx flakes showed a capacitance of 337 F g(-1), comparable to flakes made with LiCl intercalation, in 3 M H2SO4. We generalize this approach by shear delamination of other MXenes.